Team:SDU-Denmark/project-t

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====Photosensor====
====Photosensor====
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In our system we want to be able to control the amount of flow in the channel, through a remote signal. The signal we have chosen is light since we want to avoid altering the chemical composition of the fluid running through the channel. Having looked at previous iGEM work on light sensitive systems which have all been focused on transcriptional regulation[(http://partsregistry.org/wiki/index.php/Part:BBa_I15010 e.g. I15010)], we realized that we would need a different approach for the fast response times our system requires. We have therefore focused our work on proteorhodopsins that integrate into the chemotaxis pathway, giving us very fast responses to light stimulation. <br><br>
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In our system we want to be able to control the amount of flow in the channel, through a remote signal. The signal we have chosen is light since we want to avoid altering the chemical composition of the fluid running through the channel. Having looked at previous iGEM work on light sensitive systems which have all been focused on transcriptional regulation ([http://partsregistry.org/wiki/index.php/Part:BBa_I15010 e.g. I15010]), we realized that we would need a different approach for the fast response times our system requires. We have therefore focused our work on proteorhodopsins that integrate into the chemotaxis pathway, giving us very fast responses to light stimulation. <br><br>
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Our construct centers around a synthetic protein created by Spudich ''et al.''[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 9]]. It is a fusion chimeric protein that consists of an archaeal proteorhodopsin SopII (Sensory Rhodopsin II) and its transducer protein HtrII, both from ''Natronomonas pharaonis''. These are coupled to a Tar domain from a transmembrane receptor from ''Salmonella enterica''. The Tar domain is the part of the receptor that couples with CheA and CheW, and although it is taken from a different species, it has been shown to work in ''E. coli'' as well [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 10]]. In the construct we are working with light should act as an attractant, reducing the tumbling rate upon illumination (see picture). This might help us to control our pumping power, by decreasing the fraction of bacteria tumbling in the channel by increasing light stimulus, thus promoting linear drive. The photosensor should be most active in light with a wavelength of about 500nm, according to the original article. We have used DNA sent to us from the original authors to isolate the coding sequence for the protein generator.<br><br>
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Our construct centers around a synthetic protein created by Spudich ''et al.'' [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 9]]. It is a fusion chimeric protein that consists of an archaeal proteorhodopsin SopII (Sensory Rhodopsin II) and its transducer protein HtrII, both from ''Natronomonas pharaonis''. These are coupled to a Tar domain from a transmembrane receptor from ''Salmonella enterica''. The Tar domain is the part of the receptor that couples with CheA and CheW, and although it is taken from a different species, it has been shown to work in ''E. coli'' as well [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 10]]. In the construct we are working with light acting as an attractant, reducing the tumbling rate upon illumination (see picture). This might help us to control our pumping power, by decreasing the fraction of bacteria tumbling in the channel by increasing light stimulus, thus promoting linear drive. The photosensor should be most active in light with a wavelength of about 500nm, according to the original article. We have used DNA sent to us from the original authors to isolate the coding sequence for the protein generator.<br><br>
Note that although the bacteria will be stationary in our system, since they are glued to the inner surface of the flowchannel, our construct in reality confers a phototactic ability to ''E. coli''.
Note that although the bacteria will be stationary in our system, since they are glued to the inner surface of the flowchannel, our construct in reality confers a phototactic ability to ''E. coli''.
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== Retinal Generator ==
== Retinal Generator ==
====Retinal requirements of light-sensing proteins====
====Retinal requirements of light-sensing proteins====
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Proteorhodopsins belong to a group of molecules consisting of a protein called an opsin with a cromophore(usually a retinal enantiomer) attached as a prosthetic group. The retinal chromophore is the molecule responsible for the initial light-activation, as it undergoes photoizomerization after being struck by a photon. It is this change in conformation of the retinal molecule that is relayed through the entire rhodopsin-transducer complex to activate/deactivate the CheW/A complex in the cytosol. Thus either an external supply of retinal or an internal supply, generated by means of genes coding for enzymes in the retinal biosynthesis pathway are required, if we wish to see phototactic behaviour in our cells.<br><br>
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Proteorhodopsins belong to a larger group of proteins called retinylidene proteins consisting of proteins called an opsins with a retinoid cromophore such as retinal attached as a prosthetic group[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 11]]. In our system retinal is responsible for the initial light-activation, as it undergoes photoizomerization when it is struck by a photon[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 12]]. It is this change in conformation of the retinal molecule that is relayed through the entire protein complex to regulate chemotaxis [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 12]]. Thus either an external supply of retinal or an internal supply, generated by means of genes coding for enzymes in the retinal biosynthesis pathway are required, if we wish to see phototactic behaviour in our cells [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 10]].<br><br>
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These light-sensitive pigments can be found in a large variety of organisms from archaea and bacteria to both uni- and multicellular eukaryotes. Many plants and microbes have complete retinal biosynthesis pathways in their genomes, to help drive their rhodopsins. In these organisms rhodopsins play an essential role, not only for photosensing but also directly in energy production. In fact in some organisms rhodopsins are used to create proton motive force directly by pumping protons out into the extracellular space using light energy to drive the process. Humans and other animals on the other hand often only have enzymes coding for the final steps of the pathway, more on which later. They rely on a supply of retinal precursors or vitamin A (a group of molecules consisting of retinal and it's metabolites) in their diet. This is why vitamin A deficiency causes night-blindness as an early symptom in humans.<br><br>
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Light-sensitive pigments can be found in a large variety of organisms from archaea and bacteria to both uni- and multicellular eukaryotes [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 11]], [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 13]], [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 14]]. Many plants and microbes have complete retinal biosynthesis pathways in their genomes [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 15]]. In these organisms rhodopsins play an essential role, not only for photosensing but also directly in energy production [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 11]],[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 13]],[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 14]]. In fact in some organisms rhodopsins are used to create proton motive force directly by pumping protons out into the extracellular space using light energy to drive the process [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 14]]. Humans and other animals on the other hand often only have enzymes coding for the final steps of the pathway, more on which later. They rely on a supply of retinal precursors or vitamin A (a group of molecules consisting of retinal and it's metabolites) in their diet [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 16]]. This is why vitamin A deficiency causes night-blindness as an early symptom in humans [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 17]].
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<br><br>
==== Retinal biosynthesis ====
==== Retinal biosynthesis ====
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Retinal is also synthesized from the enzymatic cleavage of some carotenes. In our system we focus on cleavage of beta-carotene, partly because it yields 2 all-trans retinal molecules which are the molecules we desire, and partly because the beta-carotene biosynthesis pathway has already been introduced to ''E. coli'' by the [http://partsregistry.org/Part:BBa_K274210 Cambridge 2009 ] iGEM team.
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Retinal can be synthesized from the enzymatic cleavage of some carotenes. In our system we focus on cleavage of beta-carotene, partly because it yields 2 ''all-trans'' retinal molecules which are the molecules we desire, and partly because the beta-carotene biosynthesis pathway has already been introduced to ''E. coli'' by the [http://partsregistry.org/Part:BBa_K274210 Cambridge 2009 ] iGEM team.
The Cambridge construct uses genes from the plant pathogen ''Pantoea ananatis'' and our construct completes the pathway to retinal with a gene from the common fruit fly, ''Drosophila melanogaster''.  <br>
The Cambridge construct uses genes from the plant pathogen ''Pantoea ananatis'' and our construct completes the pathway to retinal with a gene from the common fruit fly, ''Drosophila melanogaster''.  <br>
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The Cambridge 2009 construct consists of four genes ''crtE'', ''crtB'', ''crtI'' and ''crtY'' from ''P. ananatis'' that together make up the pathway that converts farnesyl pyrophosphate to beta-carotene, which is a precursor for retinal. farnesyl pyrophosphate is naturally pressent in ''E. coli''. <br>
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The Cambridge 2009 construct consists of four genes ''crtE'', ''crtB'', ''crtI'' and ''crtY'' from ''P. ananatis'' that together make up the pathway that converts farnesyl pyrophosphate to beta-carotene, which is a precursor for retinal. Farnesyl pyrophosphate is naturally present in ''E. coli''. <br>
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• ''crtE'' encodes the protein geranyl-geranyl pyrophosphate synthase that converts farnesyl pyrophosphate to geranyl-geranyl pyrophosphate by elongating it by one unit of isopentenyl. <br>
• ''crtE'' encodes the protein geranyl-geranyl pyrophosphate synthase that converts farnesyl pyrophosphate to geranyl-geranyl pyrophosphate by elongating it by one unit of isopentenyl. <br>
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The pathway (including the step that generates retinal) is summed up below: <br><br>
The pathway (including the step that generates retinal) is summed up below: <br><br>
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[[image:https://static.igem.org/mediawiki/2010/c/cb/Team-SDU-Denmark-Retinal_generator.png |500px|thumb|Figure 3: The retinal Biosynthesis pathway.]]
 
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To introduce the final step from beta-carotene to retinal, we use the gene ''ninaB'' from ''D. melanogaster''. This gene encodes the protein beta-carotene 15,15’-monooxygenase, which cleaves beta-carotene to produce two molecules of trans-retinal under the consumption of oxygen. <br>
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[[Image:Team-SDU-Denmark-Retinal_generator.png |400px|thumb|Figure 3: The retinal Biosynthesis pathway.]]
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We have inserted the part K343006 into a different plasmid from the K274210 part since both parts are very long, so a plasmid containing both wouldn't have been viable.
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To introduce the final step from beta-carotene to retinal, we use the gene ninaB from D. melanogaster. This gene encodes the protein beta-carotene 15,15’-monooxygenase, which cleaves beta-carotene to produce two molecules of trans-retinal under the consumption of oxygen [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 18]]. We have inserted the part K343006 into a different plasmid from the K274210 part since both parts are very long, so a plasmid containing both wouldn't have been viable for transformations.
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=== Further use of the retinal BioBrick ===
=== Further use of the retinal BioBrick ===
==== Role in light-based signal transduction ====
==== Role in light-based signal transduction ====
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Since retinal plays such an essential role in photosensing in both eukaryotes as well as bacteria and archaea, all work with rhodopsins and proteorhodopsins will need a retinal supply to function. This supply might come from the external environment, but it is an appealing thought that we might be able to supply the retinal from an internal source. Our project centers around phototaxis, but other constructs combining photorhodopsins with other membrane associated tyrosine kinases may also be imagined, opening vast posibilities for regulation of phopsphorylation cascades using light as input. In such systems, retinal biosynthesis could play a very valuable role.<br>
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Since retinal plays such an essential role in photosensing in both eukaryotes as well as bacteria and archaea, all work with rhodopsins and proteorhodopsins will need a retinal supply to function. This supply might come from the external environment, but it is an appealing thought that we might be able to supply the retinal internally. Our project centers around phototaxis, but constructs combining photorhodopsins with other membrane associated tyrosine kinases may also be imagined, opening vast posibilities for regulation of phopsphorylation cascades using light as input. In such systems, retinal biosynthesis could play a very valuable role.<br>
== Hyperflagellation ==
== Hyperflagellation ==
=== Background ===  
=== Background ===  
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Motility can be a very beneficial quality for a microorganism. Evolution has therefore provided bacteria with two general means of transportation; the flagella and the pili. These qualities allow the bacteria to move away from a hostile environment and towards more favorable conditions. Flagella and pili are however viewed as a virulence factor as they also serve as an advantage in colonizing a host organism and yet they can cause a strong immune response [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 11]]. <br><br>
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Motility can be a very beneficial quality for a microorganism. Evolution has therefore provided bacteria with two general means of transportation; the flagella and the pili. These qualities allow the bacteria to move away from a hostile environment and towards more favorable conditions. Flagella and pili are however viewed as a virulence factor as they also serve as an advantage in colonizing a host organism and yet they can cause a strong immune response [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 19]]. <br><br>
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Many organisms are able to synthesize a flagellum, if the external environment calls for it. The synthesis of a flagellum is a huge and energy consuming process and is therefore tightly regulated by the bacteria’s external environment. One of the most well characterized flagellation systems is the one found in ''E. coli''. Here at least 50 genes are involved in the hierarchical synthesis and operation of the flagella. These genes are sorted into 15 operons which are expressed in a transcriptional cascade separated into three classes. Class I consists of the master operon ''flhDC''. The active FlhDC protein is a hexamer organized into an FlhD<sub>4</sub>C<sub>2</sub> complex with a computed value of 96,4kDa [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 12]]. The homodimeric FlhC protein is able to bind DNA, while the FlhD homodimers are not. The formation of the FlhDC complex however, stabilizes and increases the DNA binding ability [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 13]]. The transcription of ''flhDC'' is heavily regulated by nutritional and environmental conditions. Flagellum synthesis is inhibited at high temperatures, at high salt concentrations, at extreme pH or in the presence of carbohydrates, low molecular alcohols or DNA gyrase inhibitors, as these conditions stimulate growth as opposed to motility [https://2010.igem.org/Team:SDU-Denmark/project-t#References 14]. Because the flagellum synthesis is so energy consuming, the process is not started unless the environment calls for motility rather than growth. In fact, in situations where nutrition is plenty over a long period, the bacteria will focus on growth and over time lose the ability to synthesize the flagellum, as seen with the ''E. coli'' strain MG1655 localized in mouse intestines [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 15]].
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Many organisms are able to synthesize a flagellum, if the external environment calls for it. The synthesis of a flagellum is a huge and energy consuming process and is therefore tightly regulated by the bacteria’s external environment. One of the most well characterized flagellation systems is the one found in ''E. coli''. Here at least 50 genes are involved in the hierarchical synthesis and operation of the flagella. These genes are sorted into 15 operons which are expressed in a transcriptional cascade separated into three classes. Class I consists of the master operon ''flhDC''. The active FlhDC protein is a hexamer organized into an FlhD<sub>4</sub>C<sub>2</sub> complex with a computed value of 96,4kDa [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 20]]. The homodimeric FlhC protein is able to bind DNA, while the FlhD homodimers are not. The formation of the FlhDC complex however, stabilizes and increases the DNA binding ability [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 21]]. The transcription of ''flhDC'' is heavily regulated by nutritional and environmental conditions. Flagellum synthesis is inhibited at high temperatures, at high salt concentrations, at extreme pH or in the presence of carbohydrates, low molecular alcohols or DNA gyrase inhibitors, as these conditions stimulate growth as opposed to motility [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 22]]. Because the flagellum synthesis is so energy consuming, the process is not started unless the environment calls for motility rather than growth. In fact, in situations where nutrition is plenty over a long period, the bacteria will focus on growth and over time lose the ability to synthesize the flagellum, as seen with the ''E. coli'' strain MG1655 localized in mouse intestines [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 23]].
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[[Image:Team-SDU-Denmark-flagella-overview-1.png|600px|'''Figure 4: Overview of the flagellum synthesis cascade.''']]
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[[Image:Team-SDU-Denmark-flagella-overview-1.png|600px|thumb|center|Figure 4: Overviews cascade of the flagellum synthesis.]]
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[[Image:Team SDU-Denmark FlhD4C2 structure.JPG|thumb|right|210px|'''Figure 5:'''3D structure of the FlhD<sub>4</sub>C<sub>2</sub> hexamer.[[https://2010.igem.org/Team:SDU-Denmark/project-t#References 23]][[https://2010.igem.org/Team:SDU-Denmark/project-t#References 24]]]] <br>
The FlhD<sub>4</sub>C<sub>2</sub> hexamer acts as a transcription factor for the Class II genes, which encodes the basal body, that is embedded in the cell membrane as well as hook proteins, which are transported to the cell exterior through the basal body. Another Class II gene is the σ<sup>28</sup> transcription factor, which is responsible for the transcription of the Class III genes. This includes ''fliC'', which encodes the flagellin subunit that composes the flagella “tail”. To ensure that the Class III genes are not transcribed before the assembly of the basal body and the hook is complete another Class II protein FliM acts as an anti-sigma factor and bind σ<sup>28</sup>, thereby preventing the transcription of ''fliC''.<br><br>
The FlhD<sub>4</sub>C<sub>2</sub> hexamer acts as a transcription factor for the Class II genes, which encodes the basal body, that is embedded in the cell membrane as well as hook proteins, which are transported to the cell exterior through the basal body. Another Class II gene is the σ<sup>28</sup> transcription factor, which is responsible for the transcription of the Class III genes. This includes ''fliC'', which encodes the flagellin subunit that composes the flagella “tail”. To ensure that the Class III genes are not transcribed before the assembly of the basal body and the hook is complete another Class II protein FliM acts as an anti-sigma factor and bind σ<sup>28</sup>, thereby preventing the transcription of ''fliC''.<br><br>
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Several studies regarding the motility of ''E. coli'' has shown the expression of the ''flhDC'' operon to be crucial [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 15]][[https://2010.igem.org/Team:SDU-Denmark/project-t#References 16]]. These focused on insertion sequence (IS) elements upstream of the ''flhDC'' regulon. IS are sequences that can be inserted randomly within the DNA and therefore serve as an important factor in the plasticity of the ''E. coli'' genome as well as in many other organisms. Generally the do not encode any genes apart from those responsible for their movement within the genome, however, they can also serve as activators of neighboring genes, by disrupting repression or by the formation of hybrid promoters (Baker). In the beforementioned studies, bacteria containing an activating IS upstrem of the ''flhDC'' operon showed an increased motility compared to bacteria without this IS. It is therefore resonable to asume that by placing a constitutive active promoter in front of the ''flhDC'' operon, hyperflagellation will be induced.
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Several studies regarding the motility of ''E. coli'' has shown the expression of the ''flhDC'' operon to be crucial [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 23]][[https://2010.igem.org/Team:SDU-Denmark/project-t#References 25]]. These focused on insertion sequence (IS) elements upstream of the ''flhDC'' regulon. IS are sequences that can be inserted randomly within the DNA and therefore serve as an important factor in the plasticity of the ''E. coli'' genome as well as in many other organisms. Generally they do not encode any genes apart from those responsible for their movement within the genome, however, they can also serve as activators of neighboring genes, by disrupting repression or by the formation of hybrid promoters [[https://2010.igem.org/Team:SDU-Denmark/project-t#References 25]]. In the beforementioned studies, bacteria containing an activating IS upstrem of the ''flhDC'' operon showed an increased motility compared to bacteria without this IS. It is therefore resonable to asume that by placing a constitutive active promoter in front of the ''flhDC'' operon, hyperflagellation will be induced.
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=References=
=References=
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[1] Li T-D, Gao J, Szoszkiewicz R, Landman U, Riedo E, [http://prb.aps.org/abstract/PRB/v75/i11/e115415 Structured and viscous water in subnanometer gaps],Phys. Rev. B 75, 115415 (2007)<br>
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# Li T-D, Gao J, Szoszkiewicz R, Landman U, Riedo E, [http://prb.aps.org/abstract/PRB/v75/i11/e115415 Structured and viscous water in subnanometer gaps],Phys. Rev. B 75, 115415 (2007)<br>
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[2] Samatey FA, et. al.,[http://www.nature.com/nature/journal/v410/n6826/abs/410331a0.html  Structure of the bacterial flagellar protofilament and implications for a switch for supercoiling]Nature 410, 331-337 (15 March 2001)<br>
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# Samatey FA, et. al.,[http://www.nature.com/nature/journal/v410/n6826/abs/410331a0.html  Structure of the bacterial flagellar protofilament and implications for a switch for supercoiling]Nature 410, 331-337 (15 March 2001)<br>
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[3] Macnab RM, [http://www.annualreviews.org/doi/full/10.1146/annurev.micro.57.030502.090832?select23=Choose How bacteria assemble flagella] Annual Review of Microbiology Vol. 57: 77-100 (October 2003)<br>
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# Macnab RM, [http://www.annualreviews.org/doi/full/10.1146/annurev.micro.57.030502.090832?select23=Choose How bacteria assemble flagella] Annual Review of Microbiology Vol. 57: 77-100 (October 2003)<br>
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[4] Berg HC, [http://www.annualreviews.org/eprint/cDJrS190m62mDRwHrlp9/full/10.1146/annurev.biochem.72.121801.161737 The rotary motor of bacterial flagella] Annual Review of Biochemistry Vol. 72: 19-54 (July 2003)<br>
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# Berg HC, [http://www.annualreviews.org/eprint/cDJrS190m62mDRwHrlp9/full/10.1146/annurev.biochem.72.121801.161737 The rotary motor of bacterial flagella] Annual Review of Biochemistry Vol. 72: 19-54 (July 2003)<br>
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[5] Berg HC, [http://www.ncbi.nlm.nih.gov/pubmed/1098551 Chemotaxis in bacteria] Annu Rev Biophys Bioeng. 1975;4(00):119-36.<br>
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# Berg HC, [http://www.ncbi.nlm.nih.gov/pubmed/1098551 Chemotaxis in bacteria] Annu Rev Biophys Bioeng. 1975;4(00):119-36.<br>
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[6] Zhao J, Parkinson JS, [http://jb.asm.org/cgi/content/abstract/188/9/3299 Mutational Analysis of the Chemoreceptor-Coupling Domain of the Escherichia coli Chemotaxis Signaling Kinase CheA ], Journal of Bacteriology, May 2006, p. 3299-3307, Vol. 188, No. 9<br>
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# Zhao J, Parkinson JS, [http://jb.asm.org/cgi/content/abstract/188/9/3299 Mutational Analysis of the Chemoreceptor-Coupling Domain of the Escherichia coli Chemotaxis Signaling Kinase CheA ], Journal of Bacteriology, May 2006, p. 3299-3307, Vol. 188, No. 9<br>
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[7] Sarkar MK, Paul K, Blair D,[http://www.pnas.org/content/early/2010/04/26/1000935107.short Chemotaxis signaling protein CheY binds to the rotor protein FliN to control the direction of flagellar rotation in ''Escherichia coli''], Published online before print May 3, 2010, doi: 10.1073/pnas.1000935107<br>
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# Sarkar MK, Paul K, Blair D,[http://www.pnas.org/content/early/2010/04/26/1000935107.short Chemotaxis signaling protein CheY binds to the rotor protein FliN to control the direction of flagellar rotation in ''Escherichia coli''], Published online before print May 3, 2010, doi: 10.1073/pnas.1000935107<br>
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[8] Hess JF, Oosawa K, Kaplan N, Simon MI, [http://www.ncbi.nlm.nih.gov/pubmed/3280143 Phosphorylation of three proteins in the signaling pathway of bacterial chemotaxis.], Cell. 1988 Apr 8;53(1):79-87.<br>
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# Hess JF, Oosawa K, Kaplan N, Simon MI, [http://www.ncbi.nlm.nih.gov/pubmed/3280143 Phosphorylation of three proteins in the signaling pathway of bacterial chemotaxis.], Cell. 1988 Apr 8;53(1):79-87.<br>
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[9] Trivedi VD, Spudich JL, [http://www.ncbi.nlm.nih.gov/pubmed/14636056 Photostimulation of a sensory rhodopsin II/HtrII/Tsr fusion chimera activates CheA-autophosphorylation and CheY-phosphotransfer in vitro.], Biochemistry. 2003 Dec 2;42(47):13887-92.<br>
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# Trivedi VD, Spudich JL, [http://www.ncbi.nlm.nih.gov/pubmed/14636056 Photostimulation of a sensory rhodopsin II/HtrII/Tsr fusion chimera activates CheA-autophosphorylation and CheY-phosphotransfer in vitro.], Biochemistry. 2003 Dec 2;42(47):13887-92.<br>
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[10] Jung K-H, Spudich EN, Trivedi VD, Spudich JL, [http://jb.asm.org/cgi/content/short/183/21/6365 An Archaeal Photosignal-Transducing Module Mediates Phototaxis in Escherichia coli], Journal of Bacteriology, November 2001, p. 6365-6371, Vol. 183, No. 21<br>
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# Jung K-H, Spudich EN, Trivedi VD, Spudich JL, [http://jb.asm.org/cgi/content/short/183/21/6365 An Archaeal Photosignal-Transducing Module Mediates Phototaxis in Escherichia coli], Journal of Bacteriology, November 2001, p. 6365-6371, Vol. 183, No. 21<br>
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[11] Josenhans, C. and Suerbaum, S. (2002) [http://www.ncbi.nlm.nih.gov/pubmed/12008914 The role of motility as a virulence factor in bacteria.] Int. J. Med. Microbiol. 291, 605-614 <br>
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# Spudich JL, Yang CS, Jung KH, Spudich EN [http://www.ncbi.nlm.nih.gov/pubmed/11031241 Retinylidene proteins: structures and functions from archaea to humans.], Annu Rev Cell Dev Biol. 2000;16:365-92.<br>
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[12] Wang, S. ''et al.'' (2006) [http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WK7-4HMGKJ0-D-H&_cdi=6899&_user=644074&_pii=S0022283605014063&_origin=search&_coverDate=01%2F27%2F2006&_sk=996449995&view=c&wchp=dGLzVzz-zSkzS&md5=6454221c64ea21917221df6a2bcfaaaa&ie=/sdarticle.pdf Structure of the Escherichia coli FlhDC Complex, a Prokaryotic Heteromeric Regulator of Transcription.] Journ. of mol. Biol. 355, 4, 798-808 <br>
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# Hoff WD, Jung KH, Spudich JL. [http://www.ncbi.nlm.nih.gov/pubmed/9241419?dopt=Abstract Molecular mechanism of photosignaling by archaeal sensory rhodopsins.], Annu Rev Biophys Biomol Struct. 1997;26:223-58<br>
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Latest revision as of 00:00, 28 October 2010