Team:Newcastle/Swarming

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==Swarming==
==Swarming==
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[[Image:Newcastle_swarming.jpg|centre|400px]]
 
Our project requires ''Bacillus subtilis'' 168 to swarm along the cracks to the site of repair. However  
Our project requires ''Bacillus subtilis'' 168 to swarm along the cracks to the site of repair. However  
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it is known that the domesticated ''Bacillus subtilis'' 168 is not unable to swarm on a solid surface eg. agar plate, while the undomesticated ''Bacillus subtilis'' 3610 exhibit swarming properties. The swarming properties requires two factors, the flagella, which serves as a propeller to push the bacteria forward. And the production of surfactin, which is a natural surfactant which helps in reducing surface tension. In ''B. subtilis'' 168, both genes that are involved in the process, ''swrA'' and ''sfp'' have undergone frameshift mutation, therefore they are defective. As such, our team have decided to repair the genes by designing a biobrick that contain both genes.  
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it is known that the domesticated ''Bacillus subtilis'' 168 is not unable to swarm on a solid surface eg. agar plate, while the undomesticated ''Bacillus subtilis'' 3610 exhibit swarming properties (Figure 1). The swarming properties requires two factors, the flagella, which serves as a propeller to push the bacteria forward. And the production of surfactin, which is a natural surfactant which helps in reducing surface tension. In ''B. subtilis'' 168, both genes that are involved in the process, ''swrA'' and ''sfp'' have undergone frameshift mutation, therefore they are defective. As such, our team have decided to repair the genes by designing a biobrick that contain both genes.  
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[[Image:Newcastle_swarming.jpg|centre|300px]]
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'''Figure 1:''' Agar plates are inoculated with either ''B. subtilis'' 3610 (left) or ''B. subtilis'' 168 (right) and incubated overnight at 37°C.
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===Swarming biobrick===
===Swarming biobrick===

Revision as of 22:47, 21 October 2010

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Contents

Swarming

Our project requires Bacillus subtilis 168 to swarm along the cracks to the site of repair. However it is known that the domesticated Bacillus subtilis 168 is not unable to swarm on a solid surface eg. agar plate, while the undomesticated Bacillus subtilis 3610 exhibit swarming properties (Figure 1). The swarming properties requires two factors, the flagella, which serves as a propeller to push the bacteria forward. And the production of surfactin, which is a natural surfactant which helps in reducing surface tension. In B. subtilis 168, both genes that are involved in the process, swrA and sfp have undergone frameshift mutation, therefore they are defective. As such, our team have decided to repair the genes by designing a biobrick that contain both genes.

Newcastle swarming.jpg

Figure 1: Agar plates are inoculated with either B. subtilis 3610 (left) or B. subtilis 168 (right) and incubated overnight at 37°C.


Swarming biobrick

Newcastle Swarming biobrick.png

The swarming biobrick consists of the sfp and swrA gene under a constitutive promoter, Pveg. The expression of sfp would allow the post translational modification of the immature surfactin peptide encoded by the srfABCD operon. The mature surfactin is then transported out of the cell, to reduce surface tension. The swrA gene helps in the biosynthesis of flagellum. swrA acts on the the gene sigD, which in turn acts as a transcription for the genes required in the late flagellum biosynthesis.

Pathway

Swarming of the colony cells starts when the concentration of the signalling peptide ComX and the pentapeptide pheromone CSF (encoded by phrC) reach a critical concentration and activates the sensor kinase ComP by phosphorylating it. ComP is a part of two component transduction system and thus activates response regulator ComA which is present downstream to ComP.

ComA targets srf operon which consists of four genes viz srf A,B,C, and D and it also targets ComS which is present upstream to the srf operon and it activates competence by displacing MecA from ComK and thus MecA is targeted for proteolysis by ClpC/ClpB. ComK regulates the genes required for competence.

While ComA is activating srf operon, another gene named sfp encodes 4' phosphopantetheinyl transferase which is required to activate each of the four surfactin synthases by the post translational modification of Srf A, Srf B, Srf C, and Srf D, which are required for the non ribosomal assembly of the surfactin heptapeptide.

Simultaneously, gene swrA activates the transcription factor sigD (sigma D) which acts on the genes required in the late flagellum biosynthesis.

Bibliography

  1. Julkowska, D, Obuchowski, M, Holland, IB & Se, SJ 2005, "Comparative Analysis of the Development of Swarming Communities of Bacillus subtilis 168 and a Natural Wild Type : Critical Effects of Surfactin and the Composition of the Medium." Society, vol. 187, no. 1, pp. 65-76.
  2. Kearns, DB & Losick, R 2004, "Swarming motility in undomesticated Bacillus subtilis." Molecular Microbiology, vol. 49, no. 3, pp. 581-590.
  3. Kearns, DB, Chu, F, Rudner, R & Losick, R 2004, "Genes governing swarming in Bacillus subtilis and evidence for a phase variation mechanism controlling surface motility." Molecular microbiology, vol. 52, no. 2, pp. 357-69.
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