Team:Newcastle/Swarming

From 2010.igem.org

Revision as of 22:41, 21 October 2010 by Alankoh (Talk | contribs)

iGEM Homepage Newcastle University BacillaFilla Homepage Image Map

Contents

Swarming

Newcastle swarming.jpg

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. 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.

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.

swrA

In the undomesticated strain 3610, the gene swrA along with the gene swrB 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. The laboratory strain 168 contains a fameshift mutation in the gene swrA and thus the stain moves on the surface with a very slow pace.

swrC

It provides resistance to the antimicrobial action of the peptide surfactin.

efp

efp stands for "Elongation Factor P" and this gene helps in the non-dendritic swarming.

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.
Newcastle University logo.png    Newcastle cbcb logo.pngNewcastle Biomedicine logo.gif    Team Newcastle CEG logo.gif
Newcastle iww logo.jpg  UNIPV Pavia Logo.gif  Newcastle BBSRC.gif    Newcastle Genevision logo.png Newcastle WelcomeTrust.jpg
FaceBook Icon