Team:Imperial College London/M2/genes

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===YgiV===
 
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<b>Background:</b>
 
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In nature, the colanic acid synthesis phase occurs prior to biofilm formation. The latter process of biofilm formation is associated with the upregulation of a number of virulence factors. The transcription factor YgiV blocks the progression into biofilm formation by maintaining colanic acid production. Thus YgiV serves to increase acid resistance and decrease virulence.
 
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{{Imperial/09/Division}}
 
===Rfal===
===Rfal===

Revision as of 14:55, 10 October 2009

Through the course of evolution, E.coli have equipped themselves with a multitude of defences to enable colonisation of the intestine. We are using two global transcription factors (RcsB & YgiV) to hijack this natural process in a way that maximises acid resitance. We have additionally upregulated a third enzyme (rfal) to enhance the encapsulation of single cells (over and above colony encapsulation). Finally, the two biosynthetic genes (OtsA & OtsB) code for enzymes responsible for the production of trehalose. Our manipulation of endogenous pathways reduces virulence while enchancing pill functionality.


Contents

RcsB

Background:

RcsB is a transcription factor that forms part of a phosphorelay system. In response to membrane stress, RcsB is phosphorylated into its DNA binding form. In this state, it is able to regulate ~5% of the E.coli genome 4.


The Rcs Phosphorelay System:

In this system, RcsC encodes a membrane bound sensor kinase, while RcsB functions as the response regulator. The protein RcsA is an auxiliary activator protein that heterodimerises with RcsB to induce a mucoid phenotype. Levels of RcsA are controlled by the ATP dependent protease Lon.


RcsB upregulates the following genes:


Colanic Acid Biosynthesis:

wcaF
  • Putative colanic acid biosynthesis acetyltransferase 2
gmd

Codes for GDP-mannose 4,6-dehydratase which is a subunit of GDP-mannose 4,6-dehydratase. This enzyme is involved in colanic acid biosynthesis.

wcaD
  • Predicted colanic acid polymerase
wza
  • This codes for a lipoprotein that is required for colanic acid translocation through the outer membrane. The lipoprotein is a subunit of the capsular polysaccharide export apparatus.
fcl
  • Codes for a subunit of GDP-fucose synthase. This enzyme is involved in colanic acid biosynthesis.




General Protective:

ivy (Inhibitor of Vertebrate lysozyme)
  • Discovered in 2001 as the first bacterial lysozyme inhibitor. This Type-C lysozyme inhibitor resides in the periplasm.1
MilC (Membrane-bound lysozyme inhibitor of Type C lysozyme)
  • This is a lipoprotein that resides in the membrane. 1



OsmC (Osmotically-inducible protein C)
  • This protein provides defense against oxidative stress caused by exposure to organic hydroperoxides. 2 3


KatE
  • Codes for a subunit of heme d synthase / hydroperoxidase. This bacterial catalase protects against osmotic stress.




Global Regulators:

Sra (stationary-phase-induced ribosome-associated)

Sra is a sub-stoichiometric component of the 30S ribosomal subunit that is more abundant at stationary phase than during log phase growth.

rprA

rprA is a gene encoding a small RNA molecule that is involved in the post-transcriptional control of the alternative sigma factor, ("sigma S").


FtsA

FtsA is an essential cell division protein which colocalizes with FtsZ to the septal ring structure.

FtsZ
  • Essential cell division protein.
yfbR
  • dCMP phosphohydrolase


Membrane Proteins:

bdm (biofilm-dependent modulation protein)
OsmB
  • OsmB encodes an outer membrane lipoprotein.
OsmY

Hyperosmotically inducible periplasmic protein

PhnQ
ycfJ
  • Uncharacterized putative inner membrane protein.
ygaC
spy
ymgD
  • Putative periplasmic protein.
ypeC
  • Unknown function


ymgG
YbaY

Predicted outer membrane lipoprotein




References

1) [http://www.ncbi.nlm.nih.gov/pubmed/19136591 The Rcs two-component system regulates expression of lysozyme inhibitors and is induced by exposure to lysozyme]

2) [http://www.ncbi.nlm.nih.gov/pubmed/19346340 Gene Expression Induced in Escherichia coli O157:H7 upon Exposure to Model Apple Juice]

3) [http://www.ncbi.nlm.nih.gov/pubmed/14627744 Structural and functional features of the Escherichia coli hydroperoxide resistance protein OsmC.]

4) [http://www.ncbi.nlm.nih.gov/pubmed/16153174?ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum The Rcs phosphorelay: a complex signal transduction system.]





Rfal

Background:

In the majority of E.coli, the enzyme Rfal joins the O-antigen to the membrane-bound lipid core molecule. Since the K-12 strain has an insertion mutation in the gene coding for O-antigen, the enzyme Rfal is free to join colanic acid to the lipid core.

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