Difference between revisions of "Part:BBa K200000"

Revision as of 09:56, 20 October 2009

Colanic acid global regulator -> RcsB

Regulation for Capsular Synthesis (RCS) Phosphorelay System

RcsB is a transcription factor that forms part of a phosphorelay system. As the name suggests, a phosphorelay system consists of a series of nodes down which a phosphate group is passed. The transfer of this phosphate group down along the Rcs relay system is initiated by membrane stress. Once the phosphate group has been passed to RcsB, it can bind to DNA and act as a transcription factor.

The Rcs phosphorelay is composed of two membrane-anchored proteins, RcsC and RcsD, and a cytoplasmic protein, RcsB. In response to a signal, the sensor kinase RcsC autophosphorylates and the phosphoryl group is transferred to RcsB, via RcsD. RcsB can both homodimerise and heterodimerise with RcsA, these two complexes serve to regulate different operons.

RcsB as a transcription factor

Together, the RcsB~P homodimer and the RcsB~P+RcsA heterodimer are thought to regulate ~5% of the E.coli genome 4. RcsB~P acts as a positive regulator of a number of genes including capsule genes responsible for colanic acid production. 2 This is via the activation of the ugd/cps operon which is required for capsule synthesis.
Colanic acid is a heteropolymer containing glucose, galactose, fucose, and glucuronic acid.

It is important to note that RcsB is a global regulator found in many [http://en.wikipedia.org/wiki/Enterobacteria Enterobacteria]. In Salmonella, up to 38 genes were found to be up-regulated by RcsB including ftsZ which affects the rate of cell division. 1 The majority of upregulated genes are associated with enhancing structural integrety and acid resistance. 22 genes were found to be downregualted by RcsB in the same microarray experiment.3

RcsB and the positive feedback loop

RcsB~P is able to heterodimerise with the protein RcsA. The RcsB~P+RcsA complex acts as a transcription factor that induces the expression of a number of genes. One of these genes codes for RcsA, this initiates a positive feedback loop.

Usage and Biology

Colanic acid is an exopolysaccharide secreted by some bacterial species to protect themselves from the environment that surrounds them.

The gene was used alongside YgiV and Rfal by the Imperial iGEM 2009 [http://2009.igem.org/Team:Imperial_College_London The E.ncapsulator] team to upregulate colanic acid production as part of the auto-encapsulation mechanism.

Sequence and Features

Assembly Compatibility:

10
COMPATIBLE WITH RFC[10]
12
COMPATIBLE WITH RFC[12]
21
COMPATIBLE WITH RFC[21]
23
COMPATIBLE WITH RFC[23]
25
COMPATIBLE WITH RFC[25]
1000
COMPATIBLE WITH RFC[1000]

References

1 pmid=1597415
2 pmid=2404948
3 pmid=19124574

</biblio>

@@ Line 14: / Line 14: @@
 It is important to note that RcsB is a global regulator found in many [http://en.wikipedia.org/wiki/Enterobacteria Enterobacteria]. In Salmonella, up to 38 genes were found to be up-regulated by RcsB including ftsZ which affects the rate of cell division. <cite>1</cite> The majority of upregulated genes are associated with enhancing structural integrety and acid resistance. 22 genes were found to be downregualted by RcsB in the same microarray experiment.<cite>3</cite>
+===RcsB and the positive feedback loop===
+RcsB~P is able to heterodimerise with the protein RcsA. The RcsB~P+RcsA complex acts as a transcription factor that induces the expression of a number of genes. One of these genes codes for RcsA, this initiates a positive feedback loop.
+<html>
+<p class="ecoparagraph">
+<map name="MAP91791">
+<area coords="147,18,177,35" onmouseover="return overlib('H-NS transcriptional dual regulator represses transcription from associated promoter<br>The exact location of this binding site is unknown or not specified.<br><b>Evidence:</b> Gene expression analysis<br>The nature of binding of this protein is not well known.');" onmouseout="return nd();">
+<area coords="0,74,32,91" onmouseover="return overlib('RcsAB transcriptional dual regulator activates transcription from associated promoter<br><b>Distance to transcription start site:</b> -166.5 (ranging from -173 to -160)<br><b>Evidence:</b> Gene expression analysis [Ebel99], Automated inference based on similarity to consensus sequences [Ebel99]');" onmouseout="return nd();">
+<area coords="34,74,66,91" onmouseover="return overlib('RcsAB transcriptional dual regulator activates transcription from associated promoter<br><b>Distance to transcription start site:</b> -125.5 (ranging from -132 to -119)<br><b>Evidence:</b> Binding of cellular extracts, Site mutation [Wehland00], Binding of purified proteins [Wehland00]');" onmouseout="return nd();">
+<area coords="147,0,184,17" onmouseover="return overlib('GadE transcriptional activator activates transcription from associated promoter<br>The exact location of this binding site is unknown or not specified.<br><b>Evidence:</b> Binding of purified proteins [Hommais04], Gene expression analysis [Hommais04]');" onmouseout="return nd();">
+<area coords="104,60,165,91" onmouseover="return overlib(' <b>Gene:</b>  rcsA    EG10820    b1951    ECK1949<br><b>Synonyms:</b> cpsR<br><b>Location:</b> 2,021,992 -> 2,022,615   <br> <b>Product:</b> positive DNA-binding transcriptional regulator of capsular polysaccharide synthesis, activates its own expression, subunit of RcsAB transcriptional dual regulator');" onmouseout="return nd();">
+<area coords="24,0,184,108" onmouseover="return overlib('<b>Operon:</b> rcsAp (Experim. ev.)  <BR><b>Tr.Activators:</b> (GadE RcsAB) <BR><b>Tr.Inhibitors:</b> (Hns)');" onmouseout="return nd();">
+<area coords="0,0,184,108"  onmouseover="return overlib('<b>Operon</b>: rcsA');" onmouseout="return nd();">
+</map>
+<img src="https://static.igem.org/mediawiki/2009/8/89/Op8.gif" usemap="#MAP91791" border="0">
+ </p>
+</html>
 ===Usage and Biology===