Part:BBa_K200003
Rfal
Rfal (Waal ligase) is an enzyme responsible for the ligation of an O-antigen to the core oligosaccharide in the Gram-negative bacterium's outer membrane.
Unlike other exopolysaccharides, colanic acid does not naturally bind to the cell surface but rather forms a thick mesh between cells. While Waal Ligase usually links the O-antigen to the core oligosaccharide, in K-12 it links colanic acid to the core oligosaccharide. This is because E.coli K-12 does not produce O-antigen due to an insertion mutation.
Usage and Biology
LipoPolySaccharyde is a major component of the outer cell wall in Gram-negative bacteria. It is constituted of three main components: the O-antigen, the core polysaccharides and the lipid A (see Fig. 1).
The O-antigen is a highly variable chain of polysaccharydes and is physically linked to the core.
The core component is made up of a short chain of sugars (oligosaccharide) and is linked to both the O-antigen and the Lipid A components of the cell wall.
The Lipid A component of the LPS contains fatty acid chains which causes the LPS to dock into the outer membrane of the Gram-negative bacterium.
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.
The gene was used alongside RcsB and YgiV as part of the Imperial iGEM 2009 [http://2009.igem.org/Team:Imperial_College_London The E.ncapsulator] project to bind the colanic acid capsule to the cellular membrane.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 754
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
Requirements
- Gram-negative bacterium
- Colanic acid producing gene (rcsB)
References
<biblio>
- function pmid=15838026
- Function2 pmid=19019161
- Function3 pmid=15215252
</biblio>
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