Rhs Element Repeat-encoded Proteins


The Rhs Family of major Rhs element repeat-encoded genes contains five named genes, rhsA-E, and four ygenes, yibS, yibJ, ylbH and ybfO. rhsE and the ygenes are apparent pseudogenes, mostly C-terminal fragments. RhsA has a role in in polysaccharide synthesis/export, but no functions have been attributed to RhsB-D. It has been suggested that all Rhs systems are involved in intercellular growth inhibition, suggesting that the Rhs proteins are secreted from E. coli and that the variable C-terminal domains are toxic to neighboring cells when secreted to the outside of the cell (Koskiniemi, 2013). Whether or not the Rhs proteins of E. coli are secreted is is not clear since they apparently do not start with signal peptides.

The Rhs genes are part of a larger Rhs element repeat region. The Rhs regions includes addition ORFs of unknown function, including many apparent pseudogenes. Because the Rhs element repeats are nearly identical, they are major hotspots for chromsomal duplications formed by homologous recombination, along with the seven rrn operons.

The Rhs family of Gram- bacterial long conserved proteins is distantly related to the WapA family of Gram+ bacteria (Foster, 1993).

The C-terminal tails of secreted proteins D. dadantii RhsA and RhsB and B. subtilis WapA are toxic and mediate intercellular competition in a manner similar to contact-dependent inhibition (CDI) (Koskiniemi, 2013).

The Rhs proteins are one of many delivery systems for polymorphic toxin systems implicated in intercellular intra-specific conflicts; the Rhs proteins may facilitate inter-cellular contact inhibition with filamentous structures formed by RHS/YD proteins (Zhang, 2012).


EcoFam Multiple Alignment of the Rhs E. coli K-12 Paralog Family including 5 pseudogenes:
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EcoFam Paralog Tree of the Rhs E. coli K-12 Paralog Family including 5 pseudogenes:
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EcoFam Multiple Alignment of the Full Length RhsA-D Family:
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EcoFam Paralog Tree of the Full Length RhsA-D Family:
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The multiple alignments and figures were created using the EBI Muscle server. The unrooted tree diagrams were drawn using the Phylodendron server at Indiana University.