Rhs proteins from diverse bacteria mediate intercellular competition.

Proceedings of the National Academy of Sciences of the United States of America (2013-04-11)
Sanna Koskiniemi, James G Lamoureux, Kiel C Nikolakakis, Claire t'Kint de Roodenbeke, Michael D Kaplan, David A Low, Christopher S Hayes
RESUMEN

Rearrangement hotspot (Rhs) and related YD-peptide repeat proteins are widely distributed in bacteria and eukaryotes, but their functions are poorly understood. Here, we show that Gram-negative Rhs proteins and the distantly related wall-associated protein A (WapA) from Gram-positive bacteria mediate intercellular competition. Rhs and WapA carry polymorphic C-terminal toxin domains (Rhs-CT/WapA-CT), which are deployed to inhibit the growth of neighboring cells. These systems also encode sequence-diverse immunity proteins (RhsI/WapI) that specifically neutralize cognate toxins to protect rhs(+)/wapA(+) cells from autoinhibition. RhsA and RhsB from Dickeya dadantii 3937 carry nuclease domains that degrade target cell DNA. D. dadantii 3937 rhs genes do not encode secretion signal sequences but are linked to hemolysin-coregulated protein and valine-glycine repeat protein G genes from type VI secretion systems. Valine-glycine repeat protein G is required for inhibitor cell function, suggesting that Rhs may be exported from D. dadantii 3937 through a type VI secretion mechanism. In contrast, WapA proteins from Bacillus subtilis strains appear to be exported through the general secretory pathway and deliver a variety of tRNase toxins into neighboring target cells. These findings demonstrate that YD-repeat proteins from phylogenetically diverse bacteria share a common function in contact-dependent growth inhibition.

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Sigma-Aldrich
DAPI, for nucleic acid staining
Sigma-Aldrich
4′,6-Diamidino-2-phenylindole dihydrochloride, powder, BioReagent, suitable for cell culture, ≥98% (HPLC and TLC), suitable for fluorescence
Sigma-Aldrich
4′,6-Diamidino-2-phenylindole dihydrochloride, BioReagent, suitable for fluorescence, ≥95.0% (HPLC)