Enterohaemorrhagic Escherichia coli O157:H7 harbours a cryptic plasmid, pOSAK1, that carries only three ORFs: mobA (involved in plasmid mobilization), ORF1 and ORF2. Predicted proteins encoded by these two ORFs were found to share a weak homology with RnlA and RnlB, respectively, a toxin–antitoxin system encoded on the E. coli K-12 chromosome. Here, we report that lsoA (ORF1) encodes a toxin and lsoB (ORF2) an antitoxin.
In spite of the homologies, RnlB and LsoB functioned as antitoxins against only their cognate toxins and not interchangeably with each other. Interestingly, T4 phage Dmd suppressed the toxicities of both RnlA and LsoA by direct interaction, the first example of a phage with an antitoxin against multiple toxins.
2012-03-08
Eng.
Molecular microbiology
Department of Biological sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho,Toyonaka-shi, Osaka 560-0043, Japan.
Mol Microbiol. 2012 Feb;83(4):669-81
© Galenicom 1999-2013