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Regulatory network of lipopolysaccharide O‐antigen biosynthesis in Yersinia enterocolitica includes cell envelope‐dependent signals
Author(s) -
Bengoechea José Antonio,
Zhang Lijuan,
Toivanen Paavo,
Skurnik Mikael
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02940.x
Subject(s) - biology , lipid a , yersinia enterocolitica , promoter , transcription factor , lipopolysaccharide , microbiology and biotechnology , tlr2 , transcription (linguistics) , antigen , antiporter , gene , biochemistry , gene expression , signal transduction , bacteria , genetics , tlr4 , immunology , membrane , linguistics , philosophy
Summary Lipopolysaccharide (LPS) is a glycolipid present in the outer membrane of all Gram‐negative bacteria, and it is one of the signature molecules recognized by the receptors of the innate immune system. In addition to its lipid A portion (the endotoxin), its O‐chain polysaccharide (the O‐antigen) plays a critical role in the bacterium–host interplay and, in a number of bacterial pathogens, it is a virulence factor. We present evidence that, in Yersinia enterocolitica serotype O:8, a complex signalling network regulates O‐antigen expression in response to temperature. Northern blotting and reporter fusion analyses indicated that temperature regulates the O‐antigen expression at the transcriptional level. Promoter cloning showed that the O‐antigen gene cluster contains two transcriptional units under the control of promoters P wb1 and P wb2 . The activity of both promoters is under temperature regulation and is repressed in bacteria grown at 37 ° C. We demonstrate that the RosA/RosB efflux pump/potassium antiporter system and Wzz, the O‐antigen chain length determinant, are indirectly involved in the regulation mainly affecting the activity of promoter P wb2 . The rosAB transcription, under the control of P ros , is activated at 37 ° C, and P wb2 is repressed through the signals generated by the RosAB system activation, i.e. decreased [K + ] and increased [H + ]. The wzz transcription is under the control of P wb2 , and we show that, at 37 ° C, overexpression of Wzz downregulates slightly the P wb1 and P wb2 activities and more strongly the P ros activity, with the net result that more O‐antigen is produced. Finally, we demonstrate that overexpression of Wzz causes membrane stress that activates the CpxAR two‐component signal transduction system.