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A novel device of bacterial signal transducers.
Author(s) -
Ishige K.,
Nagasawa S.,
Tokishita S.,
Mizuno T.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06850.x
Subject(s) - response regulator , biology , histidine kinase , histidine , kinase , signal transduction , phosphorylation , function (biology) , regulator , two component regulatory system , microbiology and biotechnology , biochemistry , genetics , gene , amino acid , mutant
The osmoregulatory expression of ompC and ompF in Escherichia coli is mediated by a pair of bacterial signal transduction proteins, EnvZ (sensory kinase) and OmpR (response regulator). We isolated previously multicopy suppressors which can complement a defect in the phosphotransfer signal transduction caused by an envZ deletion mutation. Among such suppressors, arcB and barA are of particular interest because these gene products are unique in the sense that they contain both an autophosphorylated histidine site (or transmitter module) and a phospho‐accepting aspartate site (or receiver module) in their primary amino acid sequences. Here we report that ArcB and BarA possess in the C‐terminal region a phosphorylated histidine site which has never been noticed, in addition to the authentic one identified previously. This newly identified histidine in ArcB and BarA was demonstrated to play a crucial role in the observed multicopy suppression. Furthermore, it was demonstrated in vivo and in vitro for ArcB that the C‐terminal domain containing the histidine can function as an alternative phosphodonor (or transmitter). This novel type of sensory kinase was therefore revealed to contain two independent phosphodonor sites, together with a phospho‐accepting site. These findings suggest that this unique feature of ArcB and BarA, in terms of the signaling modules, make it possible for these sensory kinases to function as dual‐signaling transducers.