Open AccessModulation of the K + efflux activity of Bacillus subtilis YhaU by YhaT and the C‐terminal region of YhaS
Author(s) -
Fujisawa Makoto,
Wada Yuko,
Ito Masahiro
Publication year - 2004
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00959-5
Subject(s) - bacillus subtilis , efflux , bacillales , modulation (music) , terminal (telecommunication) , chemistry , bacillaceae , physics , biology , biochemistry , bacteria , genetics , telecommunications , acoustics , computer science
The cation/proton antiporter 2 (CPA2) family is a large family of cation transporters and putative channel proteins that are found in bacteria, archaea as well as eukaryotes. Consistent with a K + efflux capacity that is found in several other CPA2 proteins, it is shown here that the YhaU protein of Bacillus subtilis greatly increased the concentration of K + required for growth of a K + uptake‐defective mutant of Escherichia coli . No YhaU‐dependent K + (Na + )/H + antiport activity was found in membrane vesicles. Two genes, yhaS and yhaT , are located upstream of yhaU and form an apparent operon with it. The YhaS protein has no reported homologues while the YhaT protein has sequence similarity to a sub‐domain of KTN proteins that are associated with potassium‐translocating channels and transporters. YhaT and the C‐terminal region of YhaS were shown to modulate the K + transport capacities of YhaU in complementation experiments. Expression studies, conducted by monitoring the β‐galactosidase levels in pMutin‐disrupted mutants of the yhaU locus, indicated that yhaU is strongly induced by alkaline pH‐ plus salt‐induced stress and that there are additional sodium‐specific responses of yhaS and yhaT .