Analyses of a Bacillus subtilis homologue of the Na+/H+ antiporter gene which is important for pH homeostasis of alkaliphilic Bacillus sp. C-125

Bacillus subtilis was revealed to have a homologous region to the DNA fragm ent responsible for alkaliphily of alkaliphilic Bacillus sp. C-125 on the g enome, as reported previously [1]. The yufT gene on the B. subtilis genome showed a significant similarity with ORF1 of Bacillus sp. C-125, which is r elated to membrane potential (Delta Psi)-driven Na+/H+ antiport activity an d is important for pH homeostasis in an alkaline condition. Disruption of t he yufT gene resulted in the decrease of Na+/H+ antiport activity, and the growth of the yufT disrupted strain was impaired with an increase in the ex ternal Na+ concentration. We conclude that the yufT gene encodes a Na+/H+ a ntiporter, which has a dominant role in the extrusion of cytotoxic Na+. (C) 1999 Elsevier Science B.V. All rights reserved.