Affiliation:
1. Department of Microbiology and Immunology, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom,1 and
2. Department of Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, 9751 NN Haren, The Netherlands2
Abstract
ABSTRACT
When
Bacillus subtilis
is subjected to phosphate starvation, genes of the Pho regulon are either induced or repressed. Among those induced are genes encoding alkaline phosphatases (APases). A set of isogenic mutants, with a β-galactosidase gene transcriptionally fused to the inactivated target gene, was used to identify genes that influence the operation of the Pho regulon. One such gene was
nhaC
(previously
yheL
). In the absence of NhaC, growth and APase production were enhanced, while the production of other non-Pho-regulon secretory proteins (proteases and α-amylase) did not change. The influence of NhaC on growth, APase synthesis, and its own expression was dependent on the external Na
+
concentration. Other monovalent cations such as Li
+
or K
+
had no effect. We propose a role for NhaC in the uptake of Na
+
.
nhaC
appears to be encoded by a monocistronic operon and, contrary to previous reports, is not in the same transcriptional unit as
yheK
, the gene immediately upstream. The increase in APase production was dependent on an active PhoR, the sensor kinase of the two-component system primarily responsible for controlling the Pho regulon. Transcriptional fusions showed that the
phoPR
operon and both
phoA
(encoding APaseA) and
phoB
(encoding APaseB) were hyperinduced in the absence of NhaC and repressed when this protein was overproduced. This suggests that NhaC effects APase production via
phoPR
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
28 articles.
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