Affiliation:
1. Department of Microbiology, Cornell University, Ithaca, New York 14853-8101
2. Experimental Station E328/148B, DuPont Central Research and Development, Wilmington, Delaware 19880
Abstract
ABSTRACT
The
Bacillus subtilis
zinc uptake repressor (Zur) regulates genes involved in zinc uptake. We have used DNA microarrays to identify genes that are derepressed in a
zur
mutant. In addition to members of the two previously identified Zur-regulated operons (
yciC
and
ycdHI-yceA
), we identified two other genes,
yciA
and
yciB
, as targets of Zur regulation. Electrophoretic mobility shift experiments demonstrated that all three operons are direct targets of Zur regulation. Zur binds to an ∼28-bp operator upstream of the
yciA
gene, as judged by DNase I footprinting, and similar operator sites are found preceding each of the previously described target operons,
yciC
and
ycdHI-yceA
. Analysis of a
yciA
-
lacZ
fusion indicates that this operon is induced under zinc starvation conditions and derepressed in the
zur
mutant. Phenotypic analyses suggest that the YciA, YciB, and YciC proteins may function as part of the same Zn(II) transport pathway. Mutation of
yciA
or
yciC
, singly or in combination, had little effect on growth of the wild-type strain but significantly impaired the growth of the
ycdH
mutant under conditions of zinc limitation. Since the YciA, YciB, and YciC proteins are not obviously related to any known transporter family, they may define a new class of metal ion uptake system. Mutant strains lacking all three identified zinc uptake systems (
yciABC
,
ycdHI-yceA
, and
zosA
) are dependent on micromolar levels of added zinc for optimal growth.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
107 articles.
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