Affiliation:
1. University of California—Los Angeles and Wadsworth Veterans Affairs Medical Center, Los Angeles, California,1 and
2. Department of Molecular Biology, Byk Gulden Pharmaceuticals,2
3. Gesellschaft für Analyse-Technik und Consulting GmbH,3 and
4. Department of Chemistry, University of Konstanz,4 Konstanz, Germany
Abstract
ABSTRACT
The
cop
operons of
Helicobacter pylori
and
Helicobacter felis
were cloned by gene library screening. Both operons contain open reading frames for a P-type ion pump (CopA) with homology to Cd
2+
and Cu
2+
ATPases and a putative ion binding protein (CopP), the latter representing a CopZ homolog of the
copYZAB
operon of
Enterococcus hirae
. The predicted CopA ATPases contained an N-terminal GMXCXXC ion binding motif and a membrane-associated CPC sequence. A synthetic N-terminal peptide of the
H. pylori
CopA ATPase bound to Cu
2+
specifically, and gene disruption mutagenesis of CopA resulted in an enhanced growth sensitivity of
H. pylori
to Cu
2+
but not to other divalent cations. As determined experimentally,
H. pylori
CopA contains four pairs of transmembrane segments (H1 to H8), with the ATP binding and phosphorylation domains lying between H6 and H7, as found for another putative transition metal pump of
H. pylori
(K. Melchers, T. Weitzenegger, A. Buhmann, W. Steinhilber, G. Sachs, and K. P. Schäfer, J. Biol. Chem. 271:446–457, 1996). The corresponding transmembrane segments of the
H. felis
CopA pump were identified by hydrophobicity analysis and via sequence similarity. To define functional domains, similarly oriented regions of the two enzymes were examined for sequence identity. Regions with high degrees of identity included the N-terminal Cu
2+
binding domain, the regions of ATP binding and phosphorylation in the energy transduction domain, and a transport domain consisting of the last six transmembrane segments with conserved cysteines in H4, H6, and H7. The data suggest that
H. pylori
and
H. felis
employ conserved mechanisms of ATPase-dependent copper resistance.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
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