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J. Bacteriol., Aug 1997, 4970-4976, Vol 179, No. 16
Z Ge and DE Taylor
The Helicobacter pylori pss gene, coding for phosphatidylserine synthase
(PSS), was cloned and sequenced in this study. A polypeptide of 237 amino
acids was deduced from the PSS sequence. H. pylori PSS exhibits significant
amino acid sequence identity with the PSS proteins found in the
archaebacterium Methanococcus jannaschii, the gram- positive bacterium
Bacillus subtilis, and the yeast Saccharomyces cerevisiae but none with its
Escherichia coli counterpart. Expression of the putative pss gene in
maxicells gave rise to a product of approximately 26 kDa, which is in
agreement with the predicted molecular mass of 26,617 Da. A
manganese-dependent PSS activity was found in the membrane fractions of the
E. coli cells overexpressing the H. pylori pss gene product. This result
indicates that this enzyme is a membrane-bound protein, a conclusion which
is supported by the fact that the PSS protein contains several local
hydrophobic segments which could form transmembrane helices. The pss gene
was inactivated with a chloramphenicol acetyltransferase cassette on the
plasmid. However, an isogenic pss gene-disrupted mutant of H. pylori UA802
could not be obtained, suggesting that this enzyme plays an essential role
in the growth of this organism.
Copyright © 1997, American Society for Microbiology
The Helicobacter pylori gene encoding phosphatidylserine synthase: sequence, expression, and insertional mutagenesis
Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada.
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