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J. Bacteriol., Nov 1995, 6049-6057, Vol 177, No. 21
PW O'Toole, L Janzon, P Doig, J Huang, M Kostrzynska and TJ Trust
The ability of certain strains of Helicobacter pylori to cause sialic
acid-sensitive agglutination of erythrocytes has been attributed to the
HpaA protein (D.G. Evans, T.K. Karjalainen, D. J. Evans, Jr., D. Y. Graham,
and C.H. Lee, J. Bacteriol. 175:674-683, 1993), the gene for which has been
cloned and sequenced. On the basis of the hydropathy plot of HpaA and the
presence of a potential lipoprotein signal sequence and modification site,
and because of the similarities of these features with those of the cell
envelope lipoprotein Lpp20 of H. pylori, we examined the possibility that
HpaA was also a lipoprotein. Posttranslational processing of the HpaA
protein expressed by the cloned gene was sensitive to globomycin, an
inhibitor of the lipoprotein-specific signal peptidase II. Antibodies
raised to the putative sialic acid-binding region of HpaA failed to bind to
the surface of H. pylori cells in immunoelectron microscopy but instead
were observed to have labeled the cytoplasm when thin sections were
examined. This antibody recognized a 29,000-M(r) protein in Western blots
(immunoblots) of cell extracts of H. pylori and Escherichia coli cells
expressing the cloned hpaA gene. Determination of the sequence of hpaA from
strain CCUG 17874 indicated significant differences from that determined by
Evans and coworkers in the above-mentioned study, including extension of
the gene into the open reading frame 3 downstream of hpaA to produce a
protein with an M(r) of 26,414. Localization of HpaA indicated that it was
predominantly located in the cytoplasmic fraction of the cell in both E.
coli and H. pylori.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
The putative neuraminyllactose-binding hemagglutinin HpaA of Helicobacter pylori CCUG 17874 is a lipoprotein
Astra Arcus AB, Sodertalje, Sweden.
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