The putative neuraminyllactose-binding hemagglutinin HpaA of Helicobacter pylori CCUG 17874 is a lipoprotein

Abstract

. 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. HpaA was not observed in the sarkosyl-insoluble outer membrane fraction. An isogenic mutant generated by insertional inactivation of hpaA was unaffected in its ability to bind four different human cell lines as well as fixed sections of gastric tissue and had hemagglutination properties identical to those of the wild type. The data collectively suggest that HpaA is a nonessential lipoprotein internal to the H. pylori cell and that it is not involved in adhesion.

Tip-α (hp0596 Gene Product) Is a Highly Immunogenic Helicobacter pylori Protein Involved in Colonization of Mouse Gastric Mucosa

“…Originally, the subcellular localization of both proteins was determined by cell fractionation followed by sarcosyl solubilization of inner membrane proteins. HpaA was found to be cytoplasmic and inner membrane situated, whereas Lpp20 was isolated from both the inner and the outer membrane fractions of H. pylori cells [25,40]. Further systematic examination, conducted by different methods, contradicted previous results and revealed that HpaA is a flagellar sheath protein and Lpp 20 is an outer membrane antigen released from cells inside membrane vesicles [17,21].…”

“…All our attempts to confirm the lipoprotein nature of Tip-a by growing H. pylori cells in the presence of labeled palmitic acid were unsuccessful. Similar difficulties were encountered by Kostrzynska et al and O'Toole et al during their work on H. pylori Lpp20 and HpaA [25,40].…”

Mutation of luxS affects motility and infectivity of Helicobacter pylori in gastric mucosa of a Mongolian gerbil model

“…H. pylori possesses several putative colonization factors, including flagella motility (Marshall & Warren, 1984), various adhesins (Evans et al, 1993;Falk et al, 1993;O'Toole et al, 1995), vacA (Salama et al, 2001) and urease (Marshall & Warren, 1984;Tsuda et al, 1994), some of which have been shown to be necessary for gastric colonization. Isogenic flaA 2 , flaB 2 and flaA flaB 2 mutant strains do not show full motility, and are unable to form effective colonies in the stomachs of germ-free piglets (Eaton et al, 1996).…”

Cloning, expression and purification of outer membrane protein PorA of Neisseria meningitidis serogroup B

“…The outer membrane proteins in Gram-negative bacteria have particular significance as a potential target for protective immunity [16]. Class 1 outer membrane protein (PorA) is a major component of the outer membrane of Neisseria meningitidis and functions as a cationic porin [17].…”