Evidence for Specific Secretion Rather than Autolysis in the Release of Some Helicobacter pylori Proteins

Abstract

We investigated whether Helicobacter pylori cells actively secrete proteins such as the urease subunits UreA and UreB and the GroES and GroEL homologs HspA and HspB or whether these proteins were present in the extracellular compartment as a consequence of autolysis. Using a subcellular fractionation approach associated with quantitative Western blot analyses, we showed that the supernatant protein profiles were very different from those of the cell pellets, even for bacteria harvested in the late growth phase; this suggests that the release process is selective. A typical cytoplasmic protein, a β-galactosidase homolog, was found exclusively associated with the pellet of whole-cell extracts, and no traces were found in the supernatant. In contrast, UreA, UreB, HspA, and HspB were mostly found in the pellet but significant amounts were also present in the supernatant. HspA and UreB were released into the supernatant at the same rate throughout the growth phase (3%), whereas large portions of HspB and UreA were released during the stationary phase (over 30 and 20%, respectively) rather than during the early growth phase (20% and 6, respectively). The profiles of protein obtained after water extraction of the bacteria with those of the proteins naturally released within the liquid culture supernatants demonstrated that water extraction led to the release of a large amount of protein due to artifactual lysis. Our data support the conclusion that a specific and selective mechanism(s) is involved in the secretion of some H. pylori antigens. A programmed autolysis process does not seem to make a major contribution.

Prospective study of Helicobacter pylori antigens and gastric noncardia cancer risk in the nutrition intervention trial cohort

“…The molecular chaperone GroEL was also previously identified as a marker of gastric cancer risk in a German study 8 and is proposed to influence the binding of the bacterium to the gastrointestinal mucosa. 26,27 HcpC belongs to the family of Helicobacter cysteine-rich proteins that induce proinflammatory cytokines 28 and it has previously been associated with chronic atrophic gastritis. 9 While our risk prediction analysis was purely exploratory, it is interesting to note that models using the multiplex data performed relatively well and were in general agreement with results of disease association models.…”

The GroEL-like protein from Campylobacter rectus: immunological characterization and interleukin-6 and -8 induction in human gingival fibroblast

“…In H. pylori, HspB (GroEL homologue) is released by bacterial autolysis and becomes adsorbed to the surface of intact bacteria in vitro, and this mechanism also seems to be present in vivo when human gastric biopsies are examined [16,17]. On the other hand, Vanet and Labigne [18] concluded that secretion of HspB did not occur by a programmed autolysis process but by a speci¢c and selective mechanism. Signi¢cant enhancement of IL-6 production by C. rectus LPS has been reported [19].…”

Immunisation with non-integral OMPs promotes pulmonary clearance ofPseudomonas aeruginosa

“…Su⁄cient protein was puri¢ed from P. aeruginosa to carry out a study of immune-speci¢c responses to six proteins of molecular masses equivalent to 13,16,20,40,45 and 80 kDA, as shown in Fig. 1.…”