Direct analysis of the extracellular proteome from two strains of Helicobacter pylori

Abstract

Helicobacter pylori extracellular proteins are of interest because of possible roles in pathogenesis, host recognition, and vaccine development. We utilized a unique approach by growing two strains (including one nonsequenced strain) in a defined serum-free medium and directly analyzing the proteins present in the culture supernatants by LC-MS/MS. Over 125 proteins were identified in the extracellular proteomes of two H. pylori strains. Forty-five of these proteins were enriched in the extracellular fraction when compared to soluble cell-associated protein samples. Our analysis confirmed and expanded on the previously reported H. pylori extracellular proteome. Extracellular proteins of interest identified here included cag pathogenicity island protein Cag24 (CagD); proteases HP0657 and HP1012; a polysaccharide deacetylase, HP0310, possibly involved in the hydrolysis of acetyl groups from host N-acetylglucosamine residues or from residues on the cell surface; and HP0953, an uncharacterized protein that appears to be restricted to Helicobacter species that colonize the gastric mucosa. In addition, our analysis found eight previously unidentified outer membrane proteins and two lipoproteins that could be important cell surface proteins.

Helicobacter pyloridefense against oxidative attack

“…Although other studies have failed to detect Hp-Tpx extracellularly (89), this may reflect differences in growth conditions, as Tpx has been shown to have variable extracellular expression in other bacterial pathogens, depending on media composition and atmospheric oxygen concentration (38). While this condition-dependent expression variability has not been specifically assessed in H. pylori, mouse adaptation was associated with altered membrane expression of Hp-Tpx (108), suggesting that environmental changes can influence extracellular expression.…”

“…There is evidence that KapA may be involved in translocation of the catalase enzyme into the periplasmic space, as H. pylori KapA mutants had reduced catalase activity in the periplasmic fraction (45). In addition to its occurrence in the cytoplasm and periplasmic space, catalase has been characterized as a secreted protein (4,89) and an outer membrane protein (4,7,86), supporting a role for the enzyme in defense against exogenous ROS. H. pylori catalase is also present within outer membrane vesicles (77).…”

Complexomics Study of Two Helicobacter pylori Strains of Two Pathological Origins

“…The extracellular proteome from H. pylori was also investigated (60,151). Several studies examined the proteome of strains associated with different pathologies (47,48,79,80,128,131,143,(152)(153)(154)(155), most of them based on immunoproteomics methods.…”

“…Both of these proteins were reported to be among the 20 most abundant proteins in H. pylori and to be antigenic (48,79,119,128,129). NapA was found in the cytoplasm (120) and in the membrane (69) and is also secreted (60). RpL7/L12 was found both in the cytoplasm and membrane fractions (120,130).…”

“…Another TolC-like protein was identified in the H. pylori genome corresponding to JHP1382 (HELPY_1462) (56) and was shown to be active in efflux (57). MB12 is composed of HELPY_1462 and the secreted neutrophil-activating protein NapA (60). Therefore, it is tempting to speculate that the outer membrane efflux protein encoded by JHP1382 (HELPY_1462) participates in the secretion of NapA.…”