Surface-Associated Heat Shock Proteins ofLegionella pneumophilaandHelicobacter pylori:Roles in Pathogenesis and Immunity

Bacterial heat shock proteins (Hsps) are abundantly produced during the course of most microbial infections and are often targeted by the mammalian immune response. While Hsps have been well characterized for their roles in protein folding and secretion activities, little attention has been given to their participation in pathogenesis. In the case ofLegionella pneumophila, an aquatic intracellular parasite of protozoa and cause of Legionnaires' disease, Hsp60 is uniquely located in the periplasm and on the bacterial surface. Surface-associated Hsp60 promotes attachment and invasion in a HeLa cell model and may alter an early step associated with the fusion of phagosomes with lysosomes. Avirulent strains ofL. pneumophilacontaining defined mutations in severaldot/icmgenes are defective in localizing Hsp60 onto their surface and are reduced approximately 1000-fold in their invasiveness towards HeLa cells. For the ulcer-causing bacteriumHelicobacter pylori, surfaceassociated Hsp60 and Hsp70 mediate attachment to gastric epithelial cells. The increased expression of these Hsps following acid shock correlates with both increased association with and inflammation of the gastric mucosa. A role for Hsps in colonization, mucosal infection and in promoting inflammation is discussed. Infect. Dis. Obstet. Gynecol. 7:58–63, 1999.

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Heat-shock response in Legionella pneumophila

Canadian Journal of Microbiology ◽

10.1139/m88-202 ◽

1988 ◽

Vol 34 (10) ◽

pp. 1148-1153 ◽

Cited By ~ 11

Author(s):

Michael W. Lema ◽

Arnold Brown ◽

Charles A. Butler ◽

Paul S. Hoffman

Keyword(s):

Heat Shock ◽

Heat Shock Proteins ◽

Legionella Pneumophila ◽

Heat Shock Response ◽

Temperature Shift ◽

Bacterial Cells ◽

Groel Protein ◽

Shock Response ◽

Molecular Masses ◽

Shock Proteins

The heat-shock response of Legionella pneumophila was examined by radiolabelling bacterial cell proteins with [35S]methionine following a temperature shift from 30 to 42 °C. Five heat-shock proteins were identified as having molecular masses of 17, 60, 70, 78, and 85 kilodaltons (kDa). The 85- and 60-kDa proteins were equally distributed between supernatant and pellet fractions following ultracentrifugation at 100 000 × g, the 70- and 78-kDa proteins were found primarily in the supernatant, and the 17-kDa protein was found primarily in the pellet. Synthesis of subsets of the heat-shock proteins could be stimulated by novobiocin, patulin, or puromycin. Ethanol, an effector of the heat-shock response in other microorganisms, had little effect on L. pneumophila, even at the highest concentration tolerated by the bacterial cells (1.9%). Finally, the 60-kDa heat-shock protein of L. pneumophila was immunologically cross-reactive with a polyclonal antibody prepared to the Escherichia coli groEL protein. However, a mouse monoclonal antibody reactive with the 60-kDa protein of all legionellae tested did not cross-react with the E. coli groEL protein, suggesting that the Legionella 60-kDa protein contains common and unique epitopes.

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