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Stress response of porphyromonas gingivalis Lu, Biqing


The heat shock response of Porphyromonas gingivalis was examined by one-and two-dimensional polyacrylamide gel electrophoresis after metabolic labeling with (14C)-amino acids. When P. gingivalis cells were shifted from 37°C to 42°C, elevated synthesis of four proteins with the apparent molecular weight of 92, 80, 74, and 62kDa was observed, whereas synthesis of a 50kDa protein decreased during heat shock. The 74 and 62kDa proteins were identified as homologs of E. coli DnaK and GroEL respectively by Western immunoblotting. On two-dimensional Western blots, two forms of DnaK and four forms of GroEL were identified due to their slightly different isoelectric points. dnaK and groEL gene homologs were identified in several P. gingivalis and some other black-pigmented Bacteroides strains by Southern hybridization. DnaK and GroEL homolog proteins and some other proteins were also induced when P. gingivalis cells were challenged by ethanol. Exposure to oxidative stress and an elevation or decrease in pH did not show a discernible induction of these heat shock proteins. GroEL and DnaK homolog proteins were not induced in P. gingivalis cells recovered from a guinea-pig infection model.

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