Degradation of Host Heme Proteins by Lysine- and Arginine-Specific Cysteine Proteinases (Gingipains) of Porphyromonas gingivalis

AUTOR(ES)

Sroka, Aneta

FONTE

American Society for Microbiology

RESUMO

Porphyromonas gingivalis can use hemoglobin bound to haptoglobin and heme complexed to hemopexin as heme sources; however, the mechanism by which hemin is released from these proteins has not been defined. In the present study, using a variety of analytical methods, we demonstrate that lysine-specific cysteine proteinase of P. gingivalis (gingipain K, Kgp) can efficiently cleave hemoglobin, hemopexin, haptoglobin, and transferrin. Degradation of hemopexin and transferrin in human serum by Kgp was also detected; however, we did not observe extensive degradation of hemoglobin in serum by Kgp. Likewise the β-chain of haptoglobin was partially protected from degradation by Kgp in a haptoglobin-hemoglobin complex. Arginine-specific gingipains (gingipains R) were also found to degrade hemopexin and transferrin in serum; however, this was observed only at relatively high concentrations of these enzymes. Growth of P. gingivalis strain A7436 in a minimal media with normal human serum as a source of heme correlated not only with the ability of the organism to degrade hemoglobin, haptoglobin, hemopexin, and transferrin but also with an increase in gingipain K and gingipain R activity. The ability of gingipain K to cleave hemoglobin, haptoglobin, and hemopexin may provide P. gingivalis with a useable source of heme for growth and may contribute to the proliferation of P. gingivalis within periodontal pockets in which erythrocytes are abundant.

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