Periodontopathogens interfere with the human renin-angiotensin system through a surface-attached protease
The renin-angiotensin system (RAS) executes its functions through biologically active peptides, angiotensins (Ang). Angiotensinogen-derived precursor, Ang I is cleaved by angiotensin-converting enzyme (ACE) into proinflammatory Ang II, which increases blood pressure. In the alternate pathway performed by neprilysin and ACE II, Ang 1-7 is produced from Ang I with activities opposite to Ang II. Here, we show that Porphyromonas gingivalis (Pg) and Tannerella forsythia (Tf), endogenous oral pathogens, direct RAS into generation of Ang 1-7 through endopeptidases O, PgPepO and TfPepO, respectively. PepOs are thermophilic metalloproteases inhibited by cation chelators, but not by specific ACE and neprilysin inhibitors. PgPepO and TfPepO prefer large hydrophobic amino acids at the carbonyl side of scissile peptide bonds (P1 position), and TfPepO, contrary to all known homologous proteases, hydrolyzes substrates away from both terminuses. Solved crystal structures show that exceptionally wide entrance to the catalytic cleft explains unique properties of TfPepO. Furthermore, the different nature of subsites S1 and S2 in the substrate binding site explains refractory of PepOs to inhibitors of human homologous proteases. Multiple immunoassays clearly show that PepOs are attached to the bacteria cell surface and are released in outer membrane vesicles. Moreover, PepO is responsible for Ang I hydrolysis by Pg and Tf. Finally, PepO deletion reduced only the virulence of Tf in the Galleria mellonella model. Thus, our data show that Pg and Tf interfere with RAS through a PepO protease.