title: Carboxypeptidase activity common to viridans group streptococci cleaves angiotensin I to angiotensin II: an activity homologous to angiotensin-converting enzyme (ACE).
abstract: We have found that Streptococcus gordonii FSS2, an infective endocarditis (IE) isolate, expresses a dipeptidyl-carboxypeptidase with activity homologous to angiotensin-converting enzyme (ACE). The carboxypeptidase activity was purified to homogeneity as a complex/aggregate from a bacterial surface extract and was also active as a 165 kDa monomer. The specific activity for the carboxypeptidase activity was eightfold higher than that for recombinant human ACE. Selected ACE inhibitors, captopril, lisinopril and enalapril, did not inhibit the ACE activity. The carboxypeptidase also hydrolysed the Aα and Bβ-chains of human fibrinogen, which resulted in impaired fibrin formation by thrombin. The gene encoding ACE carboxypeptidase activity was sequenced and the inferred polypeptide product showed 99 % amino acid homology to SGO_0566, sgc, 'challisin' of S. gordonii CL1 Challis, and had no significant amino acid sequence homology to human ACE. Homologues of challisin ACE activity were commonly detected among the viridans group streptococci most often associated with IE.
authors.affiliation: Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, Wentworthville, NSW 2145, Australia.
authors.forename: Derek W S
authors.initials: DWS
authors.lastname: Harty
authors.affiliation: Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, Wentworthville, NSW 2145, Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Hunter
mesh_terms: D000803:Angiotensin I / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D001483:Base Sequence; D002216:Captopril / Q000494:pharmacology; D002268:Carboxypeptidases / Q000302:isolation & purification / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004656:Enalapril / Q000494:pharmacology; D004697:Endocarditis, Bacterial / Q000382:microbiology; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D017706:Lisinopril / Q000494:pharmacology; D008969:Molecular Sequence Data; D007703:Peptidyl-Dipeptidase A / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D013290:Streptococcal Infections / Q000382:microbiology; D054773:Streptococcus gordonii / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D004656:Enalapril; D005340:Fibrinogen; D000803:Angiotensin I; D002216:Captopril; D017706:Lisinopril; D002268:Carboxypeptidases; D007703:Peptidyl-Dipeptidase A