Collagenase

The mature protein has 4 domains; a metalloprotease domain (S1, approximately residues 111-786), S2 (877-882, equivalent to PKD), and 2 collagen-binding domains (CBD) S3a (997-1003) and S3b (1008-1118) (PubMed:11121400, PubMed:9922257). The S1 domain has collagen hydrolytic activity (PubMed:11121400, PubMed:18937627). The metalloprotease S1 domain is composed of 3 subdomains which together resemble a saddle; an activator domain (residues 119-388), the catalytic peptidase subdomain (398-670) and a helper subdomain (679-790) joined by a Gly-rich hinge (387-397) (PubMed:21947205, PubMed:23703618). The S2 domain (799-880, PKD) is flexible within a larger structure (S1 plus S2, residues 119-880) (PubMed:21871007, PubMed:21947205). Binding to Ca(2+) renders the midsection of S2 more flexible; Ca(2+) binding confers thermostability (PubMed:25760606). S3a and S3b each have collagen-binding activity; collagen is bound more efficiently when both S3a and S3b are present (PubMed:11121400). CBD S3a plus S3b binds to many types of collagen in vitro and in vivo (PubMed:11913772). The structure of CBD S3b becomes more compact and thermostable when it is bound to Ca(2+) and its N-terminal linker (approximately residues 1008-1020) changes from an extended alpha-helix to a beta-sheet anchored to the rest of the CBD (PubMed:12682007, PubMed:23144249). S3b may act as a Ca(2+)-activated molecular switch to trigger domain reorientation (PubMed:12682007). Isolated CBD S3b binds unidirectionally to the C-terminus of the collagen triple helix via a surface cleft (PubMed:19208618, PubMed:23144249). The S3b domain binds preferentially to undertwisted segions of collagen (PubMed:22898990).

Clostridial collagenases are among the most efficient degraders of eukaryotic collagen known; saprophytes use collagen as a carbon source while pathogens additionally digest collagen to aid in host colonization. Has both tripeptidylcarboxypeptidase on Gly-X-Y and endopeptidase activities; the endopeptidase cuts within the triple helix region of collagen while tripeptidylcarboxypeptidase successively digests the exposed ends, thus clostridial collagenases can digest large sections of collagen (PubMed:3002446). Active on soluble type I collagen, insoluble collagen, azocoll, soluble PZ-peptide (all collagenase substrates) and gelatin (PubMed:9922257). The full-length protein has collagenase activity, while the in vivo derived C-terminally truncated shorter versions only act on gelatin (PubMed:9922257). In vitro digestion of soluble calf skin collagen fibrils requires both ColG and ColH; ColG forms missing the second collagen-binding domain are also synergistic with ColH, although their overall efficiency is decreased (PubMed:18374061, PubMed:22099748). The activator domain (residues 119-388) and catalytic subdomain (389-670) open and close around substrate using a Gly-rich hinge (387-397), allowing digestion when the protein is closed (PubMed:21947205, PubMed:23703618). Binding of collagen requires Ca(2+) and is inhibited by EGTA; the collagen-binding domain (CBD, S3a plus S3b) specifically recognizes the triple-helical conformation made by 3 collagen protein chains in the triple-helical region (PubMed:11121400). Isolated CBD (S3a plus S3b) binds collagen fibrils and sheets of many tissues (PubMed:11913772).

Upon purification gives 67 kDa, 78 kDa, 82 kDa and 116 kDa (full-length) proteins all of which have the same N-terminus; only the longest form digests insoluble collagen (PubMed:9922257). At least 2 in vivo isolated forms (C1b and C1c) are missing the second collagen-binding domain, ending on Lys-1006 and Lys-1018 respectively (PubMed:22099748).

Belongs to the peptidase M9B family. Collagenase subfamily.

• Secreted

Collagenase ColG, Class I collagenase, Gelatinase ColG, Microbial collagenase

• swissprot:Q9X721

Enzymes

Oncology

126242Da