3wqb
Crystal structure of aeromonas sobria serine protease (ASP) and the chaperone (ORF2) complex
Structural highlights
FunctionASP_AERSO Exhibits serine protease activity (PubMed:11092244, PubMed:12153115, PubMed:16487335, PubMed:18067862, PubMed:18462393, PubMed:19654332). Preferentially cleaves the peptide bond following two basic residues, one of which is Lys, but does not recognize the bond following a single basic residue (PubMed:16487335). Probable potent virulence factor that cleaves various host plasma proteins, including prekallikrein, prothrombin and fibrinogen (PubMed:16487335, PubMed:17142774, PubMed:18067862, PubMed:18462393, PubMed:19654332). ASP induces vascular leakage and reduction in blood pressure by activating the host plasma kallikrein/kinin system (PubMed:12153115, PubMed:16487335, PubMed:17142774). It affects the host coagulation system during infection through activation of prothrombin to alpha-thrombin and degradation of fibrinogen, which impairs plasma clottability (PubMed:18067862, PubMed:18462393). It also hydrolyzes the complement component C5, releasing the C5a anaphylatoxin, which causes the formation of pus and edema (PubMed:18714034). In addition, degrades its external chaperone ORF2 after the secretion of the ASP-ORF2 complex (PubMed:25784551).[1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedSubtilisin-like proteases are broadly expressed in organisms ranging from bacteria to mammals. During maturation of these enzymes, N-terminal propeptides function as intramolecular chaperones, assisting the folding of their catalytic domains. However, we have identified an exceptional case, the serine protease from Aeromonas sobria (ASP), that lacks a propeptide. Instead, ORF2, a protein encoded just downstream of asp, appears essential for proper ASP folding. The mechanism by which ORF2 functions remains an open question, because it shares no sequence homology with any known intramolecular propeptide or other protein. Here we report the crystal structure of the ORF2-ASP complex and the solution structure of free ORF2. ORF2 consists of three regions: an N-terminal extension, a central body, and a C-terminal tail. Together, the structure of the central body and the C-terminal tail is similar to that of the intramolecular propeptide. The N-terminal extension, which is not seen in other subtilisin-like enzymes, is intrinsically disordered but forms some degree of secondary structure upon binding ASP. We also show that C-terminal (DeltaC1 and DeltaC5) or N-terminal (DeltaN43 and DeltaN64) deletion eliminates the ability of ORF2 to function as a chaperone. Characterization of the maturation of ASP with ORF2 showed that folding occurs in the periplasmic space and is followed by translocation into extracellular space and dissociation from ORF2, generating active ASP. Finally, a PSI-BLAST search revealed that operons encoding subtilases and their external chaperones are widely distributed among Gram-negative bacteria, suggesting that ASP and its homologs form a novel family of subtilases having an external chaperone. Structural Basis for Action of the External Chaperone for a Propeptide-deficient Serine Protease from Aeromonas sobria.,Kobayashi H, Yoshida T, Miyakawa T, Tashiro M, Okamoto K, Yamanaka H, Tanokura M, Tsuge H J Biol Chem. 2015 Apr 24;290(17):11130-43. doi: 10.1074/jbc.M114.622852. Epub, 2015 Mar 16. PMID:25784551[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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