6qf7
Crystal structures of the recombinant beta-Factor XIIa protease with bound Thr-Arg and Pro-Arg substrate mimetics
Structural highlights
DiseaseFA12_HUMAN Congenital factor XII deficiency;Hereditary angioedema type 3. Defects in F12 are the cause of factor XII deficiency (FA12D) [MIM:234000; also known as Hageman factor deficiency. This trait is an asymptomatic anomaly of in vitro blood coagulation. Its diagnosis is based on finding a low plasma activity of the factor in coagulating assays. It is usually only accidentally discovered through pre-operative blood tests. F12 deficiency is divided into two categories, a cross-reacting material (CRM)-negative group (negative F12 antigen detection) and a CRM-positive group (positive F12 antigen detection).[1] [2] [3] [4] [5] [6] [7] [8] [9] Defects in F12 are the cause of hereditary angioedema type 3 (HAE3) [MIM:610618; also known as estrogen-related HAE or hereditary angioneurotic edema with normal C1 inhibitor concentration and function. HAE is characterized by episodic local subcutaneous edema, and submucosal edema involving the upper respiratory and gastrointestinal tracts. HAE3 occurs exclusively in women and is precipitated or worsened by high estrogen levels (e.g. during pregnancy or treatment with oral contraceptives). It differs from HAE types 1 and 2 in that both concentration and function of C1 inhibitor are normal.[10] [11] FunctionFA12_HUMAN Factor XII is a serum glycoprotein that participates in the initiation of blood coagulation, fibrinolysis, and the generation of bradykinin and angiotensin. Prekallikrein is cleaved by factor XII to form kallikrein, which then cleaves factor XII first to alpha-factor XIIa and then trypsin cleaves it to beta-factor XIIa. Alpha-factor XIIa activates factor XI to factor XIa.[12] Publication Abstract from PubMedCoagulation factor XII (FXII) is a key initiator of the contact pathway, which contributes to inflammatory pathways. FXII circulates as a zymogen, which when auto-activated forms factor XIIa (FXIIa). Here, the production of the recombinant FXIIa protease domain (betaFXIIa(His)) with yields of approximately 1-2 mg per litre of insect-cell culture is reported. A second construct utilized an N-terminal maltose-binding protein (MBP) fusion (MBP-betaFXIIa(His)). Crystal structures were determined of MBP-betaFXIIa(His) in complex with the inhibitor D-Phe-Pro-Arg chloromethyl ketone (PPACK) and of betaFXIIa(His) in isolation. The betaFXIIa(His) structure revealed that the S2 and S1 pockets were occupied by Thr and Arg residues, respectively, from an adjacent molecule in the crystal. The Thr-Arg sequence mimics the P2-P1 FXIIa cleavage-site residues present in the natural substrates prekallikrein and FXII, and Pro-Arg (from PPACK) mimics the factor XI cleavage site. A comparison of the betaFXIIa(His) structure with the available crystal structure of the zymogen-like FXII protease revealed large conformational changes centred around the S1 pocket and an alternate conformation for the 99-loop, Tyr99 and the S2 pocket. Further comparison with activated protease structures of factors IXa and Xa, which also have the Tyr99 residue, reveals that a more open form of the S2 pocket only occurs in the presence of a substrate mimetic. The FXIIa inhibitors EcTI and infestin-4 have Pro-Arg and Phe-Arg P2-P1 sequences, respectively, and the interactions that these inhibitors make with betaFXIIa are also described. These structural studies of betaFXIIa provide insight into substrate and inhibitor recognition and establish a scaffold for the structure-guided drug design of novel antithrombotic and anti-inflammatory agents. Crystal structures of the recombinant beta-factor XIIa protease with bound Thr-Arg and Pro-Arg substrate mimetics.,Pathak M, Manna R, Li C, Kaira BG, Hamad BK, Belviso BD, Bonturi CR, Dreveny I, Fischer PM, Dekker LV, Oliva MLV, Emsley J Acta Crystallogr D Struct Biol. 2019 Jun 1;75(Pt 6):578-591. doi:, 10.1107/S2059798319006910. Epub 2019 Jun 4. PMID:31205020[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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