3H5C

X-Ray Structure of Protein Z-Protein Z Inhibitor Complex

Summary for 3H5C

• Entry DOI: 10.2210/pdb3h5c/pdb
• Descriptor: Protein Z-dependent protease inhibitor, Vitamin K-dependent protein Z, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: protein z-protein z inhibitor complex, blood coagulation, cleavage on pair of basic residues, disulfide bond, egf-like domain, gamma-carboxyglutamic acid, glycoprotein, hydroxylation, secreted, serine protease homolog, protease inhibitor, serine protease inhibitor, hydrolase inhibitor-blood clotting complex, hydrolase inhibitor/blood clotting
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 2
• Total formula weight: 85246.31

Authors

Dementiev, A.A.,Huang, X.,Olson, S.T.,Gettins, P.G.W. (deposition date: 2009-04-21, release date: 2010-04-28, Last modification date: 2024-11-27)

Primary citation

Huang, X.,Dementiev, A.,Olson, S.T.,Gettins, P.G.
Basis for the specificity and activation of the serpin protein Z-dependent proteinase inhibitor (ZPI) as an inhibitor of membrane-associated factor Xa.
J.Biol.Chem., 285:20399-20409, 2010

PubMed Abstract: The serpin ZPI is a protein Z (PZ)-dependent specific inhibitor of membrane-associated factor Xa (fXa) despite having an unfavorable P1 Tyr. PZ accelerates the inhibition reaction approximately 2000-fold in the presence of phospholipid and Ca(2+). To elucidate the role of PZ, we determined the x-ray structure of Gla-domainless PZ (PZ(DeltaGD)) complexed with protein Z-dependent proteinase inhibitor (ZPI). The PZ pseudocatalytic domain bound ZPI at a novel site through ionic and polar interactions. Mutation of four ZPI contact residues eliminated PZ binding and membrane-dependent PZ acceleration of fXa inhibition. Modeling of the ternary Michaelis complex implicated ZPI residues Glu-313 and Glu-383 in fXa binding. Mutagenesis established that only Glu-313 is important, contributing approximately 5-10-fold to rate acceleration of fXa and fXIa inhibition. Limited conformational change in ZPI resulted from PZ binding, which contributed only approximately 2-fold to rate enhancement. Instead, template bridging from membrane association, together with previously demonstrated interaction of the fXa and ZPI Gla domains, resulted in an additional approximately 1000-fold rate enhancement. To understand why ZPI has P1 tyrosine, we examined a P1 Arg variant. This reacted at a diffusion-limited rate with fXa, even without PZ, and predominantly as substrate, reflecting both rapid acylation and deacylation. P1 tyrosine thus ensures that reaction with fXa or most other arginine-specific proteinases is insignificant unless PZ binds and localizes ZPI and fXa on the membrane, where the combined effects of Gla-Gla interaction, template bridging, and interaction of fXa with Glu-313 overcome the unfavorability of P1 Tyr and ensure a high rate of reaction as an inhibitor.

PubMed: 20427285
DOI: 10.1074/jbc.M110.112748

Experimental method

X-RAY DIFFRACTION (3.26 Å)