Fibrinogen variant BβD432A has normal polymerization but does not bind knob “B”
- 30 April 2009
- journal article
- Published by American Society of Hematology in Blood
- Vol. 113 (18), 4425-4430
- https://doi.org/10.1182/blood-2008-09-178178
Abstract
Fibrinogen residue Bβ432Asp is part of hole “b” that interacts with knob “B,” whose sequence starts with Gly-His-Arg-Pro-amide (GHRP). Because previous studies showed BβD432A has normal polymerization, we hypothesized that Bβ432Asp is not critical for knob “B” binding and that new knob-hole interactions would compensate for the loss of this Asp residue. To test this hypothesis, we solved the crystal structure of fragment D from BβD432A. Surprisingly, the structure (rfD-BβD432A+GH) showed the peptide GHRP was not bound to hole “b.” We then re-evaluated the polymerization of this variant by examining clot turbidity, clot structure, and the rate of FXIIIa cross-linking. The turbidity and the rate of γ-γ dimer formation for BβD432A were indistinguishable compared with normal fibrinogen. Scanning electron microscopy showed no significant differences between the clots of BβD432A and normal, but the thrombin-derived clots had thicker fibers than clots obtained from batroxobin, suggesting that cleavage of FpB is more important than “B:b” interactions. We conclude that hole “b” and “B:b” knob-hole binding per se have no influence on fibrin polymerization.Keywords
This publication has 40 references indexed in Scilit:
- Direct Evidence for Specific Interactions of the Fibrinogen αC-Domains with the Central E Region and with Each OtherBiochemistry, 2007
- BβGlu397 and BβAsp398 but Not BβAsp432 Are Required for “B:b” Interactions,Biochemistry, 2004
- Analysis of Engineered Fibrinogen Variants Suggests That an Additional Site Mediates Platelet Aggregation and That “B−b” Interactions Have a Role in Protofibril FormationBiochemistry, 2002
- Use of TLS parameters to model anisotropic displacements in macromolecular refinementActa Crystallographica Section D-Structural Biology, 2001
- Conformational Changes in Fragments D and Double-D from Human Fibrin(ogen) upon Binding the Peptide Ligand Gly-His-Arg-Pro-Amide,Biochemistry, 1999
- Refinement of Macromolecular Structures by the Maximum-Likelihood MethodActa crystallographica. Section D, Structural biology, 1997
- [20] Processing of X-ray diffraction data collected in oscillation modeMethods in Enzymology, 1997
- The CCP4 suite: programs for protein crystallographyActa crystallographica. Section D, Structural biology, 1994
- Role of the .alpha.C Domains of Fibrin in Clot FormationBiochemistry, 1994
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970