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1z6c
From Proteopedia
Revision as of 14:13, 3 May 2008
Solution structure of an EGF pair (EGF34) from vitamin K-dependent protein S
Overview
Vitamin K-dependent protein S is a cofactor of activated protein C, a serine protease that regulates blood coagulation. Deficiency of protein S can cause venous thrombosis. Protein S has four EGF domains in tandem; domains 2-4 bind calcium with high affinity whereas domains 1-2 mediate interaction with activated protein C. We have now solved the solution structure of the EGF3-4 fragment of protein S. The linker between the two domains is similar to what has been observed in other calcium-binding EGF domains where it provides an extended conformation. Interestingly, a disagreement between NOE and RDC data revealed a conformational heterogeneity within EGF3 due to a hinge-like motion around Glu186 in the Cys-Glu-Cys sequence, the only point in the domain where flexibility is allowed. The dominant, bent conformation of EGF3 in the pair has no precedent among calcium-binding EGF domains. It is characterized by a change in the psi angle of Glu186 from 160 degrees +/- 40 degrees , as seen in ten other EGF domains, to approximately 0 degrees +/- 15 degrees . NOESY data suggest that Tyr193, a residue not conserved in other calcium-binding EGF domains (except in the homologue Gas6), induces the unique fold of EGF3. However, SAXS data, obtained on EGF1-4 and EGF2-4, showed a dominant, extended conformation in these fragments. This may be due to a counterproductive domain-domain interaction between EGF2 and EGF4 if EGF3 is in a bent conformation. We speculate that the ability of EGF3 to adopt different conformations may be of functional significance in protein-protein interactions involving protein S.
About this Structure
1Z6C is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Solution structure of the Ca2+-Binding EGF3-4 pair from vitamin K-dependent protein S: identification of an unusual fold in EGF3., Drakenberg T, Ghasriani H, Thulin E, Thamlitz AM, Muranyi A, Annila A, Stenflo J, Biochemistry. 2005 Jun 21;44(24):8782-9. PMID:15952784 Page seeded by OCA on Sat May 3 17:13:37 2008
