1vcp
SEMLIKI FOREST VIRUS CAPSID PROTEIN (CRYSTAL FORM I)
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OverviewOverview
Alphaviruses are enveloped, insect-borne viruses, which contains a, positive-sense RNA genome. The protein capsid is surrounded by a lipid, membrane, which is penetrated by glycoprotein spikes. The structure of the, Sindbis virus (SINV) (the type virus) core protein (SCP) was previously, determined and found to have a chymotrypsin-like structure. SCP is a, serine proteinase which cleaves itself from a polyprotein. Semliki Forest, virus (SFV) is among the most distantly related alphaviruses to SINV., Similar to SCP, autocatalysis is inhibited in SFCP after cleavage of the, polyprotein by leaving the carboxy-terminal tryptophan in the specificity, pocket. The structures of two different crystal forms (I and II) of SFV, core protein (SFCP) have been determined to 3.0 A and 3.3 A resolution, respectively. The SFCP monomer backbone structure is very similar to that, of SCP. The dimeric association between monomers, A and B, found in two, different crystal forms of SCP is also present in both crystal forms of, SFCP. However, a third monomer, C, occurs in SFCP crystal form I. While, monomers A and B make a tail-to-tail dimer contact, monomers B and C make, a head-to-head dimer contact. A hydrophobic pocket on the surface of the, capsid protein, the proposed site of binding of the E2 glycoprotein, has, large conformational differences with respect to SCP and, in contrast to, SCP, is found devoid of bound peptide. In particular, Tyr184 is pointing, out of the hydrophobic pocket in SFCP, whereas the equivalent tyrosine in, SCP is pointing into the pocket. The conformation of Tyr184, found in, SFCP, is consistent with its availability for iodination, as observed in, the homologous SINV cores. This suggests, by comparison with SCP, that E2, binding to cores causes major conformational changes, including the burial, of Tyr184, which would stabilize the intact virus on budding from an, infected cell. The head-to-tail contacts found in the pentameric and, hexameric associations within the virion utilize in the same monomer, surface regions as found in the crystalline dimer interfaces.
About this StructureAbout this Structure
1VCP is a Single protein structure of sequence from Semliki forest virus with HG as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Structure of Semliki Forest virus core protein., Choi HK, Lu G, Lee S, Wengler G, Rossmann MG, Proteins. 1997 Mar;27(3):345-59. PMID:9094737
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