1cd3
|
PROCAPSID OF BACTERIOPHAGE PHIX174
OverviewOverview
An empty precursor particle called the procapsid is formed during assembly, of the single-stranded DNA bacteriophage phiX174. Assembly of the phiX174, procapsid requires the presence of the two scaffolding proteins, D and B, which are structural components of the procapsid, but are not found in the, mature virion. The X-ray crystallographic structure of a "closed", procapsid particle has been determined to 3.5 A resolution. This structure, has an external scaffold made from 240 copies of protein D, 60 copies of, the internally located B protein, and contains 60 copies of each of the, viral structural proteins F and G, which comprise the shell and the 5-fold, spikes, respectively. The F capsid protein has a similar conformation to, that seen in the mature virion, and differs from the previously determined, 25 A resolution electron microscopic reconstruction of the "open", procapsid, in which the F protein has a different conformation. The D, scaffolding protein has a predominantly alpha-helical fold and displays, remarkable conformational variability. We report here an improved and, refined structure of the closed procapsid and describe in some detail the, differences between the four independent D scaffolding proteins per, icosahedral asymmetric unit, as well as their interaction with the F, capsid protein. We re-analyze and correct the comparison of the closed, procapsid with the previously determined cryo-electron microscopic image, reconstruction of the open procapsid and discuss the major structural, rearrangements that must occur during assembly. A model is proposed in, which the D proteins direct the assembly process by sequential binding and, conformational switching.
About this StructureAbout this Structure
1CD3 is a Protein complex structure of sequences from Enterobacteria phage phix174. The following page contains interesting information on the relation of 1CD3 with [Bacteriophage phiX174]. Full crystallographic information is available from OCA.
ReferenceReference
The role of scaffolding proteins in the assembly of the small, single-stranded DNA virus phiX174., Dokland T, Bernal RA, Burch A, Pletnev S, Fane BA, Rossmann MG, J Mol Biol. 1999 May 14;288(4):595-608. PMID:10329166
Page seeded by OCA on Sun Nov 18 08:58:14 2007