1aa0
From Proteopedia
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FIBRITIN DELETION MUTANT E (BACTERIOPHAGE T4)
Overview
BACKGROUND: Oligomeric coiled-coil motifs are found in numerous protein, structures; among them is fibritin, a structural protein of bacteriophage, T4, which belongs to a class of chaperones that catalyze a specific, phage-assembly process. Fibritin promotes the assembly of the long tail, fibers and their subsequent attachment to the tail baseplate; it is also a, sensing device that controls the retraction of the long tail fibers in, adverse environments and, thus, prevents infection. The structure of, fibritin had been predicted from sequence and biochemical analyses to be, mainly a triple-helical coiled coil. The determination of its structure at, atomic resolution was expected to give insights into the assembly process, and biological function of fibritin, and the properties of modified, coiled-coil structures in general. RESULTS: The three-dimensional, structure of fibritin E, a deletion mutant of wild-type fibritin, was, determined to 2.2 A resolution by X-ray crystallography. Three identical, subunits of 119 amino acid residues form a trimeric parallel coiled-coil, domain and a small globular C-terminal domain about a crystallographic, threefold axis. The coiled-coil domain is divided into three segments that, are separated by insertion loops. The C-terminal domain, which consists of, 30 residues from each subunit, contains a beta-propeller-like structure, with a hydrophobic interior. CONCLUSIONS: The residues within the, C-terminal domain make extensive hydrophobic and some polar intersubunit, interactions. This is consistent with the C-terminal domain being, important for the correct assembly of fibritin, as shown earlier by, mutational studies. Tight interactions between the C-terminal residues of, adjacent subunits counteract the latent instability that is suggested by, the structural properties of the coiled-coil segments. Trimerization is, likely to begin with the formation of the C-terminal domain which, subsequently initiates the assembly of the coiled coil. The interplay, between the stabilizing effect of the C-terminal domain and the labile, coiled-coil domain may be essential for the fibritin function and for the, correct functioning of many other alpha-fibrous proteins.
About this Structure
1AA0 is a Single protein structure of sequence from Bacteriophage t4 with CL and ZN as ligands. Full crystallographic information is available from OCA.
Reference
Structure of bacteriophage T4 fibritin: a segmented coiled coil and the role of the C-terminal domain., Tao Y, Strelkov SV, Mesyanzhinov VV, Rossmann MG, Structure. 1997 Jun 15;5(6):789-98. PMID:9261070
Page seeded by OCA on Tue Nov 20 10:42:43 2007
