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2jub
From Proteopedia
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Solution structure of IPI*
Overview
Phage T4 protects its DNA from the two-gene-encoded gmrS/gmrD, (glucose-modified hydroxymethylcytosine restriction endonuclease) CT of, pathogenic Escherichia coli, CT596, by injecting several hundred copies of, the 76-amino-acid-residue nuclease inhibitor, IPI*, into the infected, host. Here, the three-dimensional solution structure of mature IPI* is, reported as determined by nuclear magnetic resonance techniques using 1290, experimental nuclear Overhauser effect and dipolar coupling constraints (, approximately 17 constraints per residue). Close examination of this, oblate-shaped protein structure reveals a novel fold consisting of two, small beta-sheets (beta1: B1 and B2; beta2: B3-B5) flanked at the N- and, C-termini by alpha-helices (H1 and H2). Such a fold is very compact in, shape and allows ejection of IPI* through the narrow 30-A portal and tail, tube apertures of the virion without unfolding. Structural and dynamic, measurements identify an exposed hydrophobic knob that is a putative, gmrS/gmrD-binding site. A single gene from the uropathogenic E. coli, UT189, which codes for a gmrS/gmrD-like UT fusion enzyme (with, approximately 90% identity to the heterodimeric CT enzyme), has evolved, IPI* inhibitor immunity. Analysis of the gmrS/gmrD restriction, endonuclease enzyme family and its IPI* family phage antagonists reveals, an evolutionary pathway that has elaborated a surprisingly diverse and, specifically fitted set of coevolving attack and defense structures.
About this Structure
2JUB is a Single protein structure of sequence from Enterobacteria phage tw28. Full crystallographic information is available from OCA.
Reference
Restriction Endonuclease Inhibitor IPI* of Bacteriophage T4: A Novel Structure for a Dedicated Target., Rifat D, Wright NT, Varney KM, Weber DJ, Black LW, J Mol Biol. 2007 Nov 1;. PMID:18037438
Page seeded by OCA on Wed Jan 23 11:12:54 2008
