1yg8
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(New page: 200px<br /><applet load="1yg8" size="450" color="white" frame="true" align="right" spinBox="true" caption="1yg8, resolution 2.6Å" /> '''The structure of a V6...)
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Revision as of 04:37, 21 November 2007
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The structure of a V6A variant of ClpP.
Overview
ClpP is a self-compartmentalized proteolytic assembly comprised of two, stacked, heptameric rings that, when associated with its cognate hexameric, ATPase (ClpA or ClpX), form the ClpAP and ClpXP ATP-dependent protease, respectively. The symmetry mismatch is an absolute feature of this large, energy-dependent protease and also of the proteasome, which shares a, similar barrel-shaped architecture, but how it is accommodated within the, complex has yet to be understood, despite recent structural, investigations, due in part to the conformational lability of the, N-termini. We present the structures of Escherichia coli ClpP to 1.9A and, an inactive variant that provide some clues for how this might be, achieved. In the wild type protein, the highly conserved N-terminal 20, residues can be grouped into two major structural classes. In the first, a, loop formed by residues 10-15 protrudes out of the central access channel, extending approximately 12-15A from the surface of the oligomer resulting, in the closing of the access channel observed in one ring. Similar loops, are implied to be exclusively observed in human ClpP and a variant of ClpP, from Streptococcus pneumoniae. In the other ring, a second class of loop, is visible in the structure of wt ClpP from E. coli that forms closer to, residue 16 and faces toward the interior of the molecule creating an open, conformation of the access channel. In both classes, residues 18-20, provide a conserved interaction surface. In the inactive variant, a third, class of N-terminal conformation is observed, which arises from a, conformational change in the position of F17. We have performed a detailed, functional analysis on each of the first 20 amino acid residues of ClpP., Residues that extend beyond the plane of the molecule (10-15) have a, lesser effect on ATPase interaction than those lining the pore (1-7 and, 16-20). Based upon our structure-function analysis, we present a model to, explain the widely disparate effects of individual residues on ClpP-ATPase, complex formation and also a possible functional reason for this mismatch.
About this Structure
1YG8 is a Single protein structure of sequence from Escherichia coli. Active as Endopeptidase Clp, with EC number 3.4.21.92 Full crystallographic information is available from OCA.
Reference
The asymmetry in the mature amino-terminus of ClpP facilitates a local symmetry match in ClpAP and ClpXP complexes., Bewley MC, Graziano V, Griffin K, Flanagan JM, J Struct Biol. 2006 Feb;153(2):113-28. Epub 2005 Dec 1. PMID:16406682
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