1nwk
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(New page: 200px<br /><applet load="1nwk" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nwk, resolution 1.85Å" /> '''CRYSTAL STRUCTURE OF...)
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Revision as of 20:29, 20 November 2007
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CRYSTAL STRUCTURE OF MONOMERIC ACTIN IN THE ATP STATE
Overview
A nucleotide-dependent conformational change regulates actin filament, dynamics. Yet, the structural basis of this mechanism remains, controversial. The x-ray crystal structure of, tetramethylrhodamine-5-maleimide-actin with bound AMPPNP, a, non-hydrolyzable ATP analog, was determined to 1.85-A resolution. A, comparison of this structure to that of, tetramethylrhodamine-5-maleimide-actin with bound ADP, determined, previously under similar conditions, reveals how the release of the, nucleotide gamma-phosphate sets in motion a sequence of events leading to, a conformational change in subdomain 2. The side chain of Ser-14 in the, catalytic site rotates upon Pi release, triggering the rearrangement of, the loop containing the methylated His-73, referred to as the sensor loop., This in turn causes a transition in the DNase I-binding loop in subdomain, 2 from a disordered loop in ATP-actin to an ordered alpha-helix in, ADP-actin. Despite this conformational change, the nucleotide cleft, remains closed in ADP-actin, similar to ATP-actin. An analysis of the, existing structures of members of the actin superfamily suggests that the, cleft is open in the nucleotide-free state.
About this Structure
1NWK is a Single protein structure of sequence from Oryctolagus cuniculus with CA, ANP and RHO as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structure of monomeric actin in the ATP state. Structural basis of nucleotide-dependent actin dynamics., Graceffa P, Dominguez R, J Biol Chem. 2003 Sep 5;278(36):34172-80. Epub 2003 Jun 17. PMID:12813032
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