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1nwk
From Proteopedia
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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 , and 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
Page seeded by OCA on Thu Feb 21 14:10:51 2008
