Download MendeleyCrystal structure of monomeric actin in the ATP state. Structural basis of nucleotide-dependent actin dynamics.
Graceffa, P., Dominguez, R.(2003) J Biol Chem 278: 34172-34180
- PubMed: 12813032
- DOI: https://doi.org/10.1074/jbc.M303689200
- Primary Citation of Related Structures:
1NWK - PubMed Abstract:
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.
Organizational Affiliation:
Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
