1NWK: CRYSTAL STRUCTURE OF MONOMERIC ACTIN IN THE ATP STATE

Citation:
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.
PDB ID: 1NWKDownload
MMDB ID: 50538
PDB Deposition Date: 2003/2/6
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.85  Å
Source Organism:
Similar Structures:
Biological Unit for 1NWK: monomeric; determined by author
Molecular Components in 1NWK
Label Count Molecule
Protein (1 molecule)
1
Actin, Alpha Skeletal Muscle
Molecule annotation
Chemicals (6 molecules)
1
4
2
1
3
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.