4B1Y: Structure of the Phactr1 RPEL-3 bound to G-actin

Citation:
Abstract
The Phactr family of PP1-binding proteins and the myocardin-related transcription factor family of transcriptional coactivators contain regulatory domains comprising three copies of the RPEL motif, a G-actin binding element. We report the structure of a Phactr1 G-actinRPEL domain complex. Three G-actins surround the crank-shaped RPEL domain forming a closed helical assembly. Their spatial relationship is identical to the RPEL-actins within the pentavalent MRTF G-actinRPEL domain complex, suggesting that conserved cooperative interactions between actinRPEL units organize the assembly. In the trivalent Phactr1 complex, each G-actinRPEL unit makes secondary contacts with its downstream actin involving distinct RPEL residues. Similar secondary contacts are seen in G-actinRPEL peptide crystals. Loss-of-secondary-contact mutations destabilize the Phactr1 G-actinRPEL assembly. Furthermore, actin-mediated inhibition of Phactr1 nuclear import requires secondary contact residues in the Phactr1 N-terminal RPEL-N motif, suggesting that it involves interaction of RPEL-N with the C-terminal assembly. Secondary actin contacts by actin-bound RPEL motifs thus govern formation of multivalent actinRPEL assemblies.
PDB ID: 4B1YDownload
MMDB ID: 112171
PDB Deposition Date: 2012/7/12
Updated in MMDB: 2014/11
Experimental Method:
x-ray diffraction
Resolution: 1.29  Å
Source Organism:
Oryctolagus cuniculus
Similar Structures:
Biological Unit for 4B1Y: dimeric; determined by software (PQS)
Molecular Components in 4B1Y
Label Count Molecule
Proteins (2 molecules)
1
Actin, Alpha Skeletal Muscle
Molecule annotation
1
Phosphatase and Actin Regulator 1
Molecule annotation
Chemicals (9 molecules)
1
1
2
1
3
1
4
1
5
1
6
3
7
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.