4b1x
Structure of the Phactr1 RPEL-2 bound to G-actinStructure of the Phactr1 RPEL-2 bound to G-actin
Structural highlights
FunctionACTS_RABIT Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. Publication Abstract from PubMedThe 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. Structures of the Phactr1 RPEL Domain and RPEL Motif Complexes with G-Actin Reveal the Molecular Basis for Actin Binding Cooperativity.,Mouilleron S, Wiezlak M, O'Reilly N, Treisman R, McDonald NQ Structure. 2012 Oct 2. pii: S0969-2126(12)00335-8. doi:, 10.1016/j.str.2012.08.031. PMID:23041370[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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