Mouilleron, S. and Wiezlak, M. and O’Reilly, N. and Treisman, R. and McDonald, Neil Q. (2012) Structures of the Phactr1 RPEL domain and RPEL motif complexes with G-Actin reveal the molecular basis for Actin Binding Cooperativity. Structure 20 (11), pp. 1960-1970. ISSN 0969-2126.Full text not available from this repository.
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-actin⋅RPEL 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-actin⋅RPEL domain complex, suggesting that conserved cooperative interactions between actin⋅RPEL units organize the assembly. In the trivalent Phactr1 complex, each G-actin⋅RPEL unit makes secondary contacts with its downstream actin involving distinct RPEL residues. Similar secondary contacts are seen in G-actin⋅RPEL peptide crystals. Loss-of-secondary-contact mutations destabilize the Phactr1 G-actin⋅RPEL 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 actin⋅RPEL assemblies.
|School or Research Centre:||Birkbeck Schools and Research Centres > School of Science > Biological Sciences|
|Date Deposited:||18 Oct 2012 11:22|
|Last Modified:||08 May 2013 08:54|
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