1y64
From Proteopedia
Bni1p Formin Homology 2 Domain complexed with ATP-actin
Structural highlights
Function[ACTS_RABIT] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. [BNI1_YEAST] Required for the assembly of F-actin structures, such as actin cables and stress fibers. Nucleates actin filaments. Binds to the barbed end of the actin filament and acts as leaky capper, slowing both polymerization and depolymerization. Protects the growing actin fiber from tight capping proteins and so increases the time of elongation and the total amount of F-actin. May organize microtubules by mediating spindle positioning and movement in the budding process. Potential target of the RHO family members.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe conserved formin homology 2 (FH2) domain nucleates actin filaments and remains bound to the barbed end of the growing filament. Here we report the crystal structure of the yeast Bni1p FH2 domain in complex with tetramethylrhodamine-actin. Each of the two structural units in the FH2 dimer binds two actins in an orientation similar to that in an actin filament, suggesting that this structure could function as a filament nucleus. Biochemical properties of heterodimeric FH2 mutants suggest that the wild-type protein equilibrates between two bound states at the barbed end: one permitting monomer binding and the other permitting monomer dissociation. Interconversion between these states allows processive barbed-end polymerization and depolymerization in the presence of bound FH2 domain. Kinetic and/or thermodynamic differences in the conformational and binding equilibria can explain the variable activity of different FH2 domains as well as the effects of the actin-binding protein profilin on FH2 function. Structural basis of actin filament nucleation and processive capping by a formin homology 2 domain.,Otomo T, Tomchick DR, Otomo C, Panchal SC, Machius M, Rosen MK Nature. 2005 Feb 3;433(7025):488-94. Epub 2005 Jan 5. PMID:15635372[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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