3OKQ

Crystal structure of a core domain of yeast actin nucleation cofactor Bud6

Summary for 3OKQ

• Entry DOI: 10.2210/pdb3okq/pdb
• Related: 3ONX
• Descriptor: Bud site selection protein 6 (2 entities in total)
• Functional Keywords: coiled-coil, protein binding
• Biological source: Saccharomyces cerevisiae (brewer's yeast,lager beer yeast,yeast)
• Total number of polymer chains: 1
• Total formula weight: 16355.49

Authors

Tu, D.,Eck, M.J. (deposition date: 2010-08-25, release date: 2011-09-14, Last modification date: 2023-09-06)

Primary citation

Tu, D.,Graziano, B.R.,Park, E.,Zheng, W.,Li, Y.,Goode, B.L.,Eck, M.J.
Structure of the formin-interaction domain of the actin nucleation-promoting factor Bud6.
Proc.Natl.Acad.Sci.USA, 109:E3424-E3433, 2012

PubMed Abstract: Formin proteins and their associated factors cooperate to assemble unbranched actin filaments in diverse cellular structures. The Saccharomyces cerevisiae formin Bni1 and its associated nucleation-promoting factor (NPF) Bud6 generate actin cables and mediate polarized cell growth. Bud6 binds to both the tail of the formin and G-actin, thereby recruiting monomeric actin to the formin to create a nucleation seed. Here, we structurally and functionally dissect the nucleation-promoting C-terminal region of Bud6 into a Bni1-binding "core" domain and a G-actin binding "flank" domain. The ∼2-Å resolution crystal structure of the Bud6 core domain reveals an elongated dimeric rod with a unique fold resembling a triple-helical coiled-coil. Binding and actin-assembly assays show that conserved residues on the surface of this domain mediate binding to Bni1 and are required for NPF activity. We find that the Bni1 dimer binds two Bud6 dimers and that the Bud6 flank binds a single G-actin molecule. These findings suggest a model in which a Bni1/Bud6 complex with a 2:4 subunit stoichiometry assembles a nucleation seed with Bud6 coordinating up to four actin subunits.

PubMed: 23161908
DOI: 10.1073/pnas.1203035109

Experimental method

X-RAY DIFFRACTION (2.044 Å)