3mmv
From Proteopedia
Structures of actin-bound WH2 domains of Spire and the implication for filament nucleation
Structural highlights
Function[ACT1_DROME] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. Multiple isoforms are involved in various cellular functions such as cytoskeleton structure, cell mobility, chromosome movement and muscle contraction. [SPIR_DROME] Acts as an actin nucleation factor, remains associated with the slow-growing pointed end of the new filament. Promotes dissociation of capu from the barbed end of actin filaments. Involved in intracellular vesicle transport along actin fibers, providing a novel link between actin cytoskeleton dynamics and intracellular transport. Required for localization of determinants within the developing oocyte to the posterior pole and to the dorsal anterior corner. Links Rho family signaling and Jnk function to the actin cytoskeleton.[1] [2] [3] [4] [5] Publication Abstract from PubMedThree classes of proteins are known to nucleate new filaments: the Arp2/3 complex, formins, and the third group of proteins that contain ca. 25 amino acid long actin-binding Wiskott-Aldrich syndrome protein homology 2 domains, called the WH2 repeats. Crystal structures of the complexes between the actin-binding WH2 repeats of the Spire protein and actin were determined for the Spire single WH2 domain D, the double (SpirCD), triple (SpirBCD), quadruple (SpirABCD) domains, and an artificial Spire WH2 construct comprising three identical D repeats (SpirDDD). SpirCD represents the minimal functional core of Spire that can nucleate actin filaments. Packing in the crystals of the actin complexes with SpirCD, SpirBCD, SpirABCD, and SpirDDD shows the presence of two types of assemblies, "side-to-side" and "straight-longitudinal," which can serve as actin filament nuclei. The principal feature of these structures is their loose, open conformations, in which the sides of actins that normally constitute the inner interface core of a filament are flipped inside out. These Spire structures are distant from those seen in the filamentous nuclei of Arp2/3, formins, and in the F-actin filament. Structures of actin-bound Wiskott-Aldrich syndrome protein homology 2 (WH2) domains of Spire and the implication for filament nucleation.,Ducka AM, Joel P, Popowicz GM, Trybus KM, Schleicher M, Noegel AA, Huber R, Holak TA, Sitar T Proc Natl Acad Sci U S A. 2010 Jun 29;107(26):11757-62. Epub 2010 Jun 10. PMID:20538977[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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