4efh | pdb_00004efh
Acanthamoeba Actin complex with Spir domain D
Structural highlights
Function[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 PubMedSpire is a WH2 domain-containing actin nucleator essential for establishing an actin mesh during oogenesis. In vitro, in addition to nucleating filaments, Spire can sever them and sequester actin monomers. Understanding how Spire is capable of these disparate functions and which are physiologically relevant is an important goal. To study severing, we examined the effect of Drosophila Spire on preformed filaments in bulk and single filament assays. We observed rapid depolymerization of actin filaments by Spire, which we conclude is largely due to its sequestration activity and enhanced by its weak severing activity. We also studied the solution and crystal structures of Spire-actin complexes. We find structural and functional differences between constructs containing four WH2-domains (Spir-ABCD) and two WH2-domains (Spir-CD) that may provide insight into mechanisms of nucleation and sequestration. Intriguingly, we observed lateral interactions between actin monomers associated with Spir-ABCD, suggesting that the structures built by these four tandem WH2 domains are more complex than originally imagined. Finally, we propose that Spire-actin mixtures contain both nuclei and sequestration structures. Multiple forms of Spire-actin complexes and their functional consequences.,Chen CK, Sawaya MR, Phillips ML, Reisler E, Quinlan ME J Biol Chem. 2012 Feb 8. PMID:22334675[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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