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From Proteopedia
Crystal Structure of CDC10 - CDC3 heterocomplex from Saccharomyces cerevisiae
Structural highlights
FunctionCDC10_YEAST Septins are GTPases involved in cytokinesis that assemble early in the cell cycle as a patch at the incipient bud site and form a ring approximate 15 minutes before bud emergence, which transforms into an hour-glass shaped collar of cortical filaments that spans both sides of the mother-bud neck. This collar persists until just before cytokinesis, when it splits into two rings that occupy opposite sides of the neck. The septins at the bud neck serve as a structural scaffold that recruits different components involved in diverse processes at specific stages during the cell cycle. Many proteins bind asymmetrically to the septin collar. The septin assembly is regulated by protein kinases GIN4 and/or CLA4. May act by recruiting MYO1 and HOF1, a protein involved in septation, to the site of cleavage. Septins are also involved in cell morphogenesis, bud site selection, chitin deposition, cell cycle regulation, cell compartmentalization and spore wall formation. Publication Abstract from PubMedSeptins, often described as the fourth component of the cytoskeleton, are structural proteins found in a vast variety of living beings. They are related to small GTPases and thus, generally, present GTPase activity which may play an important (although incompletely understood) role in their organization and function. Septins polymerize into long non-polar filaments, in which each subunit interacts with two others by alternating interfaces, NC and G. In Saccharomyces cerevisiae four septins are organized in the following manner, [Cdc11-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11](n) in order to form filaments. Although septins were originally discovered in yeast and much is known regarding their biochemistry and function, only limited structural information about them is currently available. Here we present crystal structures of Cdc3/Cdc10 which provide the first view of the physiological interfaces formed by yeast septins. The G-interface has properties which place it in between that formed by SEPT2/SEPT6 and SEPT7/SEPT3 in human filaments. Switch I from Cdc10 contributes significantly to the interface, whereas in Cdc3 it is largely disorded. However, the significant negative charge density of the latter suggests it may have a unique role. At the NC-interface, we describe an elegant means by which the sidechain of a glutamine from helix alpha(0) imitates a peptide group in order to retain hydrogen-bond continuity at the kink between helices alpha(5) and alpha(6) in the neighbouring subunit, thereby justifying the conservation of the helical distortion. Its absence from Cdc11, along with this structure's other unusual features are critically discussed by comparison with Cdc3 and Cdc10. A key piece of the puzzle: The central tetramer of the Saccharomyces cerevisiae septin protofilament and its implications for self-assembly.,Marques da Silva R, Christe Dos Reis Saladino G, Antonio Leonardo D, D'Muniz Pereira H, Andrea Sculaccio S, Paula Ulian Araujo A, Charles Garratt R J Struct Biol. 2023 Jun 12;215(3):107983. doi: 10.1016/j.jsb.2023.107983. PMID:37315820[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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