Yixin Xu, Hugo Muñoz-Hernández, Rościsław Krutyhołowa, Florina Marxer, Ferdane Cetin, Michal Wieczorek
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Partial closure of the γ-tubulin ring complex by CDK5RAP2 activates microtubule nucleation
Microtubule nucleation is templated by the γ-tubulin ring complex (γ-TuRC), but its structure deviates from the geometry of α-/β-tubulin in the microtubule, explaining the complex’s poor nucleating activity. Several proteins may activate the γ-TuRC, but the mechanisms underlying activation are not known. Here, we determined the structure of the porcine γ-TuRC purified using CDK5RAP2’s centrosomin motif 1 (CM1). We identified an unexpected conformation of the γ-TuRC bound to multiple protein modules containing MZT2, GCP2, and CDK5RAP2, resulting in a long-range constriction of the γ-tubulin ring that brings it in closer agreement with the 13-protofilament microtubule. Additional CDK5RAP2 promoted γ-TuRC decoration and stimulated the microtubule-nucleating activities of the porcine γ-TuRC and a reconstituted, CM1-free human complex in single-molecule assays. Our results provide a structural mechanism for the control of microtubule nucleation by CM1 proteins and identify conformational transitions in the γ-TuRC that prime it for microtubule nucleation.
期刊介绍:
Developmental Cell, established in 2001, is a comprehensive journal that explores a wide range of topics in cell and developmental biology. Our publication encompasses work across various disciplines within biology, with a particular emphasis on investigating the intersections between cell biology, developmental biology, and other related fields. Our primary objective is to present research conducted through a cell biological perspective, addressing the essential mechanisms governing cell function, cellular interactions, and responses to the environment. Moreover, we focus on understanding the collective behavior of cells, culminating in the formation of tissues, organs, and whole organisms, while also investigating the consequences of any malfunctions in these intricate processes.