title: Kif2C minimal functional domain has unusual nucleotide binding properties that are adapted to microtubule depolymerization.
abstract: The kinesin-13 Kif2C hydrolyzes ATP and uses the energy released to disassemble microtubules. The mechanism by which this is achieved remains elusive. Here we show that Kif2C-(sN+M), a monomeric construct consisting of the motor domain with the proximal part of the N-terminal Neck extension but devoid of its more distal, unstructured, and highly basic part, has a robust depolymerase activity. When detached from microtubules, the Kif2C-(sN+M) nucleotide-binding site is occupied by ATP at physiological concentrations of adenine nucleotides. As a consequence, Kif2C-(sN+M) starts its interaction with microtubules in that state, which differentiates kinesin-13s from motile kinesins. Moreover, in this ATP-bound conformational state, Kif2C-(sN+M) has a higher affinity for soluble tubulin compared with microtubules. We propose a mechanism in which, in the first step, the specificity of ATP-bound Kif2C for soluble tubulin causes it to stabilize a curved conformation of tubulin heterodimers at the ends of microtubules. Data from an ATPase-deficient Kif2C mutant suggest that, then, ATP hydrolysis precedes and is required for tubulin release to take place. Finally, comparison with Kif2C-Motor indicates that the binding specificity for curved tubulin and, accordingly, the microtubule depolymerase activity are conferred to the motor domain by its N-terminal Neck extension.
authors.affiliation: Institute of Protein Research, Tongji University, Shanghai 200092, China.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Wang
authors.forename: Qiyang
authors.initials: Q
authors.lastname: Jiang
authors.forename: Manuela
authors.initials: M
authors.lastname: Argentini
authors.forename: David
authors.initials: D
authors.lastname: Cornu
authors.forename: Benoît
authors.initials: B
authors.lastname: Gigant
authors.forename: Marcel
authors.initials: M
authors.lastname: Knossow
authors.forename: Chunguang
authors.initials: C
authors.lastname: Wang
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D006801:Humans; D006868:Hydrolysis; D016547:Kinesins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding; D055503:Protein Multimerization; D013552:Swine; D014404:Tubulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C091489:KIF2C protein, human; D014404:Tubulin; D000255:Adenosine Triphosphate; D016547:Kinesins