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XB-ART-53702
J Biol Chem 2016 Sep 23;29139:20283-20294. doi: 10.1074/jbc.M116.730697.
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The Kinesin-5 Chemomechanical Cycle Is Dominated by a Two-heads-bound State.

Chen GY , Mickolajczyk KJ , Hancock WO .


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Single-molecule microscopy and stopped-flow kinetics assays were carried out to understand the microtubule polymerase activity of kinesin-5 (Eg5). Four lines of evidence argue that the motor primarily resides in a two-heads-bound (2HB) state. First, upon microtubule binding, dimeric Eg5 releases both bound ADPs. Second, microtubule dissociation in saturating ADP is 20-fold slower for the dimer than for the monomer. Third, ATP-triggered mant-ADP release is 5-fold faster than the stepping rate. Fourth, ATP binding is relatively fast when the motor is locked in a 2HB state. Shortening the neck-linker does not facilitate rear-head detachment, suggesting a minimal role for rear-head-gating. This 2HB state may enable Eg5 to stabilize incoming tubulin at the growing microtubule plus-end. The finding that slowly hydrolyzable ATP analogs trigger slower nucleotide release than ATP suggests that ATP hydrolysis in the bound head precedes stepping by the tethered head, leading to a mechanochemical cycle in which processivity is determined by the race between unbinding of the bound head and attachment of the tethered head.

???displayArticle.pubmedLink??? 27402829
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Species referenced: Xenopus laevis
Genes referenced: cyp26a1 kif11 kif5a kif5b kif5c

References [+] :
Andreasson, Examining kinesin processivity within a general gating framework. 2015, Pubmed