RT Journal Article
SR Electronic
T1 Structural Basis for Katanin Self-Assembly
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 197558
DO 10.1101/197558
A1 Stanley Nithiananatham
A1 Francis J. McNally
A1 Jawdat Al-Bassam
YR 2017
UL http://biorxiv.org/content/early/2017/10/03/197558.abstract
AB The reorganization of microtubules in mitosis, meiosis and development requires the microtubule-severing activity of katanin. Katanin is composed of a AAA ATPase subunit and a regulatory subunit. Microtubule severing requires ATP hydrolysis by katanin’s conserved AAA ATPase domains. Whereas other AAA ATPases form stable hexamers, we show that wild-type katanin only forms heterodimers and heterotetramers. Heterododecamers were only observed for an ATP hydrolysis deficient mutant in the presence of ATP, suggesting an auto-inhibition mechanism that prevents oligomerization. X-ray structures of katanin’s AAA ATPase in monomeric nucleotide-free and pseudo-oligomeric ADP-bound states reveal conformational changes in AAA subdomains and N and C-terminal expansion segments that explain this auto-inhibition of assembly. These data lead to a model in which self-inhibited heterodimers bind to a microtubule, then transition into an assembly-competent conformation upon ATP binding. Microtubule-bound heterododecamers then promote tubulin extraction from the microtubule prior to oligomer dissociation.