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Mol Biol Cell 2011 May 01;229:1550-60. doi: 10.1091/mbc.E10-12-0951.
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The spindle assembly function of Caenorhabditis elegans katanin does not require microtubule-severing activity.

McNally KP , McNally FJ .

Katanin is a heterodimeric microtubule-severing protein that is conserved among eukaryotes. Loss-of-function mutations in the Caenorhabditis elegans katanin catalytic subunit, MEI-1, cause specific defects in female meiotic spindles. To determine the relationship between katanin's microtubule-severing activity and its role in meiotic spindle formation, we analyzed the MEI-1(A338S) mutant. Unlike wild-type MEI-1, which mediated disassembly of microtubule arrays in Xenopus fibroblasts, MEI-1(A338S) had no effect on fibroblast microtubules, indicating a lack of microtubule-severing activity. In C. elegans, MEI-1(A338S) mediated assembly of extremely long bipolar meiotic spindles. In contrast, a nonsense mutation in MEI-1 caused assembly of meiotic spindles without any poles as assayed by localization of the spindle-pole protein, ASPM-1. These results indicated that katanin protein, but not katanin's microtubule-severing activity, is required for assembly of acentriolar meiotic spindle poles. To understand the nonsevering activities of katanin, we characterized the N-terminal domain of the katanin catalytic subunit. The N-terminal domain was necessary and sufficient for binding to the katanin regulatory subunit. The katanin regulatory subunit in turn caused a dramatic change in the microtubule-binding properties of the N-terminal domain of the catalytic subunit. This unique bipartite microtubule-binding structure may mediate the spindle-pole assembly activity of katanin during female meiosis.

PubMed ID: 21372175
PMC ID: PMC3084677
Article link: Mol Biol Cell
Grant support: [+]

Species referenced: Xenopus
Genes referenced: aspm bltp2 katna1 katnal1 katnb1 mbp tbx2

Article Images: [+] show captions
References [+] :
Babst, The Vps4p AAA ATPase regulates membrane association of a Vps protein complex required for normal endosome function. 1998, Pubmed