The Caenorhabditis elegans microtubule-severing complex MEI-1/MEI-2 katanin interacts differently with two superficially redundant beta-tubulin isotypes.
The microtubule-severing protein complex katanin is required for a variety of important microtubule-base morphological changes in both animals and plants. Caenorhabditis elegans katanin is encoded by the mei-1 and mei-2 genes and is required for oocyte meiotic spindle formation and must be inactivated before the first mitotic cleavage. We identified a mutation, sb26, in the tbb-2 beta-tubulin gene that partially inhibits MEI-1/MEI-2 activity: sb26 rescues lethality caused by ectopic MEI-1/MEI-2 expression during mitosis, and sb26 increases meiotic defects in a genetic background where MEI-1/MEI-2 activity is lower than normal. sb26 does not interfere with MEI-1/MEI-2 microtubule localization, suggesting that this mutation likely interferes with severing. Tubulin deletion alleles and RNA-mediated interference revealed that TBB-2 and the other germline enriched beta-tubulin isotype, TBB-1, are redundant for embryonic viability. However, limiting MEI-1/MEI-2 activity in these experiments revealed that MEI-1/MEI-2 preferentially interacts with TBB-2-containing microtubules. Our results demonstrate that these two superficially redundant beta-tubulin isotypes have functionally distinct roles in vivo.
Lu
Chenggang
C
Genes and Development Research Group, University of Calgary, Calgary, Alberta, T2N 4N1 Canada.
Srayko
Martin
M
Mains
Paul E
PE
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D000074201:Katanin; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D020033:Protein Isoforms / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D014404:Tubulin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D014404:Tubulin; D000251:Adenosine Triphosphatases; C086678:MEI-1 protein, C elegans; C409220:MEI-2 protein, C elegans; D000074201:Katanin