Catalytic subunit of a complex which severs microtubules in an ATP-dependent manner (PubMed:28783150). Microtubule severing may promote rapid reorganization of cellular microtubule arrays. Required specifically for meiotic spindle formation in the female germline; the presence of this protein is inimical to the formation of mitotic spindles (PubMed:8027178, PubMed:10809666, PubMed:12885567, PubMed:19087961, PubMed:23918937). In body wall muscles, regulates organization of myosin thick filaments (PubMed:22621901). n ATP + n H2O + a microtubule = n ADP + n phosphate + (n+1) alpha/beta tubulin heterodimers. ATPase activity is stimulated by microtubules, which promote homooligomerization. ATP-dependent microtubule severing is stimulated by interaction with mei-2. Homohexamer; ATP hydrolysis initiates a cycle between an open spiral and a closed ring conformation which is probably involved in pulling tubulin dimers out from microtubules (PubMed:28783150). Interacts with mei-2, which may serve as a targeting subunit (PubMed:10809666). Interacts with mel-26, which targets mei-1 for ubiquitin mediated proteolysis (PubMed:13679921, PubMed:14528312, PubMed:23918937). Interacts with phosphatase pph-4.1 (PubMed:19087961). Localizes to the spindle poles and condensed chromatin during female meiosis (PubMed:10809666, PubMed:12781129, PubMed:8027178, PubMed:16338136). This localization requires mei-2 (PubMed:10809666). Also localizes to the polar body (PubMed:12781129). Ser-92 phosphorylated mei-1 is first detected on the maternal chromatin in anaphase of meiosis I, then localizes to the cytoplasm during meiosis II and quickly disappears between pronuclear formation and the first cell division, except in the polar bodies (PubMed:16338136). Highly expressed in the female germline. Degradation at the meiosis-mitosis transition reduces cytoplasmic microtubule severing activity, thereby allowing the formation of larger mitotic spindles. Phosphorylated (PubMed:16338136, PubMed:23918937). Phosphorylation by mbk-2 is required for its rapid degradation following meiosis II (PubMed:16338136). Likely dephosphorylated by the PP4 complex composed of catalytic subunit pph-4.1 and regulatory subunit ppfr-1 (PubMed:23918937). Polyubiquitination targets the protein for rapid degradation via the ubiquitin system at the end of meiosis. The BTB domain protein mel-26 may serve to specifically target mei-1 for ubiquitination by cul-3 containing complexes. The cul-3 protein is in turn regulated by neddylation by ned-8. RNAi-mediated knockdown at the L1 larval stage results in the disorganization of myosin thick filaments in adult body wall muscles characterized by the formation of abnormal myosin heavy chain myo-3 aggregates and V-shaped crossing of A-bands. In addition, body wall muscle cells appear shorter and broader. Belongs to the AAA ATPase family. Katanin p60 subunit A1 subfamily.