title: Spo5/Mug12, a putative meiosis-specific RNA-binding protein, is essential for meiotic progression and forms Mei2 dot-like nuclear foci.
abstract: We report here a functional analysis of spo5(+)(mug12(+)) of Schizosaccharomyces pombe, which encodes a putative RNA-binding protein. The disruption of spo5(+) caused abnormal sporulation, generating inviable spores due to failed forespore membrane formation and the absence of a spore wall, as determined by electron microscopy. Spo5 regulates the progression of meiosis I because spo5 mutant cells display normal premeiotic DNA synthesis and the timely initiation of meiosis I but they show a delay in the peaking of cells with two nuclei, abnormal tyrosine 15 dephosphorylation of Cdc2, incomplete degradation of Cdc13, retarded formation and repair of double strand breaks, and a reduced frequency of intragenic recombination. Immunostaining showed that Spo5-green fluorescent protein (GFP) appeared in the cytoplasm at the horsetail phase, peaked around the metaphase I to anaphase I transition, and suddenly disappeared after anaphase II. Images of Spo5-GFP in living cells revealed that Spo5 forms a dot in the nucleus at prophase I that colocalized with the Mei2 dot. Unlike the Mei2 dot, however, the Spo5 dot was observed even in sme2Delta cells. Taken together, we conclude that Spo5 is a novel regulator of meiosis I and that it may function in the vicinity of the Mei2 dot.
authors.affiliation: Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kasama
authors.forename: Akira
authors.initials: A
authors.lastname: Shigehisa
authors.forename: Aiko
authors.initials: A
authors.lastname: Hirata
authors.forename: Takamune T
authors.initials: TT
authors.lastname: Saito
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tougan
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okuzaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nojima
mesh_terms: D000595:Amino Acid Sequence; D008540:Meiosis; D008969:Molecular Sequence Data; D009154:Mutation; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013172:Spores, Fungal / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D016601:RNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C516717:Spo5 protein, S pombe; C088896:mei2 protein, S pombe