Spo5/Mug12, a putative meiosis-specific RNA-binding protein, is essential for meiotic progression and forms Mei2 dot-like nuclear foci

Eukaryot Cell. 2006 Aug;5(8):1301-13. doi: 10.1128/EC.00099-06.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Meiosis*
  • Molecular Sequence Data
  • Mutation
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Sequence Alignment
  • Spores, Fungal / metabolism
  • Spores, Fungal / ultrastructure


  • RNA-Binding Proteins
  • Schizosaccharomyces pombe Proteins
  • Spo5 protein, S pombe
  • mei2 protein, S pombe