Mid2p stabilizes septin rings during cytokinesis in fission yeast

Ana Berlin, Anne Paoletti, Fred Chang

Research output: Contribution to journalArticlepeer-review

118 Scopus citations


Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell-cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and Candida albicans Int1p. Like septin mutants, mid2Δ mutants had delays in cell-cell separation. mid2Δ mutants were defective in septin organization but not contractile ring closure or septum formation. In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract. In mid2Δ cells, septins initially assembled in a single ring but during septation appeared in the cleavage furrow, forming a washer or disc structure. FRAP studies showed that septins are stable in wild-type cells but exchange 30-fold more rapidly in mid2Δ cells. Mid2p colocalized with septins and required septins for its localization. A COOH-terminal pleckstrin homology domain of Mid2p was required for its localization and function. No genetic interactions were found between mid2 and the related gene mid1. Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

Original languageEnglish (US)
Pages (from-to)1083-1092
Number of pages10
JournalJournal of Cell Biology
Issue number7
StatePublished - Apr 3 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cell Biology


  • Contractile ring
  • Cytokinesis
  • FRAP
  • Fission yeast Schizosaccharomyces pombe
  • Septin


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