Identification of a developmentally regulated septin and involvement of the septins in spore formation in Saccharomyces cerevisiae.
The Saccharomyces cerevisiae CDC3, CDC10, CDC11, and CDC12 genes encode a family of related proteins, the septins, which are involved in cell division and the organization of the cell surface during vegetative growth. A search for additional S. cerevisiae septin genes using the polymerase chain reaction identified SPR3, a gene that had been identified previously on the basis of its sporulation-specific expression. The predicted SPR3 product shows 25-40% identity in amino acid sequence to the previously known septins from S. cerevisiae and other organisms. Immunoblots confirmed the sporulation-specific expression of Spr3p and showed that other septins are also present at substantial levels in sporulating cells. Consistent with the expression data, deletion of SPR3 in either of two genetic backgrounds had no detectable effect on exponentially growing cells. In one genetic background, deletion of SPR3 produced a threefold reduction in sporulation efficiency, although meiosis appeared to be completed normally. In this background, deletion of CDC10 had no detectable effect on sporulation. In the other genetic background tested, the consequences of the two deletions were reversed. Immunofluorescence observations suggest that Spr3p, Cdc3p, and Cdc11p are localized to the leading edges of the membrane sacs that form near the spindle-pole bodies and gradually extend to engulf the nuclear lobes that contain the haploid chromosome sets, thus forming the spores. Deletion of SPR3 does not prevent the localization of Cdc3p and Cdc11p, but these proteins appear to be less well organized, and the intensity of their staining is reduced. Taken together, the results suggest that the septins play important but partially redundant roles during the process of spore formation.
Fares
H
H
Department of Biology, University of North Carolina, Chapel Hill 27599, USA.
Goetsch
L
L
Pringle
J R
JR
D000595:Amino Acid Sequence; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000302:isolation & purification; D002455:Cell Division; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D005656:Fungal Proteins / Q000096:biosynthesis; D020558:GTP Phosphohydrolases; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005838:Genotype; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D051304:Profilins; D011994:Recombinant Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal; D014157:Transcription Factors
C099502:CDC11 protein, S cerevisiae; C099504:CDC12 protein, S cerevisiae; C086662:CDC3 protein, S cerevisiae; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D008565:Membrane Proteins; D051304:Profilins; D011994:Recombinant Proteins; C096553:SPR3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C061178:cdc10 protein, S pombe; C512892:CDC10 protein, S cerevisiae; D020558:GTP Phosphohydrolases