The Spg1p GTPase is an essential, dosage-dependent inducer of septum formation in Schizosaccharomyces pombe

• Published in: Genes & development Vol. 11; no. 12; pp. 1519 - 1534
• Main Authors: Schmidt, S, Sohrmann, M, Hofmann, K, Woollard, A, Simanis, V
• Format: Journal Article
• Language: English
• Published: United States 15-06-1997
• Subjects: Amino Acid Sequence; Cell Cycle; Cell Cycle Proteins; Cell Division; Gene Expression Regulation, Fungal; Genes, Fungal; Genotype; GTP Phosphohydrolases - blood; GTP Phosphohydrolases - chemistry; GTP Phosphohydrolases - metabolism; Mitosis; Molecular Sequence Data; Mutagenesis, Site-Directed; Phosphoproteins - metabolism; Phylogeny; Point Mutation; Protein Kinases - biosynthesis; Protein-Serine-Threonine Kinases; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Restriction Mapping; Schizosaccharomyces - cytology; Schizosaccharomyces - genetics; Schizosaccharomyces - physiology; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - blood; Schizosaccharomyces pombe Proteins - chemistry; Schizosaccharomyces pombe Proteins - metabolism; Sequence Alignment
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.11.12.1519

The spg1 gene (septum-promoting GTPase) was cloned as a multicopy suppressor of a dominant-negative mutant of the Cdc7p kinase. It encodes a small GTPase of the Ras superfamily. spg1 is an essential gene. Null or heat-sensitive alleles do not make a division septum, but growth, S-phase, and mitosis continue in the absence of cell division, producing elongated, multinucleate cells. Increased expression of Spg1p induces septum formation in G2, S-phase, and pre-Start G1-arrested cells. This requires the activity of Cdc7p kinase, but not p34(cdc2). Increased expression of Cdc7p bypasses the requirement for Spg1p. Spg1p and Cdc7p can be coimmunoprecipitated from cell extracts, and interact in the two-hybrid system. These data indicate that Spg1p is a key element in controlling the onset of septum formation in Schizosaccharomyces pombe, and that it acts through the Cdc7p kinase.