title: Functions of sensor 1 and sensor 2 regions of Saccharomyces cerevisiae Cdc6p in vivo and in vitro.
abstract: Cdc6p is a key regulator of the cell cycle in eukaryotes and is a member of the AAA(+) (ATPases associated with a variety of cellular activities) family of proteins. In this family of proteins, the sensor 1 and sensor 2 regions are important for their function and ATPase activity. Here, site-directed mutagenesis has been used to examine the role of these regions of Saccharomyces cerevisiae Cdc6p in controlling the cell cycle progression and initiation of DNA replication. Two important amino acid residues (Asn(263) in sensor 1 and Arg(332) in sensor 2) were identified as key residues for Cdc6p function in vivo. Cells expressing mutant Cdc6p (N263A or R332E) grew slowly and accumulated in the S phase. In cells expressing mutant Cdc6p, loading of the minichromosome maintenance (MCM) complex of proteins was decreased, suggesting that the slow progression of S phase in these cells was due to inefficient MCM loading on chromatin. Purified wild type Cdc6p but not mutant Cdc6p (N263A and R332E) caused the structural modification of origin recognition complex proteins. These results are consistent with the idea that Cdc6p uses its ATPase activity to change the conformation of origin recognition complex, and then together they recruit the MCM complex.
authors.affiliation: Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Takahashi
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsutsumi
authors.forename: Tomofusa
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Bruce
authors.initials: B
authors.lastname: Stillman
authors.forename: Tohru
authors.initials: T
authors.lastname: Mizushima
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001120:Arginine; D001216:Asparagine; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D005838:Genotype; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
chemical_list: C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002843:Chromatin; D005656:Fungal Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D001216:Asparagine; D001120:Arginine