STM1, a gene which encodes a guanine quadruplex binding protein, interacts with CDC13 in Saccharomyces cerevisiae.
The CDC13 gene encodes a protein that binds to the G-rich single-strand at yeast telomeres, and serves as a regulator of telomere replication. Cdc13 interacts with Est1 and DNA polymerase alpha, and cells carrying the temperature-sensitive allele cdc13-1 cannot complete telomere replication at the restrictive temperature and possess long telomeres. We attempted to isolate and characterize genes that interact with CDC13, in order to clarify the molecular mechanisms of telomere replication. A STM1 cDNA was isolated in a two-hybrid screen using CDC13 as a bait. The temperature-sensitive growth phenotype and the alteration in telomere size in cdc13-1 cells were corrected by introduction of the STM1 gene on a multicopy vector, but the extended G-rich single-strand overhangs which are also characteristic in the cdc13-1 mutant were not affected. Furthermore, we found that multiple copies of SGS1, a gene encoding a helicase that can unwind guanine quadruplexes, inhibited suppression of the cdc13-1 phenotype by STM1. We also demonstrate that a fusion protein consisting of the N-terminal region of Cdc13 and the C-terminal region of Stm1 (which shows similarity to the beta-subunit of the telomere binding complex in Oxytricha) could complement a cdc13 disruptant. Although STM1 itself is not essential for telomere replication, our findings suggest that STM1 genetically interacts with CDC13 to maintain telomere structure.
Hayashi
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Department of Molecular Oncology, Cancer Research Institute, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-0934, Japan. naoyuki@kenroku.kanazawa-u.ac.jp
Murakami
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S
D000595:Amino Acid Sequence; D001665:Binding Sites; D004265:DNA Helicases / Q000378:metabolism; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D039642:Eukaryotic Initiation Factors; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors; D011485:Protein Binding; D012316:RNA Nucleotidyltransferases / Q000235:genetics* / Q000378:metabolism; D053484:RecQ Helicases; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D016615:Telomere / Q000235:genetics; D034501:Telomere-Binding Proteins
C452219:Cdc13 protein, S cerevisiae; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D039642:Eukaryotic Initiation Factors; D005656:Fungal Proteins; D010448:Peptide Initiation Factors; D029701:Saccharomyces cerevisiae Proteins; C083432:TIF3 protein, S cerevisiae; D034501:Telomere-Binding Proteins; D012316:RNA Nucleotidyltransferases; C090472:SGS1 protein, S cerevisiae; D004265:DNA Helicases; D053484:RecQ Helicases