title: Cdc13 N-terminal dimerization, DNA binding, and telomere length regulation.
abstract: The essential yeast protein Cdc13 facilitates chromosome end replication by recruiting telomerase to telomeres, and together with its interacting partners Stn1 and Ten1, it protects chromosome ends from nucleolytic attack, thus contributing to genome integrity. Although Cdc13 has been studied extensively, the precise role of its N-terminal domain (Cdc13N) in telomere length regulation remains unclear. Here we present a structural, biochemical, and functional characterization of Cdc13N. The structure reveals that this domain comprises an oligonucleotide/oligosaccharide binding (OB) fold and is involved in Cdc13 dimerization. Biochemical data show that Cdc13N weakly binds long, single-stranded, telomeric DNA in a fashion that is directly dependent on domain oligomerization. When introduced into full-length Cdc13 in vivo, point mutations that prevented Cdc13N dimerization or DNA binding caused telomere shortening or lengthening, respectively. The multiple DNA binding domains and dimeric nature of Cdc13 offer unique insights into how it coordinates the recruitment and regulation of telomerase access to the telomeres.
authors.affiliation: The Wistar Institute, 3601 Spruce St., Philadelphia, PA 19104, USA.
authors.forename: Meghan T
authors.initials: MT
authors.lastname: Mitchell
authors.forename: Jasmine S
authors.initials: JS
authors.lastname: Smith
authors.forename: Mark
authors.initials: M
authors.lastname: Mason
authors.forename: Sandy
authors.initials: S
authors.lastname: Harper
authors.forename: David W
authors.initials: DW
authors.lastname: Speicher
authors.forename: F Brad
authors.initials: FB
authors.lastname: Johnson
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Skordalakes
mesh_terms: D000595:Amino Acid Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: C452219:Cdc13 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D034501:Telomere-Binding Proteins; D004247:DNA