title: Structure of Est3 reveals a bimodal surface with differential roles in telomere replication.
abstract: Telomerase is essential for continuous cellular proliferation. Substantial insights have come from studies of budding yeast telomerase, which consists of a catalytic core in association with two regulatory proteins, ever shorter telomeres 1 and 3 (Est1 and Est3). We report here a high-resolution structure of the Est3 telomerase subunit determined using a recently developed strategy that combines minimal NMR experimental data with Rosetta de novo structure prediction algorithms. Est3 adopts an overall protein fold which is structurally similar to that adopted by the shelterin component TPP1. However, the characteristics of the surface of the experimentally determined Est3 structure are substantially different from those predicted by prior homology-based models of Est3. Structure-guided mutagenesis of the complete surface of the Est3 protein reveals two adjacent patches on a noncanonical face of the protein that differentially mediate telomere function. Mapping these two patches on the Est3 structure defines a set of shared features between Est3 and HsTPP1, suggesting an analogous multifunctional surface on TPP1.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80309-0596.
authors.forename: Timsi
authors.initials: T
authors.lastname: Rao
authors.forename: Johnathan W
authors.initials: JW
authors.lastname: Lubin
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Armstrong
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Tucey
authors.forename: Victoria
authors.initials: V
authors.lastname: Lundblad
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Wuttke
mesh_terms: D000465:Algorithms; D020134:Catalytic Domain; D049109:Cell Proliferation; D003001:Cloning, Molecular; D016000:Cluster Analysis; D004261:DNA Replication; D005816:Genetic Complementation Test; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D016296:Mutagenesis; D020125:Mutation, Missense; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics*; D057057:Serine Proteases / Q000737:chemistry; D000089804:Shelterin Complex; D019098:Telomerase / Q000737:chemistry* / Q000235:genetics*; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins
chemical_list: C495876:ACD protein, human; D029701:Saccharomyces cerevisiae Proteins; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; C491580:EST3 protein, S cerevisiae; D019098:Telomerase; D057057:Serine Proteases
keywords: OB-fold protein; RASREC Rosetta