title: Structure of Tetrahymena telomerase reveals previously unknown subunits, functions, and interactions.
abstract: Telomerase helps maintain telomeres by processive synthesis of telomere repeat DNA at their 3'-ends, using an integral telomerase RNA (TER) and telomerase reverse transcriptase (TERT). We report the cryo-electron microscopy structure of Tetrahymena telomerase at ~9 angstrom resolution. In addition to seven known holoenzyme proteins, we identify two additional proteins that form a complex (TEB) with single-stranded telomere DNA-binding protein Teb1, paralogous to heterotrimeric replication protein A (RPA). The p75-p45-p19 subcomplex is identified as another RPA-related complex, CST (CTC1-STN1-TEN1). This study reveals the paths of TER in the TERT-TER-p65 catalytic core and single-stranded DNA exit; extensive subunit interactions of the TERT essential N-terminal domain, p50, and TEB; and other subunit identities and structures, including p19 and p45C crystal structures. Our findings provide structural and mechanistic insights into telomerase holoenzyme function.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA. Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA. California Nanosystems Institute, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Jiansen
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Chan
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors.forename: Darian D
authors.initials: DD
authors.lastname: Cash
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Miracco
authors.affiliation: Department of Biological Chemistry, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Ogorzalek Loo
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Upton
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA. UCLA-U.S. Department of Energy (DOE) Institute of Genomics and Proteomics, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Duilio
authors.initials: D
authors.lastname: Cascio
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
authors.forename: Reid
authors.initials: R
authors.lastname: O'Brien Johnson
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Collins
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA. Department of Biological Chemistry, UCLA, Los Angeles, CA 90095, USA. UCLA-U.S. Department of Energy (DOE) Institute of Genomics and Proteomics, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Loo
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA. California Nanosystems Institute, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Z Hong
authors.initials: ZH
authors.lastname: Zhou
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA. California Nanosystems Institute, UCLA, Los Angeles, CA 90095, USA. UCLA-U.S. Department of Energy (DOE) Institute of Genomics and Proteomics, UCLA, Los Angeles, CA 90095, USA. feigon@mbi.ucla.edu.
authors.forename: Juli
authors.initials: J
authors.lastname: Feigon
mesh_terms: D020134:Catalytic Domain; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D004277:DNA, Single-Stranded / Q000737:chemistry; D020035:Holoenzymes / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry; D012313:RNA / Q000737:chemistry*; D051716:Replication Protein A / Q000737:chemistry; D019098:Telomerase / Q000737:chemistry*; D016615:Telomere / Q000737:chemistry; D059505:Telomere Homeostasis; D034501:Telomere-Binding Proteins; D013768:Tetrahymena / Q000201:enzymology*
chemical_list: D004277:DNA, Single-Stranded; D020035:Holoenzymes; D021122:Protein Subunits; D051716:Replication Protein A; D034501:Telomere-Binding Proteins; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase