Structural basis for telomerase catalytic subunit TERT binding to RNA template and telomeric DNA

• Published in: Nature structural & molecular biology Vol. 17; no. 4; pp. 513 - 518
• Main Authors: Futahashi, Mizuko, Fujiwara, Haruhiko, Skordalakes, Emmanuel, Gillis, Andrew, Mitchell, Meghan
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.04.2010; Nature Publishing Group
• Subjects: 631/45/535; Animals; BASIC BIOLOGICAL SCIENCES; Binding sites; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; Catalysis; Catalytic Domain; Chemical properties; CHROMOSOMES; CONFORMATIONAL CHANGES; CRYSTAL STRUCTURE; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA POLYMERASES; DNA REPLICATION; ENZYMES; Flour beetles; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; Genetic aspects; Life Sciences; Membrane Biology; Models, Molecular; national synchrotron light source; NUCLEIC ACIDS; NUCLEOTIDES; Physiological aspects; Protein Conformation; Protein Structure; Ribonucleic acid; Ribonucleoproteins; RNA; RNA - metabolism; Solvents; STABILITY; Structure; Telomerase; Telomerase - metabolism; Telomere; Templates, Genetic; TRIBOLIUM; Tribolium - enzymology; Tribolium castaneum; VIABILITY; Japan
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb.1777

The crystal structure of the beetle Tribolium castaneum telomerase catalytic subunit (TERT) bound to a short RNA-DNA hybrid that represents the putative RNA template and the telomeric DNA is now presented, revealing the specific contacts between TERT and nucleic acid template and product. Telomerase is a specialized DNA polymerase that extends the 3′ ends of eukaryotic linear chromosomes, a process required for genomic stability and cell viability. Here we present the crystal structure of the active Tribolium castaneum telomerase catalytic subunit, TERT, bound to an RNA-DNA hairpin designed to resemble the putative RNA-templating region and telomeric DNA. The RNA-DNA hybrid adopts a helical structure, docked in the interior cavity of the TERT ring. Contacts between the RNA template and motifs 2 and B′ position the solvent-accessible RNA bases close to the enzyme active site for nucleotide binding and selectivity. Nucleic acid binding induces rigid TERT conformational changes to form a tight catalytic complex. Overall, TERT–RNA template and TERT–telomeric DNA associations are remarkably similar to those observed for retroviral reverse transcriptases, suggesting common mechanistic aspects of DNA replication between the two families of enzymes.