title: Three TERT genes in Nicotiana tabacum.
abstract: Telomerase is essential for proper functioning of telomeres in eukaryotes. We cloned and characterised genes for the protein subunit of telomerase (TERT) in the allotetraploid Nicotiana tabacum (tobacco) and its diploid progenitor species Nicotiana sylvestris and Nicotiana tomentosiformis with the aim of determining if allopolyploidy (hybridisation and genome duplication) influences TERT activity and divergence. Two of the three sequence variants present in the tobacco genome (NtTERT-C/s and NtTERT-D) revealed similarity to two sequence variants found in N. sylvestris and another variant (NtTERT-C/t) was similar to TERT of N. tomentosiformis. Variants of N. sylvestris origin showed less similarity to each other (80.5 % in the genomic region; 90.1 % in the coding sequence) than that between the NtTERT-C/s and NtTERT-C/t variants (93.6 and 97.2 %, respectively). The NtTERT-D variant was truncated at the 5' end, and indels indicated that it was a pseudogene. All tobacco variants were transcribed and alternatively spliced sequences were detected. Analysis of gene arrangements uncovered a novel exon in the N-terminal domain of TERT variants, a feature that is likely to be commonly found in Solanaceae species. In addition, species-specific duplications were observed within exon 5. The putative function, copy number and evolutionary origin of these NtTERT sequence variants are discussed.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic. evin@ibp.cz
authors.forename: Eva
authors.initials: E
authors.lastname: Sýkorová
authors.forename: Jana
authors.initials: J
authors.lastname: Fulnečková
authors.forename: Petr
authors.initials: P
authors.lastname: Mokroš
authors.forename: Jiří
authors.initials: J
authors.lastname: Fajkus
authors.forename: Miloslava
authors.initials: M
authors.lastname: Fojtová
authors.forename: Vratislav
authors.initials: V
authors.lastname: Peška
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D019143:Evolution, Molecular; D005091:Exons; D023061:Gene Order; D015321:Gene Rearrangement; D056426:Genetic Loci; D018745:Genome, Plant; D007438:Introns; D008969:Molecular Sequence Data; D011544:Pseudogenes; D059368:RNA Isoforms; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D019098:Telomerase / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D059368:RNA Isoforms; D019098:Telomerase