title: Analysis of genomic G + C content, codon usage, initiator codon context and translation termination sites in Tetrahymena thermophila.
abstract: In recent years, the amount of molecular sequencing data from Tetrahymena thermophila has dramatically increased. We analyzed G + C content, codon usage, initiator codon context and stop codon sites in the extremely A + T rich genome of this ciliate. Average G + C content was 38% for protein coding regions, 21% for 5' non-coding sequences, 19% for 3' non-coding sequences, 15% for introns, 19% for micronuclear limited sequences and 17% for macronuclear retained sequences flanking micronuclear specific regions. The 75 available T. thermophila protein coding sequences favored codons ending in T and, where possible, avoided those with G in the third position. Highly expressed genes were relatively G + C-rich and exhibited an extremely biased pattern of codon usage while developmentally regulated genes were more A + T-rich and showed less codon usage bias. Regions immediately preceding Tetrahymena translation initiator codons were generally A-rich. For the 60 stop codons examined, the frequency of G in the end + 1 site was much higher than expected whereas C never occupied this position.
authors.affiliation: Department of Biology, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Wuitschick
authors.forename: K M
authors.initials: KM
authors.lastname: Karrer
mesh_terms: D000818:Animals; D001482:Base Composition / Q000235:genetics*; D003062:Codon / Q000235:genetics*; D018387:Codon, Initiator / Q000235:genetics; D018388:Codon, Terminator / Q000235:genetics; D017125:Genes, Protozoan; D014176:Protein Biosynthesis; D016808:Tetrahymena thermophila / Q000235:genetics*
chemical_list: D003062:Codon; D018387:Codon, Initiator; D018388:Codon, Terminator