Ref ID : 7480
Jeffrey D. Wuitschick and Kathleen M. Karrer; Analysis of Genomic G+C Content, Codon Usage, Initiator Codon Context and Translation Termination Sites in Tetrahymena thermophila. J.Eukaryot.Microbiol. 46(3):239-247, 1999
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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 macronucler 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.