Prokaryotes that grow optimally in acid have purine-poor codons in long open reading frames |
| |
Authors: | Feng-Hsu Lin Donald R. Forsdyke |
| |
Affiliation: | (1) Department of Biochemistry, Queen’s University, K7L3N6 Kingston, ON, Canada |
| |
Abstract: | In nucleic acids the N-glycosyl bonds between purines and their ribose sugar moities are broken under acid conditions. If one strand of a duplex DNA segment were more vulnerable to mutation than the other, then the archaeon Picrophilus torridus, with an optimum growth pH near zero, could have adapted by decreasing the purine content of that strand. Yet, P. torridus has an optimum growth temperature near 60°C, and thermophiles prefer purine-rich codons. We found that, as in other thermophiles, high growth temperature correlates with the use of purine-rich codons. The extra purines are often in third, non-amino acid determining, codon positions. However, as in other acidophiles, as open reading frame lengths increase, there is increased use of purine-poor codons, particularly those without purines in second, amino acid-determining, codon positions. Thus, P. torridus can be seen as adapting (a) to temperature by increasing its purines in all open reading frames without greatly impacting protein amino acid compositions, and (b) to pH by decreasing purines in longer open reading frames, thereby potentially impacting protein amino acid compositions. It is proposed that longer open reading frames, being larger mutational targets, have become less vulnerable to depurination by virtue of pyrimidine for purine substitutions. |
| |
Keywords: | Acid environment Base composition Codons Extremophiles Optimum growth Purine-loading |
本文献已被 PubMed SpringerLink 等数据库收录! |
|