PT  - JOURNAL ARTICLE
AU  - Sidra Aslam
AU  - Xin-Ran Lan
AU  - Deng-Ke Niu
TI  - Aerobiosis Decreases the Genomic GC content in Prokaryotes by Guanine Oxidation
AID  - 10.1101/154534
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 154534
4099  - http://biorxiv.org/content/early/2017/06/23/154534.short
4100  - http://biorxiv.org/content/early/2017/06/23/154534.full
AB  - Oxidative stress is unavoidably faced by oxygen-consuming organisms. Under this stress, guanine is the most fragile base and so most frequently damaged among the four bases. Replication of DNA containing damaged guanines or incorporation of the damaged guanines into DNA strands would cause G to T mutations at a frequency depending on the efficiency of DNA repairing enzymes and the accuracy of replication enzymes. For this reason, aerobiosis is expected to decrease GC content. However, an opposite pattern of base composition in prokaryotes was reported 15 years ago. Although it has been widely cited, its overlook of the effect of shared ancestry determines the necessity to re-examine the reliability of its results. In the present study, by phylogenetically independent comparisons, we found that aerobic prokaryotes have significantly lower whole-genome GC contents than anaerobic ones. When the GC content is measured only at the 4-fold degenerate sites, the difference between aerobic prokaryotes and anaerobic prokaryotes became larger, being consistent with a mutational force imposed by oxidative stress on the evolution of nucleotide composition.