Chattopadhyay Sujay, Sahoo Satyabrata, Kanner William A, Chakrabarti Jayprokas
Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700 032, India.
Comp Funct Genomics. 2003;4(1):56-65. doi: 10.1002/cfg.246.
Our studies on the bases of codons from 11 completely sequenced archaeal genomes show that, as we move from GC-rich to AT-rich protein-coding gene-containing species, the differences between G and C and between A and T, the purine load (AG content), and also the overall persistence (i.e. the tendency of a base to be followed by the same base) within codons, all increase almost simultaneously, although the extent of increase is different over the three positions within codons. These findings suggest that the deviations from the second parity rule (through the increasing differences between complementary base contents) and the increasing purine load hinder the chance of formation of the intra-strand Watson-Crick base-paired secondary structures in mRNAs (synonymous with the protein-coding genes we dealt with), thereby increasing the translational efficiency. We hypothesize that the ATrich protein-coding gene-containing archaeal species might have better translational efficiency than their GC-rich counterparts.
我们基于11个已完全测序的古菌基因组密码子的研究表明，当我们从富含GC的含蛋白质编码基因的物种转向富含AT的物种时，密码子内G与C之间、A与T之间的差异、嘌呤负荷（AG含量）以及密码子内的整体持续性（即一个碱基后跟随相同碱基的倾向）几乎同时增加，尽管在密码子的三个位置上增加的程度有所不同。这些发现表明，与第二条互补规则的偏差（通过互补碱基含量差异的增加）和嘌呤负荷的增加阻碍了mRNA（与我们研究的蛋白质编码基因同义）中链内沃森-克里克碱基配对二级结构形成的机会，从而提高了翻译效率。我们推测，含有富含AT的蛋白质编码基因的古菌物种可能比富含GC的对应物种具有更高的翻译效率。
