Genomic adaptation of prokaryotic organisms at high temperature.
Genomic adaptation of prokaryotic organisms at high temperature.
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DOI：
10.6026/97320630004352
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发表时间：
2010-02-28
期刊：
影响因子：
1.9
通讯作者：
Ghosh TC
中科院分区：
文献类型：
--
作者：
Basak S;Mukhopadhyay P;Gupta SK;Ghosh TC
研究微生物在高温下稳定核酸分子的适应策略是进化基因组学研究的核心问题之一。如果种间鸟嘌呤和胞嘧啶含量存在较大差异，则热适应假说认为G+C含量与生长温度之间存在联系。然而，关于基因组GC含量与最佳生长温度（Topt）之间的相关性一直存在争议。我们认为，适应高温生长需要一组协调的进化变化，影响：(i)核酸热稳定性和（ii）密码子-反密码子相互作用的稳定性。此外，在杆菌科中，我们已经证明了较高的基因组GC水平对高温下稳定mRNA二级结构没有任何作用。通过对嗜热嗜热热球菌和嗜热耐辐射球菌同源序列的比较分析发现，嗜热热球菌基因链结构对应的编码序列中GC含量的增加对mRNA二级结构具有稳定作用，而非周期结构对应的编码序列中GC含量的增加对mRNA二级结构具有不稳定作用。在此基础上，进一步提出对热适应假说的批判性评述。
One of the central issues of evolutionary genomics is to find out the adaptive strategies of microorganisms to stabilize nucleic acid molecules under high temperature. Thermal adaptation hypothesis gives a link between G+C content and growth temperature if there is a considerable variation of guanine and cytosine content between species. However, there has been a long-standing debate regarding the correlations between genomic GC content and optimal growth temperature (Topt). We urged that adaptation to growth at high temperature requires a coordinated set of evolutionary changes affecting: (i) nucleic acid thermostability and (ii) stability of codon-anticodon interactions. Moreover, in Bacillaceae family we have demonstrated that a higher genomic GC level do not have any role in stabilizing mRNA secondary structure at high growth temperature. Comparative analysis between homologous sequences of thermophilic Thermus thermophilus and mesophilic Deinococcus radiodurans suggests that increased levels of GC contents in the coding sequence corresponding to strand structure of Thermus thermophilus genes have stabilizing effect on the mRNA secondary structure, whereas increased levels of GC contents in coding sequences corresponding to aperiodic structure have destabilizing effect on the mRNA secondary structure. In this perspective, a critical review of thermal adaptation hypothesis is further advocated.