Bioinformatics Centre, Bose Institute P 1/12, C.I.T. Scheme VII M - Kolkata 700054- India.
J Biomol Struct Dyn. 2010 Feb;27(4):477-88. doi: 10.1080/07391102.2010.10507332.
In human, highly expressed genes contain shorter and fewer introns and these have been attributed to selection for economy in transcription and translation. On the other hand, in plants, it has been shown that highly expressed genes tend to be longer than lowly expressed genes. Here, in this study, we analyzed compositional influence on genome organization in both rice and human. We demonstrated that, in GC rich rice genes, highly expressed genes are less compact than lowly expressed genes. In GC-poor class, there is no difference in gene compactness between highly and lowly expressed genes. However, the scenario is different for human as there is no influence of GC composition on gene compactness due to their expression levels. We also reported that, highly expressed rice GC-rich pre-mRNA tend to form less stable secondary structure than that of lowly expressed genes. However, on removing intronic sequences, highly expressed mRNA form a stable secondary structure as compared to lowly expressed GC-rich genes. We suggest that in GC-rich rice genes long introns are under selection for enhancing transcriptional efficiency by modulating pre-mRNA secondary structural stability. Thus evolutionary mechanisms behind genome organization are different between these two genomes (human and rice).
在人类中，高表达基因包含较短且较少的内含子，这归因于转录和翻译过程中的经济性选择。另一方面，在植物中，已经表明高表达基因往往比低表达基因更长。在这项研究中，我们分析了组成对水稻和人类基因组组织的影响。我们证明，在富含 GC 的水稻基因中，高表达基因不如低表达基因紧凑。在 GC 含量低的类别中，高表达基因和低表达基因之间的基因紧凑性没有差异。然而，对于人类来说，由于其表达水平，GC 组成对基因紧凑性没有影响。我们还报告说，高表达的富含 GC 的水稻前体 mRNA 倾向于形成比低表达基因更少稳定的二级结构。然而，在去除内含子序列后，高表达的 mRNA 形成稳定的二级结构，而低表达的富含 GC 的基因则形成稳定的二级结构。我们认为，在富含 GC 的水稻基因中，长内含子通过调节前体 mRNA 二级结构稳定性来增强转录效率，因此这两个基因组（人类和水稻）的基因组组织背后的进化机制是不同的。
