Bharanidharan D, Bhargavi G Ramya, Uthanumallian Kavitha, Gautham N
Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India.
Biochem Biophys Res Commun. 2004 Mar 19;315(4):1097-103. doi: 10.1016/j.bbrc.2004.01.129.
We studied the correlations between amino acid composition and mononucleotide and dinucleotide frequencies in 115 bacterial genomes of varying G+C content. Observed amino acid frequencies were compared with those expected from the actual mononucleotide and dinucleotide frequencies. Both mononucleotide and dinucleotide frequencies correlate well with the amino acid frequency, with dinucleotide frequencies doing so better. Despite the strong correlations, some of the observed amino acid frequencies, in particular for Arg, Val, Asp, Glu, Ser, and Cys, were consistently different from predicted values in all genomes. We suggest that this variation from predicted values is a consequence of selection pressure at the level of amino acids, while the close correspondence to the predictions in residues such as Thr, Phe, Lys, and Asn arises only from mutation and selection pressure at the level of the nucleic acid sequences.
我们研究了115个不同G+C含量的细菌基因组中氨基酸组成与单核苷酸和二核苷酸频率之间的相关性。将观察到的氨基酸频率与根据实际单核苷酸和二核苷酸频率预期的频率进行比较。单核苷酸和二核苷酸频率均与氨基酸频率密切相关，二核苷酸频率的相关性更好。尽管存在很强的相关性，但在所有基因组中，一些观察到的氨基酸频率，特别是Arg、Val、Asp、Glu、Ser和Cys的频率，始终与预测值不同。我们认为，这种与预测值的差异是氨基酸水平选择压力的结果，而Thr、Phe、Lys和Asn等残基与预测值的密切对应仅源于核酸序列水平的突变和选择压力。
