脊椎动物TYR基因的序列特征选择压力及结构建模
关键词：脊椎动物；酪氨酸酶；序列；选择压力；结构建模
Abstract: Tyrosinase, which is widely present in various organisms, is a copper-containing enzyme that is mainly involved in the biosynthesis of melanin. Bioinformatics method was used to investigate sequence features and evolutionary pattern of vertebrate TYR genes and to construct three dimensional structures of representative proteins. Phylogenetic analysis indicated that gene tree of vertebrate TYR proteins was highly consistent with species tree. Gene structure analysis showed that 5 exons were shared by most vertebrate TYR genes, DrTYR and OlTYR genes had 6 exons, and SsTYR gene had 9 exons. Analysis of protein sequence demonstrated that the common TYROSINASE domain was shared by vertebrate TYR proteins. In addition, different TYR proteins from distinct species had conserved motif organizations, but Motif 13 is specific to mammal TYR proteins. Selection pressure analysis was performed on the vertebrate TYR proteins using site-model and branch-site model. No amino acid sites were under positive selection via site model. However, three branches under positive selection were identified by branch-site model. Accordingly, 26 positively selected sites were identified from the ancestral branch of horse and pig. 27 positively selected sites were found from the pig branch. Only 1 positively selected site was identified from the ancestral branch of chicken and Zebra finch. These positively selected sites were distributed on different primary and secondary structures of TYR proteins, but were intensively distributed on the same area of three dimensional structures, suggesting that these sites were closely coupled to specific functions. This results provide valuable references for investigation of biological function and critical amino acid sites of vertebrate TYR proteins.
Key words: Vertebrate, Tryosinase, Sequence, Selection pressure, Structural Modelling
目 录
摘 要 1
引言 2
1．材料与方法 3
1.1物种抽样与酪氨酸酶序列获取 3
1.2基因结构与蛋白序列特征分析 4
1.3蛋白序列比对与系统进化分析 4
1.4选择压力检测与蛋白结构模拟 4
2.结果与分析 5
2.1脊椎动物酪氨酸酶的系统进化分类 5
2.2脊椎动物酪氨酸酶基因的结构特征 6
2.3脊椎动物酪氨酸酶的蛋白序列特征 7
2.4脊椎动物酪氨酸酶的选择压力 9
2.5关键氨基酸位点在酪氨酸酶蛋白结构中的分布 11
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