卡氏肺孢子虫肌动蛋白I编码基因的结构、表达及系统发育分析
Structure, expression and phylogenetic analysis of the gene encoding actin I in Pneumocystis carinii.
作者信息
Fletcher L D, McDowell J M, Tidwell R R, Meagher R B, Dykstra C C
机构信息
Department of Pathology, School of Medicine, University of North Carolina, Chapel Hill 27599.
出版信息
Genetics. 1994 Jul;137(3):743-50. doi: 10.1093/genetics/137.3.743.
Actin is a major component of the cytoskeleton and one of the most abundant proteins found in eukaryotic cells. Comparative sequence analysis shows that this essential gene has been highly conserved throughout eukaryotic evolution making it useful for phylogenetic analysis. Complete cDNA clones for the actin-encoding gene were isolated and characterized from Pneumocystis carinii purified from immunosuppressed rat lungs. The nucleotide sequence encodes a protein of 376 amino acids. The predicted actin protein of P. carinii shares a high degree of conservation to other known actins. Only one major actin gene was found in P. carinii. The P. carinii actin sequence was compared with 30 other actin sequences. Gene phylogenies constructed using both neighbor-joining and protein parsimony methods places the P. carinii actin sequence closest to the majority of the fungi. Since the phylogenetic relationship of P. carinii to fungi and protists has been questioned, these data on the actin gene phylogeny support the grouping of P. carinii with the fungi.
肌动蛋白是细胞骨架的主要成分，也是真核细胞中含量最丰富的蛋白质之一。比较序列分析表明，这个必需基因在整个真核生物进化过程中高度保守，因此可用于系统发育分析。从免疫抑制大鼠肺中纯化得到的卡氏肺孢子虫中分离并鉴定了编码肌动蛋白基因的完整cDNA克隆。核苷酸序列编码一个由376个氨基酸组成的蛋白质。预测的卡氏肺孢子虫肌动蛋白与其他已知肌动蛋白具有高度的保守性。在卡氏肺孢子虫中仅发现一个主要的肌动蛋白基因。将卡氏肺孢子虫的肌动蛋白序列与其他30个肌动蛋白序列进行了比较。使用邻接法和蛋白质简约法构建的基因系统发育树将卡氏肺孢子虫的肌动蛋白序列定位为最接近大多数真菌的序列。由于卡氏肺孢子虫与真菌和原生生物的系统发育关系一直存在疑问，这些关于肌动蛋白基因系统发育的数据支持将卡氏肺孢子虫与真菌归为一组。
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