真菌核心组蛋白基因的分子特点与进化动力学模式  

Molecular characters and long-term evolutionary pattern of fungi′s core histone multigenes

作　　者：鞠建峰[1] 赵国焓[1] 许晓风[1] 

机构地区：[1]南京师范大学生命科学学院,南京210097

出　　处：《安徽农业大学学报》2007年第3期440-445,共6页Journal of Anhui Agricultural University

摘　　要：统计了不同真菌36个核心组蛋白基因的核苷酸组成与分布特点及密码子适应指数(CAI),分类计算了这些基因在种内及种间同义位点差异(pS)和非同义位点差异(pN)。结果发现:1)真菌H2A、H2B、H3、H4基因的平均GC%含量依次为:42.2、43.7、43.3和42.7,第3位密码子GC%含量依次为:34.7、42.6、32.0和30.9,平均CAI依次为:0.698、0.745、0.699和0.745;2)真菌4种组蛋白基因的pS和pN表现不同,其中H3和H4表现为pSpN,符合birth-and-death进化模式,H2A和H2B表现为pS≈pN,不符合birth-and-death进化模式;3)酵母的H2A和H2B甚至表现出了pN pS的情形,与协调进化相一致。真菌组蛋白基因的这些分子特点与进化动力学模式和其它生物组蛋白基因的明显不同。In this study, we examined both the molecular characters and long-term evolutionary pattern of fungi＇s core histone multigene family. We analyzed the nucleotide composition, nucleotide distribution and codon adaptation index （CAI） of 36 core histone multigenes from 9 species of fungi, and calculated their proportion of synonymous nucleotide differences （pS） and nonsynonymous nucleotide differences （pN） both within and between species to determine whether concerted evolution or purifying selection was the major factor for the evolution of these multigenes. The results are as follows ： 1 ） fungi＇s H2A, H2B, H3 and H4 multigenes all have a low GC% content and a low GC3s% with the value of 42.2,43.7,43.3,42. 7, and 34.7,42. 6,32.0,30. 9 respectively ; Their average CAI values are 0. 698,0. 745,0. 699 and 0. 745 ;2）their pS and pN behaviors both within and between species are quite different with the H2A＇s and H2B＇s showing pS≈pN and H3＇s and H4＇s showing pS 〉〉 pN, indicating that the H3 and H4 are according the birth-and-death model of evolution under strong purifying selection while the H2A and H2B not;3 ）yeast＇s H2A and H2B are very special, for their pS and pN behaved as pN 〉〉pS both within and between species ,which indicates that the concerted evolution is the major evolutionary pattern for these two kinds of histone genes.

关 键 词：真菌组蛋白 分子进化 进化模式 

分 类 号：Q755[生物学—分子生物学]