翘嘴鲌血红蛋白基因Hbs的克隆、分子特征及系统进化分析

CLONING, MOLECULAR CHARACTERISTIC AND PHYLOGENETICS OF HEMOGLOBIN GENES IN CULTER ALBURNUS

  • 摘要: 研究通过克隆翘嘴鲌(Culter alburnus)血红蛋白基因, 分析血红蛋白的分子特征及系统进化, 探讨鱼类耐低氧的可能成因。研究克隆了翘嘴鲌血红蛋白家族中Hba1/2和Hbb1/2 cDNA序列, 翻译后分别得到143、143、147和147个氨基酸。蛋白二级结构分析表明Hba1/2和Hbb1/2蛋白分别包含7和8个螺旋域、14和13个α1β2结合残基、12和16个亚铁血红素结合残基, 均有16个α1β1结合残基, 只有Hba1/2蛋白具有6个Bohr效应残基。与两栖类和哺乳类相比, 鱼类Hba和Hbb蛋白功能域上分别有10和5个氨基酸残基替换位点, 这很可能是为了使其适应水中的低氧环境。而耐低氧与不耐低氧鱼类相比, 其蛋白二级结构并未发现一致性的替换, 这表明鱼类的耐低氧特征很可能是受到上游信号通路的调控。通过系统发育关系表明Hba1/2和Hbb1/2基因亚型的复制事件很可能发生在脊椎动物全基因组复制之后且硬骨鱼类全基因组复制事件之前。值得注意的是在系统进化树上, 与其他鱼类相比翘嘴鲌和斑马鱼在Hba1/2和Hbb1基因上有更近的亲缘关系, 这很可能是由于其同属鲤形目且均不耐低氧所致。研究首次克隆了翘嘴鲌血红蛋白家族基因, 分析其分子特征及与其他物种的系统发育关系, 并探讨了鱼类耐低氧的可能成因, 为鱼类的耐低氧生物学研究提供了理论基础与潜在方向。

     

    Abstract: Hemoglobin is one of the most important proteins for aerobic metabolism in vertebrate. The studies of Hb are more in Mammalia, but less in fishes with low-oxygen environment. This study cloned Hba1/2 and Hbb1/2 cDNA sequences of Culter alburnus (C. alburnus) hemoglobin, which encode 143, 143, 147 and 147 of amino acids, respectively. The second structure analysis of proteins indicated that Hba1/2 and Hbb1/2 included 7 and 8 helical regions, 14 and 13 α1β2 interfaces, 12 and 16 heme bindings, 16 and 16 α1β1 interfaces, respectively, and 6 Bohr effect residues only for Hba1/2. Compared with amphibians and mammalia, there were 10 and 5 amino acid substitutions in fishes of Hba and Hbb functional domains, which may be used to adapt to hypoxia. However, compared with tolerant and intolerant hypoxia fishes, we did not find any coherent substitution in the second structure of proteins, indicating that the tolerant hypoxia trait of fish may be regulated by upstream signal pathways. The phylogenetic relationship showed the duplication events of Hba1/2 and Hbb1/2 isoforms may occurre after vertebrate and before teleost of whole-genome duplications. Interestingly, in the phylogenetic trees, the genetic relationships of C. alburnus and Danio rerio of Hba1/2 and Hbb1 were closer than those of C. alburnus and other fishes, probably because both C. alburnus and Danio rerio belong to Cypriniformes and intolerant to hypoxia. This study cloned Hba1/2 and Hbb1/2 cDNA sequences of C. alburnus hemoglobin, analyzed molecular characteristics and phylogenetic relationships with others, and discussed the possible causes of fish tolerance to hypoxia. These findings provide a theoretical basis and potential direction for fish tolerant hypoxia biology.

     

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