嗜盐古菌中氯视紫红质基因序列的遗传分析

采用PCR方法扩增了嗜盐古菌AB19、AB30和AJ5编码螺旋C至螺旋G的氯视紫红质（halorhodopsin，HR）蛋白基因片断和168rRNA基因（168rDNA），测定了它们的核苷酸序列，与已报道的，hr基因序列差异显著．获得AJ5 HR蛋白基因序列在Halobiforma属中尚属首次．对hr基因序列进行的遗传分析，包括GC含量、转换与颠换的比值、密码子使用偏好，表明hr基因面临进化选择和偏倚突变压的双重制约，是一类进化程度较高的基因．对比br基因编码蛋白螺旋C到G的序列发现它们具有相似的种属特征．采用BR和HR蛋白螺旋C到G序列构建系统发生树比传统的168rDNA序列具有优势，BR和HR可以作为两种新型的分子指标．

Genetic analysis of partial sequences of the gene for halorhodopsin in halophilic archaea

Partial DNA fragments encoding for helix C to G of halorhodopsin in halophilic archaea AB19, AB30 and AJ5, as well as the 16S rDNA sequences of AB19 and AB30 were proliferated by PCR, and their nueleotide sequences were determined. The detection of AJ5 hr gene is the first in the genus Halobiforma. The genetic analysis on hr gene including GC content, the ratio of transition and transvertion, and the eodon usage preference indicated that hr genes were highly evolved, which were restricted by deflected mutation pressure and evolutionary choice. On the basis of homology and phylogenetie analysis about hr and br partial fragments encoding helix C to G, hr and br genes had a similar species variation. And the phylogenetie tree based on the HR and BR helix C to G sequences was more predominant than the one based on 16S rDNA sequences. The two protein sequences could be marked as novel molecular indices.