红平红球菌复苏促进因子基因克隆及功能域分析

Gene Cloning and Functional Domains Analysis of Recovery Promoting Factors in Rhodococcus erythropolis rpf

复苏促进因子（Rpf）广泛存在于高G＋C含量的革兰氏阳性细菌中,与细菌生长及抵抗不良环境有关,不同细菌Rpf种类和数量有一定差异。红平红球菌（Rhodococcus erythropolis）KB1分离自石油污染土壤,具有高效石油降解能力和环境适应性。为探索Rpf在红平红球菌KB1适应环境过程中作用,设计了复苏因子基因特异引物,从红平红球菌KB1基因组DNA扩增出4种rpf基因。序列分析发现4种基因分别与藤黄微球菌（Micrococcus luteus）rpf基因,结核分枝杆菌（Mycobacterium tuberculosis）rpfB、rpfC及链霉菌（Streptomyces coelicolor）rpfB相似性较高。4个rpf基因编码蛋白都有一个类似Mt细胞复苏促进因子Rpf域,由大约70个氨基酸组成。其中Rpf-1与结核分枝杆菌、链霉菌RpfC相似,只含1个Rpf结构域;Rpf-2与结核分枝杆菌RpfB相似,含有1个Rpf域、1个G5域和2个DUF348;Rpf-3与链霉菌RpfB相似,含有1个Rpf域、G5域和3个DUF348;Rpf-4与藤黄微球菌Rpf相似,含1个Rpf域和1个LysM域。Rpf-2、Rpf-3含信号肽序列,Rpf-1、Rpf-4不含信号肽。

Recovery promoting factors（Rpf） widely exist in gram-positive bacteria with high G＋C. They are related to bacterial growth and resistance to adverse environment. The amount and type of Rpfs vary in different bacteria. Rhodococcus erythropolis KB1 was screened from oil contaminated soil, which had high efficient oil degradation and environmental adaptability. In order to explore the role of Rpf in the adaptation process of KB1, the primers of rpf genes were designed, and 4 rpf genes were amplified from the genome DNA of R. erythropolis KB1. It was found that 4 genes respectively had high similarities with Micrococcus luteusrpf genes, Mycobacterium tuberculosi rpfB, rpfC genes and Streptomyces coelicolor rpf B genes. The proteins encoded by 4 rpf genes had Rpf domain similar to Mt cell promoting recovery factor, which approximately consisted of 70 amino acids. Rpf-1 had only one Rpf domain, which was similar to RpfC of Mycobacterium tuberculosis and Streptomyces coelicolor. Rpf-2 had one Rpf domain, one G5 domain and two DUF348, which was similar with Rpf B of Mycobacterium tuberculosis. Rpf-3 had one Rpf domain, one G5 domain and three DUF348, which was similar with RpfB of Streptomyces coelicolor. Rpf-4 had one Rpf domain and one Lys M domain, which was similar with Rpf of Micrococcus luteus. Rpf-2 and Rpf-3 contained one signal peptide respectively, while Rpf-1 and Rpf-4 contain no signal peptide.