赖型钩端螺旋体外膜蛋白基因结构比较性研究

A Comparative Study on the Structure of the Outer Membrane Protein Gene in Leptospira Serovar Lai

用 PCR方法扩增不同毒力赖型钩体 Omp L1基因片段 ,进行序列测定 ,用相关软件比较分析核苷酸序列、蛋白质二级结构以及限制性内切酶谱 .不同毒力赖型钩体均能扩增出960 bp的片段 ,非致病 Patoc株未能扩出相应片段 ,中国赖型参考株 Omp L1序列 ( Gene BankNo.AF2 50 31 8)与流感伤寒型相应序列比较有 98个核苷酸差异 ,同源性为 89.8% ,二级结构预测和氨基酸疏水图显示变异主要发生在跨膜蛋白的膜外区 ,其膜上成分并未明显变化 ;赖型强弱毒力株之间 Omp L1序列仅 8个核苷酸差异 ,6个氨基酸变异 ,且集中在 C末端 2 92 -30 5位氨基酸之间 ;限制性内切酶谱分析显示赖型 Omp L1基因位点发生特异变化 .结果提示 ,外膜蛋白 Omp L1基因是钩体保守性较强的致病标记 ;赖型钩体减毒致弱可能与 Omp

The OmpL 1 gene of Leptospira( L .) serovar lai was amplified and sequenced, and its nucleotide sequence, protein secondary structure and restriction endonuclease map were further analysed. A 960 bp fragment was amplified in various virluent L . interrogans serovar lai , not in L.bilexa patoc strain . In comparison with L.kirschneri ,98 nucleotides were found changed in OmpL 1 gene with a homology of 89.8%. The secondary structure predication and hydrophobicity plot that showed that the difference was located in extra nsmembrane field, not on the membrane.The OmpL 1 gene sequences only had 8 nucleotides and 6 amino acids difference between the strong and weak virulence serovar lai strains, and distributed in 292～305 amino acid sites of the carbon end. Restriction endonuclease map of OmpL 1 gene was also changed. These results suggested that the outer membrane protein OmpL 1 gene was the conservative pathogenic mark in leptospira, and the attenuation of serovar lai could be related with the local amino acids variation of the OmpL 1 gene.