Marmiesse Magali, Brodin Priscille, Buchrieser Carmen, Gutierrez Christina, Simoes Nathalie, Vincent Veronique, Glaser Philippe, Cole Stewart T, Brosch Roland
Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris Cedex 15, France.
Laboratoire de Génomique des Micro-organismes Pathogènes, Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris Cedex 15, France.
Microbiology (Reading). 2004 Feb;150(Pt 2):483-496. doi: 10.1099/mic.0.26662-0.
To better understand the biology and the virulence determinants of the two major mycobacterial human pathogens Mycobacterium tuberculosis and Mycobacterium leprae, their genome sequences have been determined recently. In silico comparisons revealed that among the 1439 genes common to both M. tuberculosis and M. leprae, 219 genes code for proteins that show no similarity with proteins from other organisms. Therefore, the latter 'core' genes could be specific for mycobacteria or even for the intracellular mycobacterial pathogens. To obtain more information as to whether these genes really were mycobacteria-specific, they were included in a focused macro-array, which also contained genes from previously defined regions of difference (RD) known to be absent from Mycobacterium bovis BCG relative to M. tuberculosis. Hybridization of DNA from 40 strains of the M. tuberculosis complex and in silico comparison of these genes with the near-complete genome sequences from Mycobacterium avium, Mycobacterium marinum and Mycobacterium smegmatis were undertaken to answer this question. The results showed that among the 219 conserved genes, very few were not present in all the strains tested. Some of these missing genes code for proteins of the ESAT-6 family, a group of highly immunogenic small proteins whose presence and number is variable among the genomically highly conserved members of the M. tuberculosis complex. Indeed, the results suggest that, with few exceptions, the 'core' genes conserved among M. tuberculosis H37Rv and M. leprae are also highly conserved among other mycobacterial strains, which makes them interesting potential targets for developing new specific anti-mycobacterial drugs. In contrast, the genes from RD regions showed great variability among certain members of the M. tuberculosis complex, and some new specific deletions in Mycobacterium canettii, Mycobacterium microti and seal isolates were identified and further characterized during this study. Together with the distribution of a particular 6 or 7 bp micro-deletion in the gene encoding the polyketide synthase pks15/1, these results confirm and further extend the revised phylogenetic model for the M. tuberculosis complex recently presented.
为了更好地了解两种主要的人类分枝杆菌病原体——结核分枝杆菌和麻风分枝杆菌的生物学特性及毒力决定因素，它们的基因组序列最近已被测定。计算机分析比较显示，在结核分枝杆菌和麻风分枝杆菌共有的1439个基因中，有219个基因编码的蛋白质与其他生物的蛋白质没有相似性。因此，后一类“核心”基因可能是分枝杆菌所特有的，甚至是细胞内分枝杆菌病原体所特有的。为了获得更多关于这些基因是否真的是分枝杆菌特异性基因的信息，将它们纳入了一个聚焦宏阵列，该阵列还包含来自先前定义的差异区域（RD）的基因，已知相对于结核分枝杆菌，卡介苗中不存在这些基因。对40株结核分枝杆菌复合群菌株的DNA进行杂交，并将这些基因与鸟分枝杆菌、海分枝杆菌和耻垢分枝杆菌的近完整基因组序列进行计算机分析比较，以回答这个问题。结果表明，在这219个保守基因中，几乎没有一个在所有测试菌株中都不存在。其中一些缺失基因编码ESAT-6家族的蛋白质，这是一组高度免疫原性的小蛋白质，其存在和数量在结核分枝杆菌复合群基因组高度保守的成员中是可变的。事实上，结果表明，除少数例外，在结核分枝杆菌H37Rv和麻风分枝杆菌中保守的“核心”基因在其他分枝杆菌菌株中也高度保守，这使得它们成为开发新型特异性抗分枝杆菌药物的有趣潜在靶点。相比之下，RD区域的基因在结核分枝杆菌复合群的某些成员中表现出很大的变异性，并且在本研究中鉴定并进一步表征了堪氏分枝杆菌、田鼠分枝杆菌和海豹分离株中的一些新的特异性缺失。连同编码聚酮合酶pks15/1的基因中一个特定的6或7bp微缺失的分布情况，这些结果证实并进一步扩展了最近提出的结核分枝杆菌复合群的修订系统发育模型。
