Kong T H, Coates A R, Butcher P D, Hickman C J, Shinnick T M
Department of Medical Microbiology, St. George's Hospital Medical School, London, United Kingdom.
Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):2608-12. doi: 10.1073/pnas.90.7.2608.
A 65-kDa protein and a 10-kDa protein are two of the more strongly immunoreactive components of Mycobacterium tuberculosis, the causative agent of tuberculosis. The 65-kDa antigen has homology with members of the GroEL or chaperonin-60 (Cpn60) family of heat shock proteins. The 10-kDa antigen has homology with the GroES or chaperonin-10 family of heat shock proteins. These two proteins are encoded by separate genes in M. tuberculosis. The studies reported here reveal that M. tuberculosis contains a second Cpn60 homolog located 98 bp downstream of the 10-kDa antigen gene. The second Cpn60 homolog (Cpn60-1) displays 61% amino acid sequence identity with the 65-kDa antigen (Cpn60-2) and 53% and 41% identity with the Escherichia coli GroEL protein and the human P60 protein, respectively. Primer-extension analysis revealed that transcription starts 29 bp upstream of the translation start of the Cpn60-1 homolog and protein purification studies indicate that the cpn60-1 gene is expressed as an approximately 60-kDa polypeptide.
65千道尔顿蛋白和10千道尔顿蛋白是结核分枝杆菌（结核病的病原体）中免疫反应较强的两种成分。65千道尔顿抗原与热休克蛋白的GroEL或伴侣蛋白60（Cpn60）家族成员具有同源性。10千道尔顿抗原与热休克蛋白的GroES或伴侣蛋白10家族具有同源性。这两种蛋白由结核分枝杆菌中的不同基因编码。此处报道的研究表明，结核分枝杆菌在10千道尔顿抗原基因下游98 bp处含有第二个Cpn60同源物。第二个Cpn60同源物（Cpn60-1）与65千道尔顿抗原（Cpn60-2）的氨基酸序列同一性为61%，与大肠杆菌GroEL蛋白和人P60蛋白的同一性分别为53%和41%。引物延伸分析表明转录起始于Cpn60-1同源物翻译起始上游29 bp处，蛋白质纯化研究表明cpn60-1基因表达为约60千道尔顿的多肽。
