Bigi F, Alito A, Fisanotti J C, Romano M I, Cataldi A
Instituto de Biología Molecular, Centro de Investigaciones en Ciencias Veterinarias (CICV)/Instituto Nacional de Tecnología Agropecuaria (INTA), Moron, Argentina.
Infect Immun. 1995 Jul;63(7):2581-6. doi: 10.1128/iai.63.7.2581-2586.1995.
Serum from naturally infected cattle was used to identify a novel Mycobacterium bovis antigen from an expression library. The first recombinant product identified was a fusion protein with lacZ (55 kDa). A clone containing the whole gene was also obtained. This clone expressed a 38-kDa protein. A rabbit serum against the recombinant antigen reacts in M. bovis supernatants with two proteins of 36 and 34 kDa. The new protein was called P36/P34. The gene cloned has a deduced amino acid sequence with a predicted molecular mass of 28 kDa, showing a characteristic signal sequence for exportation. The protein bears partial homology to a 28-kDa protein from M. leprae. An interesting feature of the P36/P34 sequence is that it contains several PGLTS repeats, which are not present in the M. leprae protein. Antigenic determinants seem also to be conserved between the two proteins because sera from leprosy patients recognized the recombinant M. bovis protein. The discrepancy among the molecular mass deduced from the sequence (28 kDa), that of the recombinant protein in Escherichia coli (38 kDa), and that of the native protein in M. bovis (36 and 34 kDa) could be attributed to posttranslational modifications or to the high proline content that may alter the migration properties of the protein. This antigen seems to be immunodominant during bovine tuberculosis, because 8 of 9 serum specimens from diseased cattle are reactive. The homology among the M. leprae 28-kDa protein, the protein described in this article, and a recently described M. tuberculosis protein suggests the existence of a new protein family in mycobacteria.
利用自然感染牛的血清从一个表达文库中鉴定出一种新型牛分枝杆菌抗原。鉴定出的首个重组产物是一种与lacZ的融合蛋白（55 kDa）。还获得了一个包含完整基因的克隆。该克隆表达一种38 kDa的蛋白。一种针对该重组抗原的兔血清在牛分枝杆菌培养上清液中与两种分子量分别为36 kDa和34 kDa的蛋白发生反应。这种新蛋白被命名为P36/P34。克隆的基因推导的氨基酸序列预测分子量为28 kDa，显示出一个典型的输出信号序列。该蛋白与麻风分枝杆菌的一种28 kDa蛋白具有部分同源性。P36/P34序列的一个有趣特征是它包含几个PGLTS重复序列，而这些序列在麻风分枝杆菌蛋白中不存在。两种蛋白之间的抗原决定簇似乎也保守，因为麻风病人的血清能识别重组牛分枝杆菌蛋白。从序列推导的分子量（28 kDa）、大肠杆菌中重组蛋白的分子量（38 kDa）以及牛分枝杆菌中天然蛋白的分子量（36 kDa和34 kDa）之间的差异，可能归因于翻译后修饰或可能改变蛋白迁移特性的高脯氨酸含量。这种抗原在牛结核病期间似乎是免疫显性的，因为9份患病牛血清标本中有8份呈反应性。麻风分枝杆菌28 kDa蛋白、本文描述的蛋白以及最近描述的结核分枝杆菌蛋白之间的同源性表明分枝杆菌中存在一个新的蛋白家族。
