Ballard S A, Segers R P, Bleumink-Pluym N, Fyfe J, Faine S, Adler B
Department of Microbiology, Monash University, Clayton, Victoria, Australia.
Mol Microbiol. 1993 May;8(4):739-51. doi: 10.1111/j.1365-2958.1993.tb01617.x.
A chromosomal gene library of Leptospira interrogans serovar copenhageni strain Wijnberg was constructed in phage lambda gt11. Plaque immunoassay with R alpha P64 antiserum identified one clone expressing a putative groEL homologue. DNA sequence analysis of the 2.4 kb EcoRI-Bam HI cloned fragment from strain Wijnberg revealed two open reading frames encoding polypeptides of 10.5 kDa (Hsp10) and 58 kDa (Hsp58). Sequence comparison of the deduced amino acid sequences of these ORFs confirmed the operon as the groE equivalent of Leptospira. Transcriptional analysis suggested that this operon is primarily under the control of an E sigma 70 promoter element. However, both Hsp10 and Hsp58 were overexpressed under heat-shock conditions as determined by [35S]-methionine pulse labelling experiments. As no functional heat-shock promoter could be identified, a 9bp inverted repeat, located between the transcription and translation start sites, may play a role in the upregulation of this operon under heat-shock conditions, similar to mechanisms described for several Gram-positive organisms.
问号钩端螺旋体哥本哈根血清型菌株Wijnberg的染色体基因文库构建于噬菌体λgt11中。用RαP64抗血清进行噬菌斑免疫测定，鉴定出一个表达假定groEL同源物的克隆。对来自菌株Wijnberg的2.4 kb EcoRI - Bam HI克隆片段进行DNA序列分析，发现两个开放阅读框，分别编码10.5 kDa（Hsp10）和58 kDa（Hsp58）的多肽。这些开放阅读框推导的氨基酸序列的序列比较证实该操纵子相当于钩端螺旋体的groE。转录分析表明，该操纵子主要受E sigma 70启动子元件的控制。然而，通过[35S] - 甲硫氨酸脉冲标记实验确定，在热休克条件下Hsp10和Hsp58均过表达。由于未鉴定到功能性热休克启动子，位于转录和翻译起始位点之间的一个9bp反向重复序列可能在热休克条件下该操纵子的上调中起作用，类似于几种革兰氏阳性菌所描述的机制。
