Eom Chi Yong, Kim Eungbin, Ro Young Tae, Kim Si Wouk, Kim Young Min
Department of Biology, Yonsei University, Seoul 120-749, Korea.
J Biochem Mol Biol. 2005 Nov 30;38(6):695-702. doi: 10.5483/bmbrep.2005.38.6.695.
The groESL bicistronic operon of a restricted facultative methylotrophic bacterium Methylovorus sp. strain SS1 DSM 11726 was cloned and characterized. It was found to consist of two ORFs encoding proteins with molecular masses of 11,395 and 57,396 daltons, which showed a high degree of homology to other bacterial GroES and GroEL proteins. The genes were clustered in the transcription order groES-groEL. Northern blot analyses suggested that the groESL operon is transcribed as a bicistronic 2.2-kb mRNA, the steady-state level of which was markedly increased by temperature elevation. Primer extension analysis demonstrated one potential transcription start site preceding the groESL operon, which is located 100 bp upstream of the groES start codon. The transcription start site was preceded by a putative promoter region highly homologous to the consensus sequences of Escherichia coli sigma 32-type heat shock promoter, which functioned under both normal and heat shock conditions in E. coli. Heat shock mRNA was maximally produced by Methylovorus sp. strain SS1 approximately 10 min after increasing the temperature from 30 to 42 degrees C. The groESL operon was also induced by hydrogen peroxide or salt shock.
对严格兼性甲基营养菌嗜甲基菌属菌株SS1 DSM 11726的groESL双顺反子操纵子进行了克隆和表征。发现它由两个开放阅读框组成，分别编码分子量为11395和57396道尔顿的蛋白质，这两种蛋白质与其他细菌的GroES和GroEL蛋白具有高度同源性。这些基因按groES - groEL的转录顺序成簇排列。Northern印迹分析表明，groESL操纵子转录为一个2.2 kb的双顺反子mRNA，其稳态水平在温度升高时显著增加。引物延伸分析表明，在groESL操纵子之前有一个潜在的转录起始位点，位于groES起始密码子上游100 bp处。转录起始位点之前是一个假定的启动子区域，与大肠杆菌σ32型热休克启动子的共有序列高度同源，该启动子在大肠杆菌的正常和热休克条件下均起作用。嗜甲基菌属菌株SS1在温度从30℃升高到42℃后约10分钟时产生的热休克mRNA最多。groESL操纵子也可被过氧化氢或盐胁迫诱导。
