Missiakas D, Georgopoulos C, Raina S
Département de Biochimie Médicale, Centre Médical Universitaire, Genève, Switzerland.
J Bacteriol. 1993 May;175(9):2613-24. doi: 10.1128/jb.175.9.2613-2624.1993.
We have identified a new heat shock gene, designated htpY, located 700 bp upstream of the dnaK dnaJ operon. We cloned it and showed that it is transcribed clockwise vis-à-vis the Escherichia coli genetic map, in the same direction as the dnaK dnaJ operon. The htpY gene encodes a 21,193-Da polypeptide. Promoter mapping experiments and Northern (RNA) analysis showed that the htpY gene belongs to the classical heat shock gene family, because the transcription from its major promoter is under the positive control of the rpoH gene product (sigma 32) and resembles canonical E sigma 32-transcribed consensus promoter sequences. This conclusion has been strengthened by the construction and analysis of a phtpY-lacZ promoter fusion. Despite the fact that htpY null bacteria are viable, the expression of various E sigma 32 heat shock promoters is significantly decreased, suggesting that HtpY plays an important role in the regulation of the heat shock response. Consistent with this interpretation, overproduction of the HtpY protein results in a generalized increase of the heat shock response in E. coli.
我们鉴定出了一个新的热休克基因，命名为htpY，它位于dnaK dnaJ操纵子上游700 bp处。我们对其进行了克隆，并证明它相对于大肠杆菌遗传图谱是顺时针转录的，与dnaK dnaJ操纵子的转录方向相同。htpY基因编码一种21,193道尔顿的多肽。启动子定位实验和Northern（RNA）分析表明，htpY基因属于经典热休克基因家族，因为其主要启动子的转录受rpoH基因产物（σ32）的正调控，并且类似于典型的E σ32转录的共有启动子序列。phtpY-lacZ启动子融合体的构建和分析进一步证实了这一结论。尽管htpY基因缺失的细菌能够存活，但各种E σ32热休克启动子的表达显著降低，这表明HtpY在热休克反应的调控中起重要作用。与此解释一致的是，HtpY蛋白的过量表达导致大肠杆菌中热休克反应普遍增强。
