De Reuse H, Danchin A
Unité Régulation de l'Expression Génétique, Institut Pasteur, Paris, France.
J Bacteriol. 1988 Sep;170(9):3827-37. doi: 10.1128/jb.170.9.3827-3837.1988.
The ptsH, ptsI, and crr genes, coding for three of the proteins of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) (HPr, enzyme I, and enzyme IIIGlc, respectively) have been studied by determination of their nucleotide sequence and analysis of their expression. The three genes constitute an operon, but analysis of the ptsH, ptsI, and crr transcripts by Northern (RNA) blotting revealed the existence of three major mRNA species. One encompassed the three cistrons, a second one the ptsH gene and part of the ptsI gene, and the third one only the distal gene crr. The short crr transcripts were initiated inside the ptsI open reading frame at points which were identified by S1 mapping. Expression of the genes was studied in vivo by using operon and protein fusions between the lacZ gene and the ptsH, ptsI, or crr gene on IncW low-copy-number plasmids. The present study showed that (i) the ptsH, ptsI, and crr genes exhibited high basal expression, (ii) transcription of the ptsH and ptsI genes was stimulated threefold by the cyclic AMP-cyclic AMP receptor protein complex and also by growth on glucose, but only in the presence of an active enzyme IIGlc, (iii) crr-specific expression was not sensitive to the complex or to growth on glucose, and (iv) under the growth conditions tested, the major part of crr transcription was initiated from internal promoters.
编码磷酸烯醇丙酮酸依赖性磷酸转移酶系统（PTS）的三种蛋白质（分别为HPr、酶I和酶IIIGlc）的ptsH、ptsI和crr基因，已通过测定其核苷酸序列并分析其表达进行了研究。这三个基因构成一个操纵子，但通过Northern（RNA）印迹分析ptsH、ptsI和crr转录本，发现存在三种主要的mRNA种类。一种包含这三个顺反子，第二种包含ptsH基因和部分ptsI基因，第三种仅包含远端基因crr。短的crr转录本在ptsI开放阅读框内的特定位置起始，这些位置通过S1作图得以确定。通过使用IncW低拷贝数质粒上lacZ基因与ptsH、ptsI或crr基因之间的操纵子和蛋白质融合体，在体内研究了这些基因的表达。本研究表明：（i）ptsH、ptsI和crr基因表现出高基础表达；（ii）ptsH和ptsI基因的转录受到环腺苷酸 - 环腺苷酸受体蛋白复合物以及在葡萄糖上生长的刺激，但仅在存在活性酶IIIGlc时；（iii）crr特异性表达对该复合物或在葡萄糖上生长不敏感；（iv）在所测试的生长条件下，crr转录的主要部分由内部启动子起始。
