Characterization of the Lactococcus lactis lactose operon promoter: contribution of flanking sequences and LacR repressor to promoter activity
Characterization of the Lactococcus lactis lactose operon promoter: contribution of flanking sequences and LacR repressor to promoter activity
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乳酸乳球菌乳糖操纵子启动子的表征：侧翼序列和 LacR 阻遏物对启动子活性的贡献
DOI：
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发表时间：
1992
影响因子：
3.2
通讯作者：
W. M. D. Vos
中科院分区：
文献类型：
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作者：
Rutger J. vAN;Rooijen;Mike J. Gasson;W. M. D. Vos
我们确定了乳酸乳球菌 8-kb 乳糖操纵子 (lacABCDFEGX) 启动子的位置、活性和调控，该操纵子编码乳糖磷酸转移酶系统和塔格糖 6-磷酸途径的酶。 lac启动子序列与革兰氏阳性菌所描述的共有启动子密切对应，并且与差异转录的lacR基因的启动子处于背对背构型，该基因编码LacR阻遏物。确定了诱导（乳糖）和非诱导（葡萄糖）条件下使用的转录起始位点。可以在单个限制性片段上分离的最小启动子区域包括范围从-75到+42的序列。通过使用与无启动子氯霉素乙酰转移酶报告基因的转录融合，在大肠杆菌和乳酸乳球菌菌株中研究了侧翼序列和 lacR 基因的存在对启动子活性和调节的影响。结果表明，lac操纵子的转录调控是通过LacR阻遏物、lac启动子以及lacR和lacA基因之间非编码区序列之间的相互作用介导的。最小启动子区域侧翼的序列似乎在乳酸乳球菌中比在大肠杆菌中（1.3 至 5 倍）更多地增强 lac 启动子活性（5 至 38 倍）。
We determined the location, activity, and regulation of the promoter of the Lactococcus lactis 8-kb lactose operon (lacABCDFEGX), which encodes the enzymes of the lactose phosphotransferase system and the tagatose 6-phosphate pathway. The lac promoter sequence corresponds closely to the consensus promoter described for gram-positive bacteria and is located in a back-to-back configuration with the promoter of the divergently transcribed lacR gene, which encodes the LacR repressor. The transcription start sites used under induced (lactose) and noninduced (glucose) conditions were determined. The minimal promoter region that could be isolated on a single restriction fragment included sequences ranging from -75 to +42. The effect of the presence of flanking sequences and the lacR gene on promoter activity and regulation was studied in Escherichia coli and L. lactis strains by using transcriptional fusions with promoterless chloramphenicol acetyltransferase reporter genes. The results showed that transcriptional regulation of the lac operon is mediated by the interaction between the LacR repressor, the lac promoter, and sequences in the noncoding region between the lacR and lacA genes. Sequences flanking the minimal promoter region appeared to enhance lac promoter activity much more in L. lactis (5- to 38-fold) than in E. coli (1.3- to 5-fold).