BACILLUS-SUBTILIS PUR OPERON EXPRESSION AND REGULATION
BACILLUS-SUBTILIS PUR OPERON EXPRESSION AND REGULATION
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DOI：
10.1128/jb.171.4.2136-2141.1989
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发表时间：
1989-04-01
影响因子：
3.2
通讯作者：
ZALKIN, H
中科院分区：
文献类型：
--
作者：
EBBOLE, DJ;ZALKIN, H
枯草芽孢杆菌pur操纵子是一个由12个基因组成的基因簇，purEKB-purC(orf)QLF-purMNH(J)-purD，由顺胞间隙隔开的重叠编码单元组成。构建大肠杆菌lacZ的pureE、purC和purM翻译融合体，分别为各组的第一个基因。整合到染色体pur操纵子的基因融合分析排除了顺反子间区域内部启动子的可能性，并支持转录来自单个。sigma的观点。43个启动子位于操纵子的5'端。酶和mRNA的测量表明，转录调控仅发生在操纵子的5'末端。的相对水平。purE-lacZ、purC-lacZ和purM-lacZ中的-半乳糖苷酶分别在抑制和非抑制条件下测定。这些结果表明，purC-lacZ的表达量比purE-lacZ高3.0 ~ 6.8倍，因为purC-lacZ的翻译效率更高。purC-lacZ翻译效率的提高伴随着嘌呤调控的部分逃逸。这种对purC-lacZ的异常影响是转录后调控的唯一提示。
The Bacillus subtilis pur operon is a 12-gene cluster, purEKB-purC(orf)QLF-purMNH(J)-purD, organized in groups of overlapping coding units separated by intercistronic gaps. Translational fusions of Escherichia coli lacZ were constructed to pureE, purC, and purM, the first gene of each group. Analyses of gene fusions integrated into the chromosomal pur operon exclued the possibility of internal promoters in intercistronic regions and support the view that transcription is from the single .sigma.43 promoter at the 5'' end of the operon. Enzyme and mRNA measurements indicate that transcriptional regulation occurs solely at the 5'' end of the operon. The relative levels of .beta.-galactosidase from purE-lacZ, purC-lacZ, and purM-lacZ were determined under repressing and nonrepressing conditions. These results indicate that expression of purC-lacZ was 3.0- to 6.8-fold higher than purE-lacZ because of enhanced translational efficiency. The enhanced translational efficiency of purC-lacZ was accompanied by a partial escape form regulation by purine. This anomalous effect on purC-lacZ was the only suggestion for posttranscriptional regulation.