NUCLEOTIDE-SEQUENCE AND EXPRESSION OF ESCHERICHIA-COLI TRPR, THE STRUCTURAL GENE FOR THE TRP APOREPRESSOR
NUCLEOTIDE-SEQUENCE AND EXPRESSION OF ESCHERICHIA-COLI TRPR, THE STRUCTURAL GENE FOR THE TRP APOREPRESSOR
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DOI：
10.1073/pnas.77.12.7117
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
YANOFSKY, C
中科院分区：
文献类型：
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作者：
GUNSALUS, RP;YANOFSKY, C
克隆了大肠杆菌trpR基因的核苷酸序列。大肠杆菌进行了测定。该基因编码长度为108个氨基酸残基的多肽（MW 12，356）。对纯化的脱辅基阻遏物进行了氨基端、羧基端和总氨基酸分析，结果与推导的氨基酸序列一致，并确定了结构基因的翻译起始密码子和终止密码子。体外合成trpR mRNA的转录起始位点位于翻译起始位点之前的56个碱基对处。转录起始位点两侧的核苷酸序列与trp操纵子同源。当被L-色氨酸激活时，纯化的trp去辅阻遏物保护该区域的限制性位点（推测为trpR操纵基因）不被相应的限制性内切酶切割。结合的RNA聚合酶保护相同的限制性位点。这些发现以及trp阻遏物在体外抑制转录起始的额外观察结果确立了在trpR操纵子的调控区中操纵子和启动子序列的功能重叠。这些发现表明，trpR的表达是自动调节的。
The nucleotide sequence of trpR of E. coli was determined. This gene codes for a polypeptide (MW 12,356) that is 108 amino acid residues in length. NH2-terminal, COOH-terminal and total amino acid analyses of purified aporepressor agree with the deduced amino acid sequence and establish the translation start and stop codons of the structural gene. The transcription start site for trpR mRNA synthesis in vitro was shown to be 56 base pairs prior to the translation start site. The nucleotide sequence on either side of the transcription start site is homologous to the trp operon operator. Purified trp aporepressor, when activated by L-tryptophan, protects restriction sites in this region, the presumed trpR operator, from cleavage by the respective restriction endonucleases. Bound RNA polymerase protects the same restriction sites. These findings and the additional observation that trp repressor inhibits transcription initiation in vitro establish that there is a functional overlap of operator and promoter sequences in the regulatory region of the trpR operon. These findings indicate that expression of trpR is autoregulatory.