Genetic Studies of the lac Repressor. VI. The B116 Repressor: an Altered lac Repressor Containing Amino Acids Specified by both the trp and lacI Leader Regions

Article Article scientifique Article Genetic Studies of the lac Repressor. VI. The B116 Repressor: an Altered lac Repressor Containing Amino Acids Specified by both the trp and lacI Leader Regions eng 1978 author Sommer Hans 63752 author Schmitz Albert author Schmeissner-Papazian Ursula 28518 author Miller Jeffrey H. author Wittmann Heinz-Gunter 457-469 10.1016/0022-2836(78)90090-6 0022-2836 https://linkinghub.elsevier.com/retrieve/pii/0022283678900906 Deletions extending into the trp operon at one terminus and the lacI control region at the other terminus have been examined. One of these, B116, ends within the trp leader sequence and eliminates the trp attenuator site, placing the synthesis of lac repressor under trp control. We have isolated and characterized the B116 repressor. The protein sequence of the aminoterminus of B116 shows that an additional 16 residues are added to the amino-terminal end of wild-type repressor. Moreover, a valine residue appears in place of methionine at position 17 (the original amino-terminal residue of the wild-type repressor). A comparison of the messenger RNA sequence of the trp leader region and of the I leader region demonstrates that the translation of the B116 repressor is initiated at an AUG codon within the trp leader sequence. The GUG initiation codon at the start point for translation of wild-type repressor is now read as valine, since it appears at an internal position (residue 17 of the altered repressor). The B116 repressor accumulates at levels as high as 1% of the soluble cell protein in trpR− strains. The efficiency of the trp leader initiation codon in translation suggests that in wild-type strains this AUG is also active in directing protein synthesis, which would result in a polypeptide consisting of 14 amino acids. We have examined the physical properties of the B116 repressor, which shows a marked tendency to form higher aggregates. Other characteristics of B116 are also described. Dewey 570 43 Département de biologie moléculaire 161 false Journal of Molecular Biology 123 3 50367edc-01c3-4521-a765-30482ef01c05 Article (Published version) Restricted 1-s2.0-0022283678900906-main.pdf 1652715 application/pdf restrictedAccess Faculté des sciences / Section de biologie / Département de biologie moléculaire

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Genetic Studies of the lac Repressor. VI. The B116 Repressor: an Altered lac Repressor Containing Amino Acids Specified by both the trp and lacI Leader Regions	Journal of Molecular Biology			1978	513	0

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Schmeissner-Papazian, Ursula