Interaction of the Trp Repressor with Trp Operator DNA Fragments
Overview
Authors
Affiliations
The interaction of the trp repressor with several trp operator DNA fragments has been examined by DNA gel retardation assays and by circular dichroism, in the absence and presence of the corepressor L-tryptophan. The holorepressor binds stoichiometrically to both the trpO and aroH operators, forming 1:1 complexes. In the presence of excess protein, additional complexes are formed with these operator fragments. The relative electrophoretic mobilities of the 1:1 complexes differ significantly for trp and aroH operators, indicating that they differ substantially in gross structure. A mutant trp operator, trpOc, has low affinity for the holorepressor, and forms only complexes with stoichiometries of 2:1 (repressor: DNA) or higher, which have a very low electrophoretic mobility. Specific binding is also accompanied by a large increase in the intensity of the near ultraviolet circular dichroism, with only a small blue shift, which is consistent with significant changes in the conformation of the DNA. Large changes in the chemical shifts of three resonances in the 31P NMR spectrum of both the trp operator and the aroH operator occur on adding repressor only in the presence of L-tryptophan, consistent with localised changes in the backbone conformation of the DNA.
Arakawa T, Nakagawa M, Sakuma C, Tomioka Y, Kurosawa Y, Ejima D Eur Biophys J. 2023; 53(1-2):1-13.
PMID: 38160206 DOI: 10.1007/s00249-023-01694-5.
Determining binding sites in protein-nucleic acid complexes by cross-saturation.
Lane A, Kelly G, Ramos A, Frenkiel T J Biomol NMR. 2001; 21(2):127-39.
PMID: 11727976 DOI: 10.1023/a:1012486527215.
Solution structure of the ATF-2 recognition site and its interaction with the ATF-2 peptide.
Conte M, Lane A, Bloomberg G Nucleic Acids Res. 1997; 25(19):3808-15.
PMID: 9380502 PMC: 146960. DOI: 10.1093/nar/25.19.3808.
Kralicek A, Wilson P, RALSTON G, Wake R, King G Nucleic Acids Res. 1997; 25(3):590-6.
PMID: 9016600 PMC: 146460. DOI: 10.1093/nar/25.3.590.
Gunes C, Muller-Hill B Mol Gen Genet. 1996; 251(3):338-46.
PMID: 8676876 DOI: 10.1007/BF02172524.