How lac Repressor Binds to DNA

Adler, Klaus; Beyreuther, Konrad; Fanning, Ellen; Geisler, Norbert; Gronenborn, Bruno; Klemm, Alex; Müller‐Hill, Benno; Pfahl, Magnus; Schmitz, A.

doi:10.1038/237322a0

Cited by 231 publications

(94 citation statements)

References 19 publications

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“…These values are in good agreement with chemical and physicochemical measurements [2,10,40,43,44]. Partial sequences of lac repressor published previously [39,40,45,46] are confirmed by the present results.…”

Section: Discussionsupporting

confidence: 81%

“…TXXIII, a ditryptic fragment with an intact Lys-Pro bond, and methionine as N-terminal residue, originates from the extreme N-terminal end of the molecule [lo]. Its sequence, shown in Table 7, confirms results reported earlier [39,40].…”

Section: Purification and Sequence Analysis Of The Tryptic Peptidessupporting

confidence: 75%

“…It is known that the tyrosine-rich, hydrophilic N-terminal region is involved in operator binding of lac repressor [39,55] and it is tempting to speculate that the region adjacent to this N-terminal part plays a special role in the transmission of the allosteric change during induction Fig. 5.…”

Section: Discussionmentioning

confidence: 99%

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Amino‐Acid Sequence of lac Repressor from Escherichia coli

Beyreuther

Adler

Fanning

et al. 1975

European Journal of Biochemistry

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The lac repressor from Escherichia coli, composed of four identical subunits with a molecular weight of 37 160, was carboxymethylated and fragmented by tryptic digestion and cyanogen bromide treatment. Using ion-exchange chromatography, gel filtration and preparative thin-layer electrophoresis and chromatography 29 of the 30 tryptic peptides were isolated in pure form. Direct Edman degradation and the dansyl-Edman technique were used to determine the sequence of the small tryptic peptides. Special emphasis was put on the sequence determination of the six large tryptic fragments which together account for 177 residues, corresponding to 51% of the repressor subunit with its 347 residues. The large tryptic fragments were analyzed after fragmentation with chymotrypsin, thermolysin and dipeptidyl aminopeptidase I. Thus the sequence of all 30 tryptic peptides could be deduced. The complete sequences of all cyanogen bromide fragments were deduced from peptides obtained by tryptic, chymotryptic and thermolytic digestion of the individual fragments and by automated stepwise Edman degradation of lac repressor and of the large cyanogen bromide fragments. The order of the cyanogen bromide fragments was given by overlapping tryptic peptides. The resulting amino acid composition of the monomer is Aspls, Asn,,, Thr18, Ser,,, GluI4, Gln2,, Prol3, Gly,,, Ala,, CYS,, Val,,, Met,, h7, Leu,,, Tyr,, Phe,, Trp,, Lys,,, His,, Arg,,.The sequence of lac repressor shows no similarities with that of other proteins known to bind to DNA or RNA. The N-terminal55 residues contain two homologous regions. This part of the sequence which is involved in lac operator binding might have been formed by gene duplication.The lactose ( l u c ) repressor of Escherichia coli controls the lac operon, which consists of three structural genes (z, y and a ) encoding fl-galactosidase, galactosidase permease, and thiogalactoside transacetylase, respectively. The lac operon also contains two controlling regions, the lac operator, which is the site of action for the repressor, and the lac promoter, which is the site of initiation of transcription by RNA ' Deceased March 13. 1972. This work is dedicated to his memory.Abbreviations. /ac, thc lactose operon ; dansyl or Dns l-dimethylaniinonaphtlialene-5-sulfonyl; CNBr, cyanogcn bromide; Quadrol, N , N , N ' , N'-tetrakis(2-hydroxypropyl)ethylenediamine; cyclic AMP, adenosine 3': 5'-monophosphate. Abbreviations for amino acids follow CBN rules, see Eur. J. Biochem. 27, 201 -207 (1972). In the presence of saturating amounts of inducer the repressor-operator complex decays and a repressorinducer complex is formed which has an approximately 1000-fold lower affinity for the operator compared to free repressor [7]. The elucidation of the molecular mechanism of the repressor-operator interaction requires knowledge of the structures of repressor and operator and of its complex. Accordingly, we embarked on the task of elucidating the amino-acid sequence of repressor. The sequence of lac operator has been reported recently b...

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Section: Discussionsupporting

confidence: 81%

Section: Purification and Sequence Analysis Of The Tryptic Peptidessupporting

confidence: 75%

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Amino‐Acid Sequence of lac Repressor from Escherichia coli

Beyreuther

Adler

Fanning

et al. 1975

European Journal of Biochemistry

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“…Several recent papers have tentatively proposed models for the recognition process involving protein interactions in the small groove of DNA?6a, 31 33 These models postulate structural complementary between protein backbones in an antiparallel B-sheet conformation folded around the small groove. Other models have been proposed [34][35][36] which consider the large groove as the site of interaction . The proposed recognition in either case can only occur between the base atoms exposed in the DNA groove and amino-acid side chains.…”

Section: Resultsmentioning

confidence: 99%

Form of DNA and the nature of interactions with proteins in chromatin

Goodwin¹,

Brahms²

1978

Nucl Acids Res

112

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Studies of native chromatins and of isolated nucleosomes (from calf thymus) show that the DNA is in the B form or modified B form. This was determined by Raman spectroscopy of chromatins, of nucleosomes (from calf thymus) and of DNA fibres and directly correlated with X-ray diffraction studies. The Raman spectra of three forms of DNA (A, B and C) have been characteri zed i n fi bres btt by X-ray di ffracti on and Raman spectroscopy on the same sample. In particular, the Raman spectrum of the C form of DNA is characterized by a band of about 870 cma1. For the first time,, chromatins of different origins with increasing content of non-histone proteins have been investigated by Raman spectroscopy. The site of interaction of the non-histone proteins appears to involve the N7 position of guanine while the histone core does not interact at this site. It is proposed that the mechanism of specific recognition in chromatin involves the large groove.

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“…2͒ is understood in great detail and continues to be of great value in the study of gene regulation. 15,[18][19][20][21][22][23][24][25][26][27] LacI is a prototypic member of the large GalR-LacI family of prokaryotic transcription factors, a group that has more than 1000 members. 28 types of small signaling molecules and promotes oligomerization of the complex by protein-protein interaction between the monomers.…”

Section: Description Of the Systemmentioning

confidence: 99%

Multiple peaks and reciprocal sign epistasis in an empirically determined genotype-phenotype landscape

Dawid¹,

Kiviet²,

Kogenaru³

et al. 2010

Chaos: An Interdisciplinary Journal of Nonlinear Science

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Insight into the ruggedness of adaptive landscapes is central to understanding the mechanisms and constraints that shape the course of evolution. While empirical data on adaptive landscapes remain scarce, a handful of recent investigations have revealed genotype-phenotype and genotype-fitness landscapes that appeared smooth and single peaked. Here, we used existing in vivo measurements on lac repressor and operator mutants in Escherichia coli to reconstruct the genotype-phenotype map that details the repression value of this regulatory system as a function of two key repressor residues and four key operator base pairs. We found that this landscape is multipeaked, harboring in total 19 distinct optima. Analysis showed that all direct evolutionary pathways between peaks involve significant dips in the repression value. Consistent with earlier predictions, we found reciprocal sign epistatic interactions at the repression minimum of the most favorable paths between two peaks. These results suggest that the occurrence of multiple peaks and reciprocal epistatic interactions may be a general feature in coevolving systems like the repressor-operator pair studied here.

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How lac Repressor Binds to DNA

Cited by 231 publications

References 19 publications

Amino‐Acid Sequence of lac Repressor from Escherichia coli

Amino‐Acid Sequence of lac Repressor from Escherichia coli

Form of DNA and the nature of interactions with proteins in chromatin

Multiple peaks and reciprocal sign epistasis in an empirically determined genotype-phenotype landscape

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