title: Characterization of Lrp, and Escherichia coli regulatory protein that mediates a global response to leucine.
abstract: Exogenous leucine affects the expression of a number of different operons in Escherichia coli. For at least some of these operons, the leucine-related effect is mediated by a protein called Lrp (Leucine-responsive regulatory protein). The purification of Lrp to near homogeneity is described. Lrp is a moderately abundant, basic protein composed of two subunits of molecular mass 18.8 kDa each. In addition, the corresponding protein was purified from a strain having a mutation within the gene that encodes Lrp (lrp). This mutation (lrp-1) causes high constitutive expression of ilvIH, one of the operons controlled by Lrp (Platko, J. V., Willins, D.A., and Calvo, J.M. (1990) J. Bacteriol. 172, 4563-4570). The Lrp-1 and Lrp proteins have similar physical properties, but they show some differences in the characteristics with which they bind DNA upstream of the ilvIH promoter. The nucleotide sequences of the lrp and lrp-1 genes differ by only a single nucleotide, a C to G change that would substitute a Glu for an Asp at amino acid 114. Lrp has some amino acid sequence similarity to AsnC, a protein that regulates asnA expression (Kolling, R., and Lother, H. (1985) J. Bacteriol. 164, 310-315).
authors.affiliation: Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
authors.forename: D A
authors.initials: DA
authors.lastname: Willins
authors.forename: C W
authors.initials: CW
authors.lastname: Ryan
authors.forename: J V
authors.initials: JV
authors.lastname: Platko
authors.forename: J M
authors.initials: JM
authors.lastname: Calvo
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D007930:Leucine / Q000494:pharmacology*; D051756:Leucine-Responsive Regulatory Protein; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D009876:Operon / Q000187:drug effects*; D016133:Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; C497280:Lrp-1 protein, E coli; D015345:Oligonucleotide Probes; D014157:Transcription Factors; D051756:Leucine-Responsive Regulatory Protein; D007930:Leucine