title: Lrp of Corynebacterium glutamicum controls expression of the brnFE operon encoding the export system for L-methionine and branched-chain amino acids.
abstract: Corynebacterium glutamicum possesses export systems for various amino acids including BrnFE, a two-component export system for L-methionine and the branched-chain amino acids L-valine, L-isoleucine and L-leucine. A gene for a putative transcriptional regulator of the Lrp family is transcribed divergently to the brnFE operon and is required for L-isoleucine export. By comparing global gene expression changes due to L-isoleucine addition we revealed increased brnFE expression in response to L-isoleucine in C. glutamicum wild type but not in an lrp deletion mutant. ChIP-to-chip analysis, band shift experiments and DNAse footprint analysis demonstrated that Lrp binds to the intergenic region between lrp and brnF. Expression analysis of transcriptional fusions with the lrp and brnFE promoters indicated that branched-chain amino acids and L-methionine when added to the growth medium stimulated brnFE expression in the order L-leucine > L-methionine > L-isoleucine > L-valine and that Lrp was required for activation of brnFE expression. Thus, regulation of brnFE by Lrp ensures that BrnFE is synthesized only if its substrate amino acids accumulate in cells which is commensurate with its role to counteract such situations of metabolic imbalance.
authors.affiliation: Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Lange
authors.forename: Nurije
authors.initials: N
authors.lastname: Mustafi
authors.forename: Julia
authors.initials: J
authors.lastname: Frunzke
authors.forename: Nicole
authors.initials: N
authors.lastname: Kennerknecht
authors.forename: Mirja
authors.initials: M
authors.lastname: Wessel
authors.forename: Michael
authors.initials: M
authors.lastname: Bott
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D007532:Isoleucine / Q000235:genetics / Q000378:metabolism; D051756:Leucine-Responsive Regulatory Protein / Q000235:genetics* / Q000378:metabolism; D008715:Methionine / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D011401:Promoter Regions, Genetic / Q000235:genetics
chemical_list: D000597:Amino Acids, Branched-Chain; D007532:Isoleucine; D051756:Leucine-Responsive Regulatory Protein; D008715:Methionine