The LipB protein is a negative regulator of dam gene expression in Escherichia coli

TY - JOUR

T1 - The LipB protein is a negative regulator of dam gene expression in Escherichia coli

AU - Vaisvila, R

AU - Rasmussen, L J

AU - Lobner-Olesen, A

AU - von Freiesleben, U

AU - Marinus, M G

PY - 2000/11/15

Y1 - 2000/11/15

N2 - Transcription initiation of the major promoter (P2) of the Escherichia coli dam gene increases with growth rate. The presence of three partially palindromic motifs, (TTCAGT(N(20))TGAG), designated G (growth)-boxes, within the -52 to +31 region of the promoter, may be related to growth rate control. Deletion of two of these repeats, downstream of the transcription initiation point, result in constitutive high activity of the promoter. The unlinked cde-4::miniTn10 insertion also results in severalfold higher activity of the dam P2 promoter, suggesting that this mutation resulted in the loss of a putative dam P2 repressor. The cde-4 mutation was mapped to the lipB (lipoic acid) gene, which we show encodes a 24 kDa protein initiating at a TTG codon. LipB is a highly conserved protein in animal and plant species, other bacteria, Archaea, and yeast. Plasmids expressing the native or hexahistidine-tagged LipB complement the phenotype of the cde-4 mutant strain. The level of LipB in vivo was higher in exponentially growing cells than those in the stationary phase. Three G-box motifs were also found in the lipB region. Models for the regulation of expression of the two genes are discussed.

AB - Transcription initiation of the major promoter (P2) of the Escherichia coli dam gene increases with growth rate. The presence of three partially palindromic motifs, (TTCAGT(N(20))TGAG), designated G (growth)-boxes, within the -52 to +31 region of the promoter, may be related to growth rate control. Deletion of two of these repeats, downstream of the transcription initiation point, result in constitutive high activity of the promoter. The unlinked cde-4::miniTn10 insertion also results in severalfold higher activity of the dam P2 promoter, suggesting that this mutation resulted in the loss of a putative dam P2 repressor. The cde-4 mutation was mapped to the lipB (lipoic acid) gene, which we show encodes a 24 kDa protein initiating at a TTG codon. LipB is a highly conserved protein in animal and plant species, other bacteria, Archaea, and yeast. Plasmids expressing the native or hexahistidine-tagged LipB complement the phenotype of the cde-4 mutant strain. The level of LipB in vivo was higher in exponentially growing cells than those in the stationary phase. Three G-box motifs were also found in the lipB region. Models for the regulation of expression of the two genes are discussed.

KW - Amino Acid Sequence

KW - Bacterial Proteins/chemistry

KW - Base Sequence

KW - Blotting, Western

KW - Cell Division

KW - Codon, Initiator/genetics

KW - Escherichia coli/genetics

KW - Gene Expression Regulation, Bacterial

KW - Genetic Complementation Test

KW - Molecular Sequence Data

KW - Mutation/genetics

KW - Operon/genetics

KW - Promoter Regions, Genetic/genetics

KW - Recombinant Fusion Proteins/isolation & purification

KW - Response Elements/genetics

KW - Sequence Alignment

M3 - Journal article

C2 - 11072067

SN - 0304-419X

VL - 1494

SP - 43

EP - 53

JO - Biochimica et Biophysica Acta - Reviews on Cancer

JF - Biochimica et Biophysica Acta - Reviews on Cancer

IS - 1-2

ER -