Biomaterial Database

Identification of high affinity binding sites for LexA which define new DNA damage-inducible genes in Escherichia coli. 1994

L K Lewis, and G R Harlow, and L A Gregg-Jolly, and D W Mount

Laboratory of Molecular Genetics, National Institutes of Health, NIEHS Research Triangle Park, NC 27709.

A multi-step screening procedure was devised to identify new operators for the LexA repressor in the sequenced portions of the genomes of Escherichia coli and its plasmids and bacteriophages. Sequence analysis methods were employed initially to distinguish true LexA operators from "operator-like" sequences stored within the GenBank and EMBL databases. The affinity of purified LexA protein for cloned DNA fragments containing several of the prospective new sites was then assessed using quantitative electrophoretic mobility shift assays and site-directed mutagenesis. Calculated binding affinities were compared directly with values determined for known and mutant LexA operators in concurrent experiments. Three E. coli chromosomal segments (near pyrC, hsdS and ntrla) and two bacteriophage sequences (near the P1 cre and lambda oop genes) bound LexA protein specifically. These sites and most others identified in the screening are located immediately upstream of known genes and/or large open reading frames. These results and additional transcription data demonstrate that several of the sequences define new DNA damage-inducible (din) genes and include the previously uncharacterized dinD locus. Furthermore, the search identified an SOS gene within the genome of P1 which encodes a protein that is homologous to UmuD', the RecA-promoted cleavage product of the umuD gene. The success of the combinatorial approach described here suggests that analogous searches for new regulatory sequences within the E. coli genome and the genomes of other organisms will also yield favorable results.

UI	MeSH Term	Description	Entries
D008957	Models, Genetic	Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Genetic Models,Genetic Model,Model, Genetic
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009875	Operator Regions, Genetic	The regulatory elements of an OPERON to which activators or repressors bind thereby effecting the transcription of GENES in the operon.	Operator Region,Operator Regions,Operator, Genetic,Genetic Operator,Genetic Operator Region,Genetic Operator Regions,Genetic Operators,Operator Region, Genetic,Operators, Genetic,Region, Genetic Operator,Region, Operator,Regions, Genetic Operator,Regions, Operator
D012097	Repressor Proteins	Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.	Repressor Molecules,Transcriptional Silencing Factors,Proteins, Repressor,Silencing Factors, Transcriptional
D002876	Chromosomes, Bacterial	Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.	Bacterial Chromosome,Bacterial Chromosomes,Chromosome, Bacterial
D003090	Coliphages	Viruses whose host is Escherichia coli.	Escherichia coli Phages,Coliphage,Escherichia coli Phage,Phage, Escherichia coli,Phages, Escherichia coli
D004268	DNA-Binding Proteins	Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.	DNA Helix Destabilizing Proteins,DNA-Binding Protein,Single-Stranded DNA Binding Proteins,DNA Binding Protein,DNA Single-Stranded Binding Protein,SS DNA BP,Single-Stranded DNA-Binding Protein,Binding Protein, DNA,DNA Binding Proteins,DNA Single Stranded Binding Protein,DNA-Binding Protein, Single-Stranded,Protein, DNA-Binding,Single Stranded DNA Binding Protein,Single Stranded DNA Binding Proteins
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial