Biomaterial Database

Chromosomal organization and expression of Escherichia coli pabA. 1990

P V Tran, and T A Bannor, and S Z Doktor, and B P Nichols

Department of Biological Sciences, University of Illinois, Chicago 60680.

The pabA gene in Escherichia coli and Salmonella typhimurium encodes the glutamine amidotransferase subunit of para-aminobenzoate synthase, which catalyzes the first reaction in the conversion of chorismate to para-aminobenzoate (PABA). We have determined the nucleotide sequences of 1,362 base pairs preceding E. coli pabA and of 981 base pairs preceding S. typhimurium pabA. The nucleotide sequences suggest the presence of two protein-coding regions immediately upstream of pabA, designated orf1 and fic. Transcription analysis indicates that E. coli pabA is encoded by two overlapping transcriptional units. The polycistronic transcriptional unit includes orf1-fic-pabA and is initiated by the promoter designated P2. The monocistronic unit includes only pabA and is initiated by the promoter designated P1, which is located in the fic-coding region. Both promoters transcribe pabA to about the same steady-state level. However, expression analysis using chromosomal pabA-lacZ translational fusions indicated that P1 expressed PabA at least 50-fold more efficiently than P2. pabA-dependent growth rate analysis indicates that P1 is essential and P2 is dispensable for PABA metabolism. In the absence of P1, growth was reduced as a result of insufficient PabA expressed from P2. The significance of these results and possible posttranscriptional control mechanisms which affect PabA expression from the P2-initiated polycistronic unit are discussed.

UI	MeSH Term	Description	Entries
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
D010129	4-Aminobenzoic Acid	An aminobenzoic acid isomer that combines with pteridine and GLUTAMIC ACID to form FOLIC ACID. The fact that 4-aminobenzoic acid absorbs light throughout the UVB range has also resulted in its use as an ingredient in SUNSCREENS.	PABA,p-Aminobenzoic Acid,para-Aminobenzoic Acid,4-Aminobenzoic Acid, Potassium Salt,Aminobenzoic Acid (USP),Epit Vit,Epitelplast,Hachemina,Magnesium para-Aminobenzoate,Pabasan,Paraminan,Paraminol,Potaba,Potassium 4-Aminobenzoate,Potassium Aminobenzoate,4 Aminobenzoic Acid,4 Aminobenzoic Acid, Potassium Salt,4-Aminobenzoate, Potassium,Aminobenzoate, Potassium,Potassium 4 Aminobenzoate,p Aminobenzoic Acid,para Aminobenzoic Acid,para-Aminobenzoate, Magnesium
D011401	Promoter Regions, Genetic	DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.	rRNA Promoter,Early Promoters, Genetic,Late Promoters, Genetic,Middle Promoters, Genetic,Promoter Regions,Promoter, Genetic,Promotor Regions,Promotor, Genetic,Pseudopromoter, Genetic,Early Promoter, Genetic,Genetic Late Promoter,Genetic Middle Promoters,Genetic Promoter,Genetic Promoter Region,Genetic Promoter Regions,Genetic Promoters,Genetic Promotor,Genetic Promotors,Genetic Pseudopromoter,Genetic Pseudopromoters,Late Promoter, Genetic,Middle Promoter, Genetic,Promoter Region,Promoter Region, Genetic,Promoter, Genetic Early,Promoter, rRNA,Promoters, Genetic,Promoters, Genetic Middle,Promoters, rRNA,Promotor Region,Promotors, Genetic,Pseudopromoters, Genetic,Region, Genetic Promoter,Region, Promoter,Region, Promotor,Regions, Genetic Promoter,Regions, Promoter,Regions, Promotor,rRNA Promoters
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
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
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
D000637	Transaminases	A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.	Aminotransferase,Aminotransferases,Transaminase
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D014158	Transcription, Genetic	The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.	Genetic Transcription