Biomaterial Database

The role of isochorismate hydroxymutase genes entC and menF in enterobactin and menaquinone biosynthesis in Escherichia coli. 1998

C Dahm, and R Müller, and G Schulte, and K Schmidt, and E Leistner

Institut für Pharmazeutische Biologie, Rheinische Friedrich-Wilhelms-Universität, Nussallee 6, D-53115 Bonn, Germany.

Klebsiella pneumoniae 62-1, a triple mutant impaired in aromatic amino acid biosynthesis (Phe-, Tyr-, Trp-), excretes chorismic acid into the culture broth. When transformed with plasmids harbouring Escherichia coli genes entC or menF the mutant excretes a mixture of both chorismic and isochorismic acid indicating that not only entC but also menF encodes an isochorismate hydroxymutase (isochorismate synthase, EC 5.4.99.6) enzyme. These enzymes catalyze the first step in enterobactin or menaquinone biosynthesis, respectively. Although both gene products (EntC and MenF) catalyze the same reaction, they play distinct roles in the biosynthesis of menaquinone (MK8) and enterobactin. An E. coli mutant (PBB7) with an intact menF but a disrupted entC produced menaquinone (MK8) but no enterobactin, whereas a mutant (PBB9) with an intact entC but a disrupted menF produced enterobactin and only a trace of menaquinone (MK8). When both menF and entC were disrupted (mutant PBB8) neither menaquinone (MK8) nor enterobactin was detectable. Our previous assumption that entC is responsible for both menaquinone and enterobactin biosynthesis is inconsistent with these mutant studies and has to be revised. The presence in the promoter region of menF of a putative cAMP receptor protein binding site indicates that menF is regulated differently from entC. The menF gene was overexpressed as a fusion gene and its product (6xHis-tagged MenF) isolated. The enzyme catalyzed the formation of isochorismic from chorismic acid and as opposed to a previous publication also the reverse reaction. The enzyme was characterized and its kinetic data determined.

UI	MeSH Term	Description	Entries
D007711	Klebsiella pneumoniae	Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans.	Bacillus pneumoniae,Bacterium pneumoniae crouposae,Hyalococcus pneumoniae,Klebsiella pneumoniae aerogenes,Klebsiella rhinoscleromatis
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D002827	Chorismic Acid	A cyclohexadiene carboxylic acid derived from SHIKIMIC ACID and a precursor for the biosynthesis of UBIQUINONE and the AROMATIC AMINO ACIDS.	Acid, Chorismic
D004758	Enterobactin	An iron-binding cyclic trimer of 2,3-dihydroxy-N-benzoyl-L-serine. It is produced by E COLI and other enteric bacteria.	Enterochelin
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
D014812	Vitamin K	A lipid cofactor that is required for normal blood clotting. Several forms of vitamin K have been identified: VITAMIN K 1 (phytomenadione) derived from plants, VITAMIN K 2 (menaquinone) from bacteria, and synthetic naphthoquinone provitamins, VITAMIN K 3 (menadione). Vitamin K 3 provitamins, after being alkylated in vivo, exhibit the antifibrinolytic activity of vitamin K. Green leafy vegetables, liver, cheese, butter, and egg yolk are good sources of vitamin K.
D015870	Gene Expression	The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.	Expression, Gene,Expressions, Gene,Gene Expressions
D053138	Cyclohexenes	Six-carbon alicyclic hydrocarbons which contain one or more double bonds in the ring. The cyclohexadienes are not aromatic, in contrast to BENZOQUINONES which are sometimes called 2,5-cyclohexadiene-1,4-diones.	Cyclohexadienes
D019751	Intramolecular Transferases	Enzymes of the isomerase class that catalyze the transfer of acyl-, phospho-, amino- or other groups from one position within a molecule to another. EC 5.4.	Mutases,Transferases, Intramolecular