title: A new isochorismate synthase specifically involved in menaquinone (vitamin K2) biosynthesis encoded by the menF gene.
abstract: A new gene (menF) encoding an isochorismate synthase specifically involved in menaquinone (vitamin K2) biosynthesis has been cloned and sequenced. Overexpression of the encoded polypeptide under the influence of a T7 promoter showed an increase in specific activity of 2200-fold. Treatment with protamine sulfate resulted in another 3.5-fold increase in specific activity (7700-fold compared to the parent strain). The relative molecular mass of the overexpressed protein was M(r) 49 000, which is in full agreement with the DNA sequence predicted molecular mass of 48 777 Da. Purified enzyme converted chorismate to isochorismate with the product of the reaction shown to be isochorismate by its thermal conversion to salicylic acid. The fluorescence spectrum generated by the formed salicylic acid was identical to that of authentic salicylic acid. The 5' end of the flanking menD gene has also be redefined.
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb 60115-2861, USA.
authors.forename: R
authors.initials: R
authors.lastname: Daruwala
authors.forename: O
authors.initials: O
authors.lastname: Kwon
authors.forename: R
authors.initials: R
authors.lastname: Meganathan
authors.forename: M E
authors.initials: ME
authors.lastname: Hudspeth
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002827:Chorismic Acid / Q000378:metabolism; D003001:Cloning, Molecular; D053138:Cyclohexenes; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D005798:Genes, Bacterial; D019751:Intramolecular Transferases; D007535:Isomerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014812:Vitamin K / Q000096:biosynthesis*
chemical_list: D053138:Cyclohexenes; D004269:DNA, Bacterial; D014812:Vitamin K; C052985:isochorismic acid; D007535:Isomerases; D019751:Intramolecular Transferases; C058486:isochorismate synthase; D002827:Chorismic Acid