title: How do haloarchaea synthesize aromatic amino acids?
abstract: Genomic analysis of H. salinarum indicated that the de novo pathway for aromatic amino acid (AroAA) biosynthesis does not follow the classical pathway but begins from non-classical precursors, as is the case for M. jannaschii. The first two steps in the pathway were predicted to be carried out by genes OE1472F and OE1475F, while the 3rd step follows the canonical pathway involving gene OE1477R. The functions of these genes and their products were tested by biochemical and genetic methods. In this study, we provide evidence that supports the role of proteins OE1472F and OE1475F catalyzing consecutive enzymatic reactions leading to the production of 3-dehydroquinate (DHQ), after which AroAA production proceeds via the canonical pathway starting with the formation of DHS (dehydroshikimate), catalyzed by the product of ORF OE1477R. Nutritional requirements and AroAA uptake studies of the mutants gave results that were consistent with the proposed roles of these ORFs in AroAA biosynthesis. DNA microarray data indicated that the 13 genes of the canonical pathway appear to be utilised for AroAA biosynthesis in H. salinarum, as they are differentially expressed when cells are grown in medium lacking AroAA.
authors.affiliation: Department of Membrane Biochemistry, Max-Planck-Institute of Biochemistry, Martinsried, Germany.
authors.forename: Miriam Kolog
authors.initials: MK
authors.lastname: Gulko
authors.affiliation: School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, Australia.
authors.forename: Mike
authors.initials: M
authors.lastname: Dyall-Smith
authors.affiliation: Teaching and Research Unit Bioinformatics, Institut of Informatik Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Orland
authors.initials: O
authors.lastname: Gonzalez
authors.affiliation: Department of Membrane Biochemistry, Max-Planck-Institute of Biochemistry, Martinsried, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
mesh_terms: D024322:Amino Acids, Aromatic / Q000096:biosynthesis* / Q000235:genetics; D001105:Archaea / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D020745:Genome, Archaeal; D053858:Metabolic Networks and Pathways / Q000235:genetics
chemical_list: D024322:Amino Acids, Aromatic; D019843:Archaeal Proteins