Characterization of a key trifunctional enzyme for aromatic amino acid biosynthesis in Archaeoglobus fulgidus

In the aromatic amino acid biosynthesis pathway, chorismate presents a branch point intermediate that is converted to tryptophan, phenylalanine (Phe), and tyrosine (Tyr). In bacteria, three enzymes catalyze the conversion of chorismate to hydroxyphenylpyruvate or pyruvate. The enzymes, chorismate mu...

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Vydané v:	Extremophiles : life under extreme conditions Ročník 13; číslo 1; s. 191 - 198
Hlavní autori:	Lim, Sierin, Springstead, James R, Yu, Marcella, Bartkowski, Wojciech, Schröder, Imke, Monbouquette, Harold G
Médium:	Journal Article
Jazyk:	English
Vydavateľské údaje:	Japan Japan : Springer Japan 2009 Springer Japan Springer Springer Nature B.V
Predmet:	Amino acids Amino Acids, Aromatic - biosynthesis Archaeoglobus fulgidus Archaeoglobus fulgidus - enzymology Archaeoglobus fulgidus - genetics Bacteria Bacteriology Base Sequence Biochemistry Biological and medical sciences Biomedical and Life Sciences Biosynthesis Biotechnology Chromatography, Liquid DNA Primers E coli Electrophoresis, Polyacrylamide Gel Enzymes Escherichia coli Fundamental and applied biological sciences. Psychology Kinetics Life Sciences Mass Spectrometry Metabolism. Enzymes Metabolites Microbial Ecology Microbiology Nanoarchaeum equitans Original Paper Phylogeny Polymerase Chain Reaction Proteins Thermodynamics Evolution Aromatic amino acid biosynthesis Chorismate mutase Prephenate dehydratase Prephenate dehydrogenase Archaea Archaeoglobus Archaeobacteria Enzyme Archaeoglobus fulgidus Lyases Biosynthesis Characterization Isomerases Gene Aminoacid Intramolecular transferases Bacteria Aromatic compound Oxidoreductases Molecular cloning Carbon-oxygen lyases Extreme environment Hydro-lyases
ISSN:	1431-0651, 1433-4909, 1433-4909
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Shrnutí:	In the aromatic amino acid biosynthesis pathway, chorismate presents a branch point intermediate that is converted to tryptophan, phenylalanine (Phe), and tyrosine (Tyr). In bacteria, three enzymes catalyze the conversion of chorismate to hydroxyphenylpyruvate or pyruvate. The enzymes, chorismate mutase (CM), prephenate dehydratase (PDT), and prephenate dehydrogenase (PDHG) are either present as distinct proteins or fusions combining two activities. Gene locus AF0227 of Archaeoglobus fulgidus is predicted to encode a fusion protein, AroQ, containing all three enzymatic domains. This work describes the first characterization of a trifunctional AroQ. The A. fulgidus aroQ gene was cloned and overexpressed in Escherichia coli. The recombinant protein purified as a homohexamer with specific activities of 10, 0.51, and 50 U/mg for CM, PDT, and PDHG, respectively. Tyr at 0.5 mM concentration inhibited PDHG activity by 50%, while at 1 mM PDT was activated by 70%. Phe at 5 μM inhibited PDT activity by 66% without affecting the activity of PDHG. A fusion of CM, PDT, and PDHG domains is evident in the genome of only one other organism sequenced to date, that of the hyperthermophilic archaeon, Nanoarchaeum equitans. Such fusions of contiguous activities in a biosynthetic pathway may constitute a primitive strategy for the efficient processing of labile metabolites.
Bibliografia:	http://dx.doi.org/10.1007/s00792-008-0209-z ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 ObjectType-Article-2 ObjectType-Feature-1 content type line 23
ISSN:	1431-0651 1433-4909 1433-4909
DOI:	10.1007/s00792-008-0209-z