PMID:11506923

Citation	Jossek, R, Bongaerts, J and Sprenger, GA (2001) Characterization of a new feedback-resistant 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase AroF of Escherichia coli. FEMS Microbiol. Lett. 202:145-8
Abstract	Tyrosine feedback-inhibits the 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase isoenzyme AroF of Escherichia coli. Here we show that an Asn-8 to Lys-8 substitution in AroF leads to a tyrosine-insensitive DAHP synthase. This mutant enzyme exhibited similar activities (v=30-40 U mg(-1)) and substrate affinities (K(m)(erythrose-4-phosphate)=0.5 mM, positive cooperativity with respect to phospho(enol)pyruvate) as the wild-type AroF, but showed decreased thermostability. An engineered AroF enzyme lacking the seven N-terminal residues also was tyrosine-resistant. These results strongly suggest that the N-terminus of AroF is involved in the molecular interactions occurring in the feedback-inhibition mechanism.
Links	PubMed
Keywords	3-Deoxy-7-Phosphoheptulonate Synthase/chemistry; 3-Deoxy-7-Phosphoheptulonate Synthase/genetics; 3-Deoxy-7-Phosphoheptulonate Synthase/metabolism; Alleles; Amino Acid Sequence; Amino Acid Substitution/genetics; Enzyme Stability; Escherichia coli/enzymology; Escherichia coli/genetics; Feedback, Physiological/drug effects; Kinetics; Mutation/genetics; Sequence Homology, Amino Acid; Sugar Phosphates/metabolism; Temperature; Tyrosine/metabolism; Tyrosine/pharmacology
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