Enzymological basis for growth inhibition by L-phenylalanine in the cyanobacterium Synechocystis sp. 29108.

Journal of Bacteriology
G Hall, R A Jensen

Abstract

The pattern of allosteric control in the biosynthetic pathway for aromatic amino acids provides a basis to explain vulnerability to growth inhibition by l-phenylalanine (0.2 mM or greater) in the unicellular cyanobacterium Synechocystis sp. 29108. We attribute growth inhibition to the hypersensitivity of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase to feedback inhibition by l-phenylalanine. Hyperregulation of this initial enzyme of aromatic biosynthesis depletes the supply of precursors needed for biosynthesis of l-tyrosine and l-tryptophan. Consistent with this mechanism is the total reversal of phenylalanine inhibition by a combination of tyrosine and tryptophan. Inhibited cultures also contained decreased levels of phycocyanin pigments, a characteristic previously correlated with amino acid starvation in cyanobacteria. l-Phenylalanine is a potent noncompetitive inhibitor (with both substrates) of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase, whereas l-tyrosine is a very weak inhibitor. Prephenate dehydratase also displays allosteric sensitivity to phenylalanine (inhibition) and to tyrosine (activation). Both 2-fluoro and 4-fluoro derivatives of phenylalanine were potent analog antimetabolites, and these were us...Continue Reading

References

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Citations

Mar 1, 1989·Molecular Microbiology·R K BhatnagarR A Jensen
Sep 1, 1990·World Journal of Microbiology & Biotechnology·D Kumar
Nov 18, 2018·Phytochemistry·Ronald StebeggAnnette Rompel
May 1, 1983·Journal of Bacteriology·M J FiskeR A Jensen
Apr 25, 1989·Biochimica Et Biophysica Acta·T H Xia, J S Chiao
Oct 16, 2021·Journal of Agricultural and Food Chemistry·Haojie JinYujie Fu

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