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The biochemical basis for growth inhibition by L‐phenylalanine in Neisseria gonorrhoeae
Author(s) -
Bhatnagar R. K.,
Berry A.,
Hendry A. T.,
Jensen R. A.
Publication year - 1989
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1989.tb00188.x
Subject(s) - neisseria gonorrhoeae , biology , microbiology and biotechnology , phenylalanine , neisseria , neisseriaceae , bacteria , biochemistry , antibiotics , amino acid , genetics
Summary Clinical isolates of Neisseria gonorrhoeae are commonly subject to growth inhibition by phenylpyruvate or by L‐phenylalanine. A blockade of tyrosine biosynthesis is indicated since inhibition is reversed by either L‐tyrosine or 4‐hydroxyphenylpyruvate. Phenylalanine‐resistant (Phe R ) and phenylalanine‐sensitive (Phe s ) isolates both have a single 3‐deoxy‐D‐arabino‐heptulosonate 7‐phosphate (DAHP) synthase that is partially inhibited by L‐phenylalanine (80%). However, Phe S and Phe R isolates differ in that the ratio of phenylpyruvate aminotransferase to 4‐hydroxyphenylpyruvate aminotransferase is distinctly greater in Phe S isolates than in Phe R isolates. A mechanism for growth inhibition is proposed in which phenylalanine exerts two interactive effects, (i) Phenylalanine decreases precursor flow to 4‐hydroxyphenylpyruvate through its controlling effect upon DAHP synthase; and (ii) phenylalanine is largely transaminated to phenylpyruvate, which saturates both aminotransferases, preventing transamination of an already limited supply of 4‐hydroxyphenylpyruvate to L‐tyrosine.