3-Amino-4-hydroxybenzoic acid

3-Amino-4-hydroxybenzoic acid production from sweet sorghum juice by recombinant Corynebacterium glutamicum.[Pubmed:26409852]

Bioresour Technol. 2015 Dec;198:410-7.

The production of the bioplastic precursor 3-Amino-4-hydroxybenzoic acid (3,4-AHBA) from sweet sorghum juice, which contains amino acids and the fermentable sugars sucrose, glucose and fructose, was assessed to address the limitations of producing bio-based chemicals from renewable feedstocks. Recombinant Corynebacterium glutamicum strain KT01 expressing griH and griI derived from Streptomyces griseus produced 3,4-AHBA from the sweet sorghum juice of cultivar SIL-05 at a final concentration (1.0 g l(-1)) that was 5-fold higher than that from pure sucrose. Fractionation of sweet sorghum juice by nanofiltration (NF) membrane separation (molecular weight cut-off 150) revealed that the NF-concentrated fraction, which contained the highest concentrations of amino acids, increased 3,4-AHBA production, whereas the NF-filtrated fraction inhibited 3,4-AHBA biosynthesis. Amino acid supplementation experiments revealed that leucine specifically enhanced 3,4-AHBA production by strain KT01. Taken together, these results suggest that sweet sorghum juice is a potentially suitable feedstock for 3,4-AHBA production by recombinant C. glutamicum.

Novel benzene ring biosynthesis from C(3) and C(4) primary metabolites by two enzymes.[Pubmed:17003031]

J Biol Chem. 2006 Dec 1;281(48):36944-51.

The shikimate pathway, including seven enzymatic steps for production of chorismate via shikimate from phosphoenolpyruvate and erythrose-4-phosphate, is common in various organisms for the biosynthesis of not only aromatic amino acids but also most biogenic benzene derivatives. 3-Amino-4-hydroxybenzoic acid (3,4-AHBA) is a benzene derivative serving as a precursor for several secondary metabolites produced by Streptomyces, including grixazone produced by Streptomyces griseus. Our study on the biosynthesis pathway of grixazone led to identification of the biosynthesis pathway of 3,4-AHBA from two primary metabolites. Two genes, griI and griH, within the grixazone biosynthesis gene cluster were found to be responsible for the biosynthesis of 3,4-AHBA; the two genes conferred the in vivo production of 3,4-AHBA even on Escherichia coli. In vitro analysis showed that GriI catalyzed aldol condensation between two primary metabolites, l-aspartate-4-semialdehyde and dihydroxyacetone phosphate, to form a 7-carbon product, 2-amino-4,5-dihydroxy-6-one-heptanoic acid-7-phosphate, which was subsequently converted to 3,4-AHBA by GriH. The latter reaction required Mn(2+) ion but not any cofactors involved in reduction or oxidation. This pathway is independent of the shikimate pathway, representing a novel, simple enzyme system responsible for the synthesis of a benzene ring from the C(3) and C(4) primary metabolites.

Interaction of mushroom tyrosinase with aromatic amines, o-diamines and o-aminophenols.[Pubmed:15279888]

Biochim Biophys Acta. 2004 Aug 4;1673(3):170-7.

3-Amino-L-tyrosine was found to be a substrate of mushroom tyrosinase, contrary to what had previously been reported in the literature. A series of amino derivatives of benzoic acid were tested as substrates and inhibitors of the enzyme. 3-Amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid and 3,4-diaminobenzoic acid were oxidized by this enzyme, as previously reported for Neurospora crassa tyrosinase, but 4-aminobenzoic acid and 3-aminobenzoic acid were not. Interestingly, 3-Amino-4-hydroxybenzoic acid was oxidized five times faster than 4-amino-3-hydroxybenzoic acid, confirming the importance of proton transfer from the hydroxyl group at C-4 position. All compounds inhibited the monophenolase activity but their effect on the diphenolase activity was small or negligible. 3-Amino-4-hydroxybenzoic acid was a stronger inhibitor than 4-amino-3-hydroxybenzoic acid, indicating their different binding affinity to the oxy form of the enzyme. Both, however, were weaker inhibitors than 3-amino-L-tyrosine, 4-methoxy-o-phenylenediamine and 3,4-diaminobenzoic acid, which was the strongest inhibitor from among the compounds tested. These results show that the relative positioning of the amino group and the hydroxy group in o-aminophenols with respect to the side chain is important both for binding to the dicopper center and for catalysis.