1B9H

CRYSTAL STRUCTURE OF 3-AMINO-5-HYDROXYBENZOIC ACID (AHBA) SYNTHASE

Summary for 1B9H

• Entry DOI: 10.2210/pdb1b9h/pdb
• Descriptor: PROTEIN (3-AMINO-5-HYDROXYBENZOIC ACID SYNTHASE), PYRIDOXAL-5'-PHOSPHATE (3 entities in total)
• Functional Keywords: rifamycin biosynthesis (rifd gene)
• Biological source: Amycolatopsis mediterranei
• Total number of polymer chains: 1
• Total formula weight: 42509.77

Authors

Eads, J.C.,Beeby, M.,Scapin, G.,Yu, T.-W.,Floss, H.G. (deposition date: 1999-02-11, release date: 1999-08-13, Last modification date: 2023-12-27)

Primary citation

Eads, J.C.,Beeby, M.,Scapin, G.,Yu, T.W.,Floss, H.G.
Crystal structure of 3-amino-5-hydroxybenzoic acid (AHBA) synthase.
Biochemistry, 38:9840-9849, 1999

PubMed Abstract: The biosynthesis of ansamycin antibiotics, including rifamycin B, involves the synthesis of an aromatic precursor, 3-amino-5-hydroxybenzoic acid (AHBA), which serves as starter for the assembly of the antibiotics' polyketide backbone. The terminal enzyme of AHBA formation, AHBA synthase, is a dimeric, pyridoxal 5'-phosphate (PLP) dependent enzyme with pronounced sequence homology to a number of PLP enzymes involved in the biosynthesis of antibiotic sugar moieties. The structure of AHBA synthase from Amycolatopsis mediterranei has been determined to 2.0 A resolution, with bound cofactor, PLP, and in a complex with PLP and an inhibitor (gabaculine). The overall fold of AHBA synthase is similar to that of the aspartate aminotransferase family of PLP-dependent enzymes, with a large domain containing a seven-stranded beta-sheet surrounded by alpha-helices and a smaller domain consisting of a four-stranded antiparallel beta-sheet and four alpha-helices. The uninhibited form of the enzyme shows the cofactor covalently linked to Lys188 in an internal aldimine linkage. On binding the inhibitor, gabaculine, the internal aldimine linkage is broken, and a covalent bond is observed between the cofactor and inhibitor. The active site is composed of residues from two subunits of AHBA synthase, indicating that AHBA synthase is active as a dimer.

PubMed: 10433690
DOI: 10.1021/bi990018q

Experimental method

X-RAY DIFFRACTION (2 Å)