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1b9i
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(New page: 200px<br /><applet load="1b9i" size="450" color="white" frame="true" align="right" spinBox="true" caption="1b9i, resolution 2.0Å" /> '''CRYSTAL STRUCTURE OF ...)
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Revision as of 21:47, 24 November 2007
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CRYSTAL STRUCTURE OF 3-AMINO-5-HYDROXYBENZOIC ACID (AHBA) SYNTHASE
Overview
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.
About this Structure
1B9I is a Single protein structure of sequence from Amycolatopsis mediterranei with PXG as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of 3-amino-5-hydroxybenzoic acid (AHBA) synthase., Eads JC, Beeby M, Scapin G, Yu TW, Floss HG, Biochemistry. 1999 Aug 3;38(31):9840-9. PMID:10433690
Page seeded by OCA on Sat Nov 24 23:54:32 2007
