期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：32
页码：11571-11576
DOI：10.1073/pnas.0404378101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The Mo enzyme transhydroxylase from the anaerobic microorganism Pelobacter acidigallici catalyzes the conversion of pyrogallol to phloroglucinol. Such trihydroxybenzenes and their derivatives represent important building blocks of plant polymers. None of the transferred hydroxyl groups originates from water during transhydroxylation; instead a cosubstrate, such as 1,2,3,5-tetrahydroxybenzene, is used in a reaction without apparent electron transfer. Here, we report on the crystal structure of the enzyme in the reduced Mo(IV) state, which we solved by single anomalous-diffraction technique. It represents the largest structure (1,149 amino acid residues per molecule, 12 independent molecules per unit cell), which has been solved so far by single anomalous-diffraction technique. Tranhydroxylase is a heterodimer, with the active Mo-molybdopterin guanine dinucleotide (MGD)2 site in the {alpha}-subunit, and three [4Fe--4S] centers in the {beta}-subunit. The latter subunit carries a seven-stranded, mainly antiparallel {beta}-barrel domain. We propose a scheme for the transhydroxylation reaction based on 3D structures of complexes of the enzyme with various polyphenols serving either as substrate or inhibitor.
