Crystal structure of the flavoprotein ArsH from Sinorhizobium meliloti

Purified ArsH from Sinorhizobium meliloti exhibits NADPH:FMN-dependent reduction of molecular O-2 to hydrogen peroxide and catalyzes reduction of azo dyes. The structure of ArsH was determined at 1.8 angstrom resolution. ArsH crystallizes with eight molecules in the asymmetric unit forming two tetramers. Each monomer has a core domain with a central five-stranded parallel P-sheet and two monomers interact to form a classical flavodoxin-like dimer. The N- and C-terminal extensions of ArsH are involved in interactions between subunits and tetramer formation. The structure may provide insight in how ArsH participates in arsenic detoxification. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.