Abstract
Numerous bacteria from different phylae can perform reactions of desulfurization of organosulfur compounds. In these degradation or detoxification pathways, the two-component flavin-dependent monooxygenases using flavin (FMN or FAD) as a cofactor play important roles as they catalyse the first steps of these metabolic routes. The TdsC or DszC and MsuC proteins belong to this class of enzymes as they process dibenzothiophene (DBT) and methanesulfinate. The elucidation of their X-ray structures in their apo, ligand, and cofactor bound forms brought important molecular insights into their catalytic reaction. Mycobacterial species were also shown to possess a DBT degradation pathway, but no structural information on this two-component flavin-dependent monooxygenases was available. In this study, we present the crystal structure of the uncharacterised MAB_4123 protein from the human pathogen Mycobacterium abscessus. The structure solved at high resolution displays high similarity with homologs from Rhodococcus, Paenibacillus and Pseudomonas species. In silico docking approaches suggest that MAB_4123 binds FMN and may use it as a cofactor. Our structural analysis strongly suggests that MAB_4123 is a two-component flavin-dependent monooxygenase that could act as a detoxifying enzyme of organosulfur compounds in mycobacteria.