A Trp199Glu MauG variant reveals a role for Trp199 interactions with pre-methylamine dehydrogenase during tryptophan tryptophylquinone biosynthesis

•A W199E MauG mutation alters hydrogen bonding interactions with preMADH.•A W199E MauG mutation alters the kinetic mechanism of interprotein electron transfer.•Trp199 of MauG plays multiple roles in MauG-catalyzed TTQ biosynthesis.

MauG catalyzes posttranslational modifications of a methylamine dehydrogenase precursor (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Trp199 is present at the site of interaction between MauG and preMADH and is critical to this process as it mediates hole hopping during the inter-protein electron transfer that is required for catalysis. Trp199 was converted to Glu and the structure and reactivity of the W199E/preMADH complex were characterized. The results reveal that the nature of residue 199 is also important for productive complex formation between preMADH and MauG.

Structured summary of protein interactionspreMADH light chain, preMADH heavy chain and MauGphysically interact by X-ray crystallography (View interaction).