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The Crystal Structure of RosB: Insights into the Reaction Mechanism of the First Member of a Family of Flavodoxin‐like Enzymes
Author(s) -
Konjik Valentino,
Brünle Steffen,
Demmer Ulrike,
Vanselow Amanda,
Sandhoff Roger,
Ermler Ulrich,
Mack Matthias
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201610292
Subject(s) - flavodoxin , flavoprotein , chemistry , stereochemistry , enzyme , active site , cofactor , reaction intermediate , substituent , substrate (aquarium) , atp synthase , biochemistry , biology , catalysis , ferredoxin , ecology
8‐demethyl‐8‐aminoriboflavin‐5′‐phosphate (AFP) synthase (RosB) catalyzes the key reaction of roseoflavin biosynthesis by forming AFP from riboflavin‐5′‐phosphate (RP) and glutamate via the intermediates 8‐demethyl‐8‐formylriboflavin‐5′‐phosphate (OHC‐RP) and 8‐demethyl‐8‐carboxylriboflavin‐5′‐phosphate (HO 2 C‐RP). To understand this reaction in which a methyl substituent of an aromatic ring is replaced by an amine we structurally characterized RosB in complex with OHC‐RP (2.0 Å) and AFP (1.7 Å). RosB is composed of four flavodoxin‐like subunits which have been upgraded with specific extensions and a unique C‐terminal arm. It appears that RosB has evolved from an electron‐ or hydride‐transferring flavoprotein to a sophisticated multi‐step enzyme which uses RP as a substrate (and not as a cofactor). Structure‐based active site analysis was complemented by mutational and isotope‐based mass‐spectrometric data to propose an enzymatic mechanism on an atomic basis.