PMID: 12595258 , Related PDB ids: 1N05, 1N06, 1N07, 1N08

Authors:

Bauer S, Kemter K, Bacher A, Huber R, Fischer M, Steinbacher S

Title:

Crystal structure of Schizosaccharomyces pombe riboflavin kinase reveals a novel ATP and riboflavin-binding fold.

Journal:

J Mol Biol. 2003 Mar 7;326(5):1463-73.

Abstract:

The essential redox cofactors riboflavin monophosphate (FMN) and flavin adenine dinucleotide (FAD) are synthesised from their precursor, riboflavin, in sequential reactions by the metal-dependent riboflavin kinase and FAD synthetase. Here, we describe the 1.6A crystal structure of the Schizosaccharomyces pombe riboflavin kinase. The enzyme represents a novel family of phosphoryl transferring enzymes. It is a monomer comprising a central beta-barrel clasped on one side by two C-terminal helices that display an L-like shape. The opposite side of the beta-barrel serves as a platform for substrate binding as demonstrated by complexes with ADP and FMN. Formation of the ATP-binding site requires significant rearrangements in a short alpha-helix as compared to the substrate free form. The diphosphate moiety of ADP is covered by the glycine-rich flap I formed from parts of this alpha-helix. In contrast, no significant changes are observed upon binding of riboflavin. The ribityl side-chain might be covered by a rather flexible flap II. The unusual metal-binding site involves, in addition to the ADP phosphates, only the strictly conserved Thr45. This may explain the preference for zinc observed in vitro.