Prokaryotic riboflavin biosynthesis protein
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| FAD synthetase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 crystal structure of flavin binding to fad synthetase from thermotoga maritina | |||||||||
| Identifiers | |||||||||
| Symbol | FAD_syn | ||||||||
| Pfam | PF06574 | ||||||||
| Pfam clan | CL0119 | ||||||||
| InterPro | IPR015864 | ||||||||
| SCOP2 | 1n05 / SCOPe / SUPFAM | ||||||||
| |||||||||
The prokaryotic riboflavin biosynthesis protein is a bifunctional enzyme found in bacteria that catalyzes the phosphorylation of riboflavin into flavin mononucleotide (FMN) and the adenylylation of FMN into flavin adenine dinucleotide (FAD). It consists of a C-terminal riboflavin kinase and an N-terminal FMN-adenylyltransferase. This bacterial protein is functionally similar to the monofunctional riboflavin kinases and FMN-adenylyltransferases of eukaryotic organisms, but only the riboflavin kinases are structurally homologous.
Prokaryotic riboflavin biosynthesis proteins are also known as the prokaryotic type-I FAD synthetases, which consist of a C-terminal riboflavin kinase (RFK) and an N-terminal FMN-adenylyltransferase (FMNAT). The globular RFK consists of six antiparallel β-sheets that form a β-barrel, and an α-helix adjacent to this structure. The barrel and helix are held together by 7 independent loops.[1] The FMNAT module contains an α/β dinucleotide binding domain within the active site, which it uses to bind to the substrate. The overall structure is held together by 5 parallel β-sheets that are adjacent to 4 α-helices, with 2 being long and 2 being short. A subdomain, containing 2 smaller α-helices, encompasses the area that connects to the C-terminal RFK module.[2]