Flavodoxin fold
From Wikipedia, the free encyclopedia
The flavodoxin fold is a common structural motif, α/β protein fold, second only to the TIM barrel fold. It has three layers, with two α-helical layers sandwiching a 5-stranded parallel β-sheet. The order of strands within the sheet is 2-1-3-4-5. The Flavodoxin fold is found in many proteins in different organisms like algae, fungi, plants and mammals. This specific structural fold is important to researchers because it is commonly found in proteins among many different organisms.
The flavodoxin fold has been proposed to be one of the earliest protein folds, emerging as the sixth fold, in some models, during the evolution of protein architectures.[1] This fold is evolutionary ancient but is now absent from most eukaryotes. The fold can still be found in the proteins of human biological system like Cytochrome P450 reductase and Nitric oxide synthase. It can also be found bacteria and viruses.[2]
Flavodoxin protein
Flavodoxin is the origin protein from which the motif derives its name from. Flavodoxin is a type of protein that is created when there is a lack of iron presence and then it replaces the proteins that contain iron.[3] It is made up of α helices and β-strands. The β-strands are connected by either a loop or an α helix.[4] The FLD gene codes for the Flavodoxin protein and can either be short chained or long chained with the long chain having approximately 20 residues in a loop. Gram positive bacteria only contain short chain Flavodoxins. Cyanobacteria and algae most commonly contain the long chain Flavodoxin.[1] Flavodoxins contain a singular Flavin mononucleotide, also known as FMN.[3]
