The Structure of a Truncated Phosphoribosylanthranilate Isomerase Suggests a Unified Model for Evolution of the (βα)8 Barrel Fold

The (βα)8 barrel is one of the most common protein folds, and enzymes with this architecture display a remarkable range of catalytic activities. Many of these functions are associated with ancient metabolic pathways, and phylogenetic reconstructions suggest that the (βα)8 barrel was one of the very first protein folds to emerge. Consequently, there is considerable interest in understanding the evolutionary processes that gave rise to this fold....