Structural Diversity and Specificities within the Ferredoxin‐Disulfide/Thioredoxin Reductase Family

Abstract

Abstract Ferredoxin–thioredoxin reductases (FTRs) and ferredoxin–disulfide reductases (FDRs) are relatively small enzymes that reduce the disulfide bond of redoxins. While most oxygenic photosynthetic organisms possess FTRs, FDRs are found in a variety of nonphotosynthetic prokaryotes. The catalytic center consists of a [4Fe‐4S] cluster and a redox‐active disulfide. FTRs are heterodimers formed by a catalytic subunit associated with a variable subunit. The latter is not present in FDRs. Instead, in some microorganisms, FDRs are fused to additional domains, notably rubredoxin or thioredoxin/glutaredoxin, which donate or accept electrons, respectively. This article reviews the state of the art in the structure–function relationships for this family of enzymes, describing their occurrence, catalytic mechanism, structural properties, and outstanding issues.