Ferric uptake regulator family

Members of the ferric uptake regulator family are transcription factors that primarily exert their regulatory effects as repressors: when bound to their cognate metal ion, they are capable of binding DNA and preventing expression of the genes they regulate, but under low concentrations of metal, they undergo a conformational change that prevents DNA binding and lifts the repression. In the case of the ferric uptake regulator protein itself, its immediate downstream target is a noncoding RNA called RyhB. • Mur, responsive to manganese. • Nur, responsive to nickel. • PerR, responsive to peroxide; PerR monomers contain two binding sites and occur in zinc/iron and zinc/manganese forms. • Zur, responsive to zinc; Zur regulates uptake and transport through a regulon involving ZinT and the transporter ZnuABC. • Irr, responsive to iron through the status of heme biosynthesis. Has both activator and repressor function. Prevalent in Rhizobium, Bradyrhizobium and many other alphaproteobacteria. The iron dependent repressor family is a functionally similar but non-homologous family of proteins involved in iron homeostasis in prokaryotes. ==Relationship to virulence==

Metal homeostasis can be a factor in bacterial virulence, an observation with a particularly long history in the case of iron. In some cases, expression of virulence factors is under the regulatory control of the Fur protein. == References ==