Rossmann-fold motifs can confer multiple functions to metabolic enzymes: RNA binding and ribonuclease activity of a UDP-glucose dehydrogenase

► A UDP-glucose dehydrogenase (UgdG) from Sphingomonas elodea exhibits ribonucleolytic activity. ► The Rossmann fold motifs of UgdG are capable of serving as a RNA-binding domain. ► The UgdG Rossmann fold motifs share structural features with mitochondrial ribonucleases named MAR. ► The Rossmannoid fold may represent the prototype of an ancient ribonuclease.