Allosteric Regulation of the Third Ribonucleotide Reductase (NrdEF Enzyme) from Enterobacteriaceae

摘要: Enterobacteriaceae contain genes for three separate ribonucleotide reductases: nrdAB code a class Ia enzyme, active during aerobiosis, nrdDG III anaerobiosis, and nrdEF cryptic Ib enzyme. The NrdEF enzyme provides the reductase in other, widely different bacteria. Here, we describe allosteric regulation of Salmonella typhimurium It consists two tightly bound homodimeric proteins, R1E R2F. Nucleoside triphosphates (ATP, dATP, dGTP, dTTP) regulate substrate specificity by binding to single site protein (one nucleotide per polypeptide). Regulation is similar that NrdAB with one major exception: dATP stimulates reduction CDP (and UDP) under conditions when strongly inhibits all activity nrdA-coded R1 contains second ATP) controls general activity. All known proteins lack 50 N-terminal amino acids R1, propose located this area protein. more sophisticated enzymes eukaryotes protection against possibly harmful overproduction dNTPs.