2rbi

Publication Abstract from PubMed

Members of the microbial guanyl-specific ribonuclease family catalyse the endonucleolytic cleavage of single-stranded RNA in a two-step reaction involving transesterification to form a 2',3'-cyclic phosphate and its subsequent hydrolysis to yield the respective 3'-phosphate. The extracellular ribonuclease from Bacillus intermedius (binase, RNase Bi) shares a common mechanism for RNA hydrolysis with mammalian RNases. Two catalytic residues in the active site of binase, Glu72 and His101, are thought to be involved in general acid-general base catalysis of RNA cleavage. Using site-directed mutagenesis, binase mutants were produced containing amino acid substitutions H101N and H101T and their catalytic properties towards RNA, poly(I), poly(A), GpC and guanosine 2',3'-cyclic phosphate (cGMP) substrates were studied. The engineered mutant proteins are active in the transesterification step which produces the 2',3'-cyclic phosphate species but they have lost the ability to catalyse hydrolysis of the cyclic phosphate to give the 3' monophosphate product.

RNA cleavage without hydrolysis. Splitting the catalytic activities of binase with Asn101 and Thr101 mutations.,Okorokov AL, Panov KI, Offen WA, Mukhortov VG, Antson AA, Karpeisky MYa, Wilkinson AJ, Dodson GG Protein Eng. 1997 Mar;10(3):273-8. PMID:9153077^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.