Probing the catalytic triad of an archaeal RNA splicing endonuclease.

ABSTRACT: Among the four known mechanisms of intron removal, three are reputedly catalyzed by RNA molecules. In the fourth mechanism, a protein endonuclease removes introns from nuclear tRNA and all archaeal RNAs. Three strictly conserved residues of the splicing endonuclease, a histidine, a lysine, and a tyrosine, were predicted to catalyze the intron cleavage reaction in a manner similar to that of the catalytic triad of ribonuclease A. Single-turnover kinetic parameters were obtained for the wild-type enzyme and two triad mutants. Mutation of histidine to alanine produced an at least approximately 28-fold reduction; mutation of tyrosine to phenylalanine produced an at least approximately 7-fold reduction in activity, while a histidine and tyrosine double mutation abolished cleavage. The single mu

SUBMITTER: Calvin K 

PROVIDER: S-EPMC6296462 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature