Studies of the 5' exonuclease and endonuclease activities of CPSF-73 in histone pre-mRNA processing.

ABSTRACT: Processing of histone pre-mRNA requires a single 3' endonucleolytic cleavage guided by the U7 snRNP that binds downstream of the cleavage site. Following cleavage, the downstream cleavage product (DCP) is rapidly degraded in vitro by a nuclease that also depends on the U7 snRNP. Our previous studies demonstrated that the endonucleolytic cleavage is catalyzed by the cleavage/polyadenylation factor CPSF-73. Here, by using RNA substrates with different nucleotide modifications, we characterize the activity that degrades the DCP. We show that the degradation is blocked by a 2'-O-methyl nucleotide and occurs in the 5'-to-3' direction. The U7-dependent 5' exonuclease activity is processive and continues degrading the DCP substrate even after complete removal of the U7-binding site. Thus, U7 snRN

SUBMITTER: Yang XC 

PROVIDER: S-EPMC2612496 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature