Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PRP16 is an RNA-dependent ATPase that is required for the second catalytic step of pre-mRNA splicing. We have previously shown that PRP16 protein binds stably to spliceosomes that have completed 5' splice site cleavage and lariat formation. PRP16 then promotes 3' splice site cleavage and exon ligation in an ATP-dependent fashion. We now demonstrate that PRP16 can hydrolyse all nucleoside triphosphates and corresponding deoxynucleotides; complementation of the second catalytic step shows the same broad nucleotide specificity. These results link the nucleotide requirement of step 2 to PRP16. Interestingly, we find that PRP16 promotes a conformational change in the spliceosome which results in the protection of the 3' splice site against oligo-directed RNase H cleavage. This structural rearrangement is dependent on the hydrolysis of ATP, since ATP gamma S, a competitive inhibitor of the PRP16 ATPase activity, does not promote the protection of the 3' splice site and formation of mRNA.
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PMID:A conformational rearrangement in the spliceosome is dependent on PRP16 and ATP hydrolysis. 146 25

U1 small nuclear RNA plays an important role in early stages of intron recognition and spliceosome assembly. The 5' splice site of the premessenger RNA base-pairs with the 5' end of U1; however, that interaction appears to be replaced by U5 and U6 at later stages of the splicing process. It has not been established when this transition occurs nor what factors are required for the transition. The PRP2 gene of Saccharomyces cerevisiae encodes an RNA-dependent ATPase that belongs to the DEAH putative RNA helicase family. A spliceosome can be assembled in the absence of PRP2 but the ATPase activity of PRP2 is required for the onset of the catalytic reactions in the spliceosome. By probing the precatalytic spliceosome formed in temperature-sensitive prp2 mutant extracts with oligonucleotides complementary to snRNAs, we found that the 5' end of U1 was sensitive to RNase H digestion whereas the 5' splice site-interacting region of U6 became resistant. Furthermore, by treating with heparin, a spliceosome depleted of U1 snRNA was isolated that subsequently underwent splicing with additional protein factors and ATP. Thus, these results indicate that PRP2 is not responsible for the transition from U1 to U6 in the spliceosome and that the entire U1 snRNA is not involved in the catalytic phase of pre-mRNA splicing.
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PMID:Analysis of small nuclear RNAs in a precatalytic spliceosome. 883 38