3g10
Structure of S. pombe Pop2p - Mg2+ and Mn2+ bound form
Structural highlights
FunctionCAF1_SCHPO Acts as the catalytic component of the CCR4-NOT core complex, which in the nucleus seems to be a general transcription factor, and in the cytoplasm the major mRNA deadenylase involved in mRNA turnover. In vivo and in vitro, caf1 has 3'-exoribonuclease activity with a preference for poly(A) RNAs.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIn eukaryotic organisms, initiation of mRNA turnover is controlled by progressive shortening of the poly-A tail, a process involving the mega-Dalton Ccr4-Not complex and its two associated 3'-5' exonucleases, Ccr4p and Pop2p (Caf1p). RNA degradation by the 3'-5' DEDDh exonuclease, Pop2p, is governed by the classical two metal ion mechanism traditionally assumed to be dependent on Mg(2+) ions bound in the active site. Here, we show biochemically and structurally that fission yeast (Schizosaccharomyces pombe) Pop2p prefers Mn(2+) and Zn(2+) over Mg(2+) at the concentrations of the ions found inside cells and that the identity of the ions in the active site affects the activity of the enzyme. Ion replacement experiments further suggest that mRNA deadenylation could be subtly regulated by local Zn(2+) levels in the cell. Finally, we use site-directed mutagenesis to propose a mechanistic model for the basis of the preference for poly-A sequences exhibited by the Pop2p-type deadenylases as well as their distributive enzymatic behavior. The activity and selectivity of fission yeast Pop2p are affected by a high affinity for Zn2+ and Mn2+ in the active site.,Andersen KR, Jonstrup AT, Van LB, Brodersen DE RNA. 2009 May;15(5):850-61. Epub 2009 Mar 23. PMID:19307292[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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