The 1.4-A crystal structure of the S. pombe Pop2p deadenylase subunit unveils the configuration of an active enzyme.
Deadenylation is the first and probably also rate-limiting step of controlled mRNA decay in eukaryotes and therefore central for the overall rate of gene expression. In yeast, the process is maintained by the mega-Dalton Ccr4-Not complex, of which both the Ccr4p and Pop2p subunits are 3'-5' exonucleases potentially responsible for the deadenylation reaction. Here, we present the crystal structure of the Pop2p subunit from Schizosaccharomyces pombe determined to 1.4 A resolution and show that the enzyme is a competent ribonuclease with a tunable specificity towards poly-A. In contrast to S. cerevisiae Pop2p, the S. pombe enzyme contains a fully conserved DEDDh active site, and the high resolution allows for a detailed analysis of its configuration, including divalent metal ion binding. Functional data further indicates that the identity of the ions in the active site can modulate both activity and specificity of the enzyme, and finally structural superposition of single nucleotides and poly-A oligonucleotides provide insight into the catalytic cycle of the protein.
Jonstrup
Anette Thyssen
AT
Centre for Structural Biology, Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10c, DK-8000 Arhus C, Denmark.
Andersen
Kasper R
KR
Van
Lan B
LB
Brodersen
Ditlev E
DE
D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D005095:Exoribonucleases / Q000737:chemistry* / Q000378:metabolism; D008670:Metals / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011061:Poly A / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012260:Ribonucleases / Q000737:chemistry* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism; D040681:Structural Homology, Protein; D013379:Substrate Specificity
D008670:Metals; D021122:Protein Subunits; D029702:Schizosaccharomyces pombe Proteins; D011061:Poly A; D012313:RNA; D005095:Exoribonucleases; C520443:Pop2 protein, S pombe; D012260:Ribonucleases