title: Structural basis for RNA trimming by RNase T in stable RNA 3'-end maturation.
abstract: RNA maturation relies on various exonucleases to remove nucleotides successively from the 5' or 3' end of nucleic acids. However, little is known regarding the molecular basis for substrate and cleavage preference of exonucleases. Our biochemical and structural analyses on RNase T-DNA complexes show that the RNase T dimer has an ideal architecture for binding a duplex with a short 3' overhang to produce a digestion product of a duplex with a 2-nucleotide (nt) or 1-nt 3' overhang, depending on the composition of the last base pair in the duplex. A 'C-filter' in RNase T screens out the nucleic acids with 3'-terminal cytosines for hydrolysis by inducing a disruptive conformational change at the active site. Our results reveal the general principles and the working mechanism for the final trimming step made by RNase T in the maturation of stable RNA and pave the way for the understanding of other DEDD family exonucleases.
authors.affiliation: Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Yu-Yuan
authors.initials: YY
authors.lastname: Hsiao
authors.forename: Che-Chuan
authors.initials: CC
authors.lastname: Yang
authors.forename: Chia Liang
authors.initials: CL
authors.lastname: Lin
authors.forename: Jason L J
authors.initials: JL
authors.lastname: Lin
authors.forename: Yulander
authors.initials: Y
authors.lastname: Duh
authors.forename: Hanna S
authors.initials: HS
authors.lastname: Yuan
mesh_terms: D020413:3' Untranslated Regions; D001483:Base Sequence; D020134:Catalytic Domain; D003596:Cytosine / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005092:Exonucleases / Q000378:metabolism; D005095:Exoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D020413:3' Untranslated Regions; D012313:RNA; D003596:Cytosine; D005092:Exonucleases; D005095:Exoribonucleases; C042081:exoribonuclease T