5ux0
From Proteopedia
X-ray crystal structure of Marinitoga piezophila Argonaute in complex with 5' OH guide RNA and target DNA
Structural highlights
FunctionAGO_MARPK An RNA-guided ssDNA endonuclease that may play a role in defense against invading mobile genetic elements. Uses short 5'-OH-ssRNA sequences as guides (gRNA) to bind complementary target DNA (tDNA) or target RNA resulting in target cleavage. The cleavage site is 10 nucleotides (nt) downstream of the target residue base-paired with the 5'-end of the gRNA. Reaction rates are fastest on 5'-OH-gRNA:tDNA followed by 5'-OH-gRNA:target RNA. gRNA between 17-21 nt supports equivalent rates of cleavage, has no preferred 5'-nt. Has weak activity on tDNA with 5'-phospho-gRNA, yielding products 1-2 nt longer (PubMed:27035975). Unlike other characterized prokaryotic Ago proteins symmetric mismatches centered around the cleavage site reduce cleavage efficiency (PubMed:28520746).[1] [2] Publication Abstract from PubMedArgonaute (Ago) proteins are widespread in prokaryotes and eukaryotes and share a four-domain architecture capable of RNA- or DNA-guided nucleic acid recognition. Previous studies identified a prokaryotic Argonaute protein from the eubacterium Marinitoga piezophila (MpAgo), which binds preferentially to 5'-hydroxylated guide RNAs and cleaves single-stranded RNA (ssRNA) and DNA (ssDNA) targets. Here we present a 3.2 A resolution crystal structure of MpAgo bound to a 21-nucleotide RNA guide and a complementary 21-nucleotide ssDNA substrate. Comparison of this ternary complex to other target-bound Argonaute structures reveals a unique orientation of the N-terminal domain, resulting in a straight helical axis of the entire RNA-DNA heteroduplex through the central cleft of the protein. Additionally, mismatches introduced into the heteroduplex reduce MpAgo cleavage efficiency with a symmetric profile centered around the middle of the helix. This pattern differs from the canonical mismatch tolerance of other Argonautes, which display decreased cleavage efficiency for substrates bearing sequence mismatches to the 5' region of the guide strand. This structural analysis of MpAgo bound to a hybrid helix advances our understanding of the diversity of target recognition mechanisms by Argonaute proteins. DNA recognition by an RNA-guided bacterial Argonaute.,Doxzen KW, Doudna JA PLoS One. 2017 May 17;12(5):e0177097. doi: 10.1371/journal.pone.0177097., eCollection 2017. PMID:28520746[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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