Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein.
Argonaute (Ago) proteins in eukaryotes are known as key players in post-transcriptional gene silencing1, while recent studies on prokaryotic Agos hint at their role in the protection against invading DNA2,3. Here, we present crystal structures of the apo enzyme and a binary Ago-guide complex of the archaeal Methanocaldococcus jannaschii (Mj) Ago. Binding of a guide DNA leads to large structural rearrangements. This includes the structural transformation of a hinge region containing a switch helix, which has been shown for human Ago2 to be critical for the dynamic target search process4-6. To identify key residues crucial for MjAgo function, we analysed the effect of several MjAgo mutants. We observe that the nature of the 3' and 5' nucleotides in particular, as well as the switch helix, appear to impact MjAgo cleavage activity. In summary, we provide insights into the molecular mechanisms that drive DNA-guided DNA silencing by an archaeal Ago.
Institute of Microbiology, University of Regensburg, 93053 Regensburg, Germany.
Sarah
S
Willkomm
Center for Integrated Protein Science Munich CIPSM, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
Christine A
CA
Oellig
Institute of Microbiology, University of Regensburg, 93053 Regensburg, Germany.
Adrian
A
Zander
Institute for Molecular Medicine, University of Lübeck, 23538 Lübeck, Germany.
Tobias
T
Restle
CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK.|Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
Ronan
R
Keegan
Institute of Microbiology, University of Regensburg, 93053 Regensburg, Germany.
Dina
D
Grohmann
Center for Integrated Protein Science Munich CIPSM, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
Sabine
S
Schneider
D060565:Argonaute Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019641:DNA, Archaeal / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D063747:Methanocaldococcus / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D034622:RNA Interference
C466422:AGO2 protein, human; D060565:Argonaute Proteins; D019641:DNA, Archaeal