The emergence of catalysis in early genetic polymers such as RNA is considered a key transition in the origin of life1, pre-dating the appearance of protein enzymes. DNA also demonstrates the capacity to fold into three-dimensional structures and form catalysts in vitro2. However, to what degree these natural biopolymers comprise functionally privileged chemical scaffolds3 for folding or the evolution of catalysis is not known. The ability of synthetic genetic polymers (XNAs) with alternative backbone chemistries not found in nature to fold into defined structures and bind ligands4 raises the possibility that these too might be capable of forming catalysts (XNAzymes). Here we report the discovery of such XNAzymes, elaborated in four different chemistries (arabino nucleic acids, ANA5; 2′-fluoroarabino nucleic acids, FANA6; hexitol nucleic acids, HNA; and cyclohexene nucleic acids, CeNA7) directly from random XNA oligomer pools, exhibiting in trans RNA endonuclease and ligase activities. We also describe an XNA–XNA ligase metalloenzyme in the FANA framework, establishing catalysis in an entirely synthetic system and enabling the synthesis of FANA oligomers and an active RNA endonuclease FANAzyme from its constituent parts. These results extend catalysis beyond biopolymers and establish technologies for the discovery of catalysts in a wide range of polymer scaffolds not found in nature8. Evolution of catalysis independent of any natural polymer has implications for the definition of chemical boundary conditions for the emergence of life on Earth and elsewhere in the Universe9.

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This work was supported by the Medical Research Council (MRC) programme grant U105178804 (P. Holliger, A.I.T., V.B.P., A.S.M., S.P.-C., C.C.) and by grants from the European Science Foundation (ESF) and the Biotechnology and Biological Sciences Research Council (BBSRC) UK (09-EuroSYNBIO-OP-013) (P.H., A.I.T.), the European Union Framework (FP7/2007-2013 (P. Herdewijn), the European Research Council (ERC-2012 ADG_20120216/320683 (P. Herdewijn)), the US National Science Foundation (MCB-1121024 (K.M.W.)) and by an NSF Graduate Research Fellowship (DGE-1144081 (M.J.S.)).

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Author notes

    • Vitor B. Pinheiro

    Present address: Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK, and Structural and Molecular Biology Department, University College London, Gower Street, London WC1E 6BT, UK.


  1. MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK

    • Alexander I. Taylor
    • , Vitor B. Pinheiro
    • , Alexey S. Morgunov
    • , Sew Peak-Chew
    • , Christopher Cozens
    •  & Philipp Holliger
  2. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA

    • Matthew J. Smola
    •  & Kevin M. Weeks
  3. KU Leuven, Rega Institute, Minderbroedersstraat 10, B 3000 Leuven, Belgium

    • Piet Herdewijn
  4. Université Evry, Institute of Systems and Synthetic Biology, 5 rue Henri Desbruères, 91030 Evry Cedex, France

    • Piet Herdewijn


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A.I.T. and P. Holliger conceived and designed the experiments. A.I.T. performed XNAzyme selections and characterized XNAzymes with V.B.P., A.S.M., S.P.-C., C.C. V.B.P. generated the improved HNA synthetase. M.J.S. and K.M.W. performed and analysed SHAPE and DMS mapping experiments. P. Herdewijn synthesized hNTPs, ceNTPs and aGTP. All authors analysed data and co-wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Philipp Holliger.

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