Prof. Phil Holliger

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

Abstract

Synthetic biology seeks to probe fundamental aspects of biological form and function by construction (i.e. resynthesis) rather than deconstruction (analysis). Synthesis thus complements analytic studies, and allows novel approaches towards fundamental biological questions.

We have been exploiting the synthesis paradigm to explore the chemical etiology of the genetic apparatus shared by all life on earth, specifically the synthesis, reverse transcription and replication of novel synthetic genetic polymers (xeno nucleic acids: XNAs) based on nucleic acid architectures not found in nature and show that these too can mediate genetic information storage and propagation [1, 2].

Beyond heredity, we demonstrate a capacity for Darwinian evolution by the in vitro evolution of ligands (XNA aptamers) and catalysts (XNAzymes) [2, 3] including XNAs with uncharged P-alkyl-phosphonate backbones, which challenge the polyelectrolyte paradigm for genetic polymers [4]. Thus, heredity and evolution, two central hallmarks of living systems, are not limited to DNA and RNA, but can be implemented in synthetic polymers.

I’ll also describe our progress in the engineering and evolution of RNA polymerase ribozymes towards self-replication. We have discovered RNA polymerase ribozymes that are capable of the templated synthesis (i.e. transcription) of another ribozyme [5] or themselves from triplet building blocks. This RNA triplet polymerase ribozyme enables replication of even highly structured RNA templates as well as non-canonical reverse and primer-free as well as rolling circle RNA replication modes [6, 7].

[1] Pinheiro VB, Taylor AI, Cozens C, Abramov M, Renders M, Zhang S, Chaput JC, Wengel J, Peak-Chew S-Y, McLaughlin SH, Herdewijn P & Holliger P (2012) Synthetic Genetic Polymers Capable of Heredity and Evolution. Science, 336: 341-44.

[2] Taylor AI, Pinheiro VB, Smola MJ, Morgunov AS, Peak-Chew SY, Cozens C, Weeks KM, Herdewijn P & Holliger P. (2015) Catalysts from synthetic genetic polymers. Nature, 518: 427-30

[3]  Taylor AI, Wan CJK, Donde MJ, Peak-Chew SY & Holliger P (2022) A modular XNAzyme cleaves long, structured RNAs under physiological conditions and enables allele-specific gene silencing.  Nature Chemistry, 14: 1295-1305

[4] Arangundy-Franklin S, Taylor AI, Porebski BT, Genna V, Peak-Chew S, Vaisman A, Woodgate R, Orozco M & Holliger P. (2019) A synthetic genetic polymer with an uncharged backbone chemistry based on alkyl phosphonate nucleic acids. Nature Chemistry, 11: 533-42

[5] Wochner A,  Attwater J,  Coulson A & Holliger P  (2011) Ribozyme-catalyzed transcription of an active ribozyme. Science,  332 : 209-12.

[6] Attwater J, Raguram A, Morgunov AS, Gianni E & Holliger P (2018) Ribozyme-catalysed RNA synthesis using triplet building blocks. eLife, 7:e35255

[7] Kristoffersen EL, Burman M, Noy A & Holliger P. (2022) Rolling circle RNA synthesis catalyzed by RNA.  eLife,  11 : e75186.