A thermostable D-polymerase for mirror-image PCR

Biological evolution resulted in a homochiral world in which nucleic acids consist exclusively of D-nucleotides and proteins made by ribosomal translation of L-amino acids. From the perspective of synthetic biology, however, particularly anabolic enzymes that could build the mirror-image counterparts of biological macromolecules such as L-DNA or L-RNA are lacking. Based on a convergent synthesis strategy, we have chemically produced and characterized a thermostable mirror-image polymerase that efficiently replicates and amplifies mirror-image (L)-DNA. This artificial enzyme, dubbed D-Dpo4-3C, is a mutant of Sulfolobus solfataricus DNA polymerase IV consisting of 352 D-amino acids. D-Dpo4-3C was reliably deployed in classical polymerase chain reactions (PCR) and it was used to assemble a first mirror-image gene coding for the protein Sso7d. We believe that this D-polymerase provides a valuable tool to further investigate the mysteries of biological (homo) chirality and to pave the way for potential novel life forms running on a mirror-image genome.