French scientists have synthesised borono-analogues of nucleotides that form di-nucleotides through a borate ester bond rather than the phosphate linkage found in their natural counterparts. This finding opens the possibility of boron playing a role in pre-biotic chemistry or could form the basis of an artificial genetic code, claim the authors. 

The team led by Jean-Jacques Vasseur and Michael Smietana at University of Montpellier 2, France, synthesised the borono-nucleotides from the respective 5'-aldehydic nucleoside through a homologation/reduction sequence. The boron was added by borylation or cross-metathesis. Replacing the phosphate linkages with boron allows the reversible non-enzymatic assembly of these compounds with ribonucleotide partners forming a new reversible linkage between two nucleotides. 

The abundance of boron and its presence in hydrothermal vents offers the possibility that it played a role in pre-biotic chemistry. Researchers believe that 'some other molecules must have preceded RNA and have started looking for a pre-RNA world where elementary building blocks were polymerised through a chemical process,' says Smietana. 

Using structural studies, the team demonstrate that the borono-analogues are close mimics of their natural counterparts. The application of these borononucleotides isn't limited to studying pre-biotic chemistry as the authors suggest they could also form the basis of an artificial genetic system.