Slonomics: An Advanced Technology for Automated Gene Synthesis

For current gene synthesis protocols, usually a set of individually designed single-stranded oligonucleotides is first constructed using automated solid-phase synthesisers. Then the oligonucleotides are purified and subsequently assembled using specific annealing and standard ligation or polymerase reactions. To improve specificity of oligonucleotide annealing, the synthesis step relies on a set of thermostable DNA ligase and polymerase enzymes. Despite many improvements to the basic technology (1), which was originally developed in 1972, oligonucleotide accuracy is still a central issue for de novo gene synthesis. The result of a gene synthesis experiment is largely dependent on the quality of the oligonucleotides used. If 95% of the molecules in the oligonucleotide mix are correct (that is, as designed), and 5% are incorrect (for example, due to incomplete coupling or base modification during de-protection), a typical end-product with 30 assembled molecules has a probability of 0.95 (21.5%) of having the correct sequence. Oligos longer than 40 nucleotides, which are preferred for gene synthesis applications, are increasingly susceptible to errors during the chemical synthesis process.