MAN-MADE CELL-LIKE COMPARTMENTS FOR MOLECULAR EVOLUTION

Cellular compartmentalization is vital for the evolution of all living organisms. Cells keep together the genes, the RNAs and proteins that they encode, and the products of their activities, thus linking genoty pe to phenotype. We have reproduced this linkage in the test tube by t ranscribing and translating single genes in the aqueous compartments o f water-in-oil emulsions. These compartments, with volumes close to th ose of bacteria, can be recruited to select genes encoding catalysts. A protein or RNA with a desired catalytic activity converts a substrat e attached to the gene that encodes it to product. In other compartmen ts, substrates attached to genes that do not encode catalysts remain u nmodified. Subsequently, genes encoding catalysts are selectively enri ched by virtue of their linkage to the product. We demonstrate the lin kage of genotype to phenotype in man-made compartments using a model s ystem. A selection for target-specific DNA methylation was based on th e resistance of the product (methylated DNA) to restriction digestion. Genes encoding HaeIII methyltransferase were selected from a 10(7)-fo ld excess of genes encoding another enzyme.