Self- -replication as a tool in molecular evolution
model bottom half


Polynucleotide polymerases occupy a central role in the maintenance, transmission and expression of genetic information [1]. Indeed, the ability to replicate nucleic acid templates is a prerequisite for evolution itself [2]. Polymerases have also enabled core technologies of molecular biology like sequencing, PCR, site-directed mutagenesis and cDNA cloning. However, polymerases available from nature are often not optimally suited for these applications. Despite recent advances in our understanding of polymerase function our ability to engineer polymerases for specific applications has been limited.









We describe CSR (compartmentalised self-replication), a strategy for the directed evolution of enzymes, especially polymerases [3]. CSR is based on a simple feedback loop consisting of a polymerase that replicates only its own encoding gene (1). Compartmentation serves to isolate the individual self-replication reactions from each other (2). In such a system adaptive gains directly (and proportionally) translate into genetic amplification of the encoding gene.
Structure of the closed ternary
complex of Taq polymerase.
(from Li et al (1998) EMBO J., 17, 7514)



Structure of the closed ternary complex of Taq polymerase


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