Single-strand binding protein enhances fidelity of DNA synthesis in vitro.

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Abstract
The effect of Escherichia coli single-strand binding protein on the accuracy of in vitro DNA synthesis was determined using 2 independent methods. Using the synthetic polynucleotide poly[d(A-T)] and measuring dGTP misincorporation or by using [phage] .vphi.X174 DNA and measuring nucleotide substitutions showed that binding protein increases the fidelity of DNA synthesis by as much as 10-fold. This increase is observed with DNA polymerases of divergent sources and is progressive with increasing concentration of binding protein. The increased accuracy observed with DNA polymerases lacking a 3'' .fwdarw. 5'' exonuclease points to a mechanism other than augmented proofreading. In accord with the properties of single-strand binding proteins, it is suggested that increased fidelity is a result of enhanced base selection by the DNA polymerase, resulting from increased rigidity of the template due to its interaction with binding protein.