Replication of X174 DNA: In Vitro Synthesis of X RFI DNA and Circular, Single-stranded DNA

Abstract

The complexity of DNA replication in Escherichia coli can be readily appreciated from the isolation of a large number of point mutations on the chromosome, which affect DNA synthesis (Wechsler and Gross 1971; Gross 1972; Wickner 1978). These mutations have been divided into two categories: those concerned with initiation and those involved in elongation. At present, the gene products or loci involved in initiation (and/or termination) include dnaA, dnaC, dnaI, dnaP, and RNA polymerase (specifically, the β subunit, the subunit governing rifampicin sensitivity) (Wechsler 1978). The gene products involved in elongation of DNA chains include dnaB, dnaG, dnaZ, dnaE (polC) lig (DNA ligase), polAex (the 5′→3′ exonuclease of DNA polymerase I), cou (novobiocin target protein), nalA, (the nalidixic acid target protein), and in part rep. The products resulting from four additional mutations (dnaJ, dnaK, dnaL, and dnaM) remain to be characterized (Wickner 1978). The number of gene products listed above...