Evolution of the RNA Coliphages: The Role of Secondary Structures during RNA Replication

Abstract

The process of RNA-directed RNA synthesis is central to the survival of the RNA bacteriophages (Loeb and Zinder 1961). Despite their apparent simplicity, these infectious agents have evolved a highly sophisticated mechanism of propagation that obviates the need for a DNA intermediate (Cooper and Zinder 1962; Doi and Spiegelman 1962; Haywood and Sinsheimer 1963). The phage RNA provides a dual function during lytic infection. Upon entering a host, it serves as a poly-cistronic messenger RNA (Ohtaka and Spiegelman 1963), directing translation of phage-specific proteins. Later, the same RNA serves as a template for its own replication by a phage-induced RNA-directed RNA replicase (Haruna and Spiegelman 1965a). Using the single-stranded viral RNA as template, the RNA replicase synthesizes a single-stranded, antiparallel complement (Spiegelman et al. 1969; Weissmann et al. 1969). This complementary RNA, in turn, serves as a template for the production of new single-stranded phage RNA molecules (Feix et al....