Sequence and Regulatory Signals of the Filamentous Phage Genome

Abstract

The genome of the male-specific filamentous coliphages fd, f1, and M13 is a circular single-stranded DNA of approximately 6400 bases, which codes for at least eight genes (Marvin and Hohn 1969; Ray 1977). Upon infecting a cell, a double-stranded replicative-form (RF) DNA is formed, and this RF DNA then serves as a template for mRNA synthesis as well as for progeny phage DNA production. Both reactions are catalyzed and controlled largely by host proteins. Therefore, the structure and function of the filamentous phage DNA have been studied extensively as a model system for elucidating the molecular mechanisms involved in DNA replication and gene expression.

The first nucleotide sequences of filamentous phage DNA to be determined were the pyrimidine tracts obtained by the Burton and Peterson depurination procedure; tracts of up to 20 bases in length were sequenced (Petersen and Reeves 1969; Ling 1972). Oligonucleotide-primed DNA synthesis was used by Oertel and Schaller (1972) to determine the order of pyrimidine tracts in a pyrimidine-rich segment of fd DNA (positions 5539–5630, Fig. 1) and, in combination with ribosubstitution, by Sanger et al. (1973 Sanger et al. (1974) to deduce the sequence of 85 nucleotides in f1 DNA (positions 6303–6387, Fig. 1).

Three ribosome-binding sites on DNA-directed mRNA were sequenced by Pieczenik et al. (1974). Ribosomes bind specifically to the start point of translation on mRNA, and the bound region can be isolated and sequenced after RNase treatment. Similar protection experiments with RNA polymerase allowed the isolation and sequencing of an RNA-polymerase-binding site from...