Nucleotide sequence of gene VII and of a hypothetical gene (IX) in bacteriophage M13.

A DNA fragment containing gene VII of bacteriophage M13 has been transcribed and the nucleotide sequence of this 169-nucleotides long transcript was determined by RNA sequencing methods. Additionally, the nucleotide sequence of this gene and parts of its neighbouring genes V and VIII has been determined by the dimethylsulphate-hydrazine technique. The reading frame of gene VII has been established by determining the nucleotide changes occurring in the transcripts of two amber mutants of this gene. From these combined data it is apparent that gene VII is only 99 nucleotides long and is immediately followed by the termination codon UGA. Its initiation codon AUG is separated from gene V by only a single nucleotide. It was noted that between the UGA termination codon of gene VII and the initiation codon of the next gene (gene VIII) there is space for another, hitherto unknown gene. This gene (IX) most probably codes for the small polypeptide ("C-protein") present in mature M13 phage particles.