RESUMEN
The circular, single-stranded DNA genome of the Pf3 bacteriophage was sequenced in its entirety by each of two methods, the M13-dideoxy chain termination method and the chemical degradation method. It consists of 5,833 nucleotides. With respect to both the DNA and the protein sequences, there is virtually no homology between Pf3 and the phages Ff (M13, f1, and fd) and IKe. However, similarities between these phages were noted with respect to their overall genome organizations. The gene for the single-stranded DNA-binding protein is followed by the gene for the major coat protein and then by a transcription termination signal. Open reading frames for seven other proteins were predicted, and their sizes and order show a fair correspondence to the sizes and order of the genes of the Ff phages and IKe. In addition, several regions have the potential to form stem and loop structures similar to those in the intergenic region of the Ff phage genome, but in Pf3 some are within open reading frames. Evolutionary relationships between Pf3 and the Ff phages and IKe are thus apparent through the correspondence of overall gene order rather than through primary sequence homologies.
Asunto(s)
Bacteriófagos/genética , ADN Bacteriano/genética , ADN de Cadena Simple/genética , Pseudomonas aeruginosa/genética , Secuencia de Aminoácidos , Secuencia de Bases , Codón , Genes , Genes Reguladores , Genes Virales , Enlace de Hidrógeno , Métodos , Conformación de Ácido Nucleico , Plásmidos , Proteínas Virales/genéticaRESUMEN
The region of the Pf3 virus genome encoding its major coat protein and its single-stranded DNA-binding protein is organized somewhat like the corresponding region of the fd (M13, f1) genome. Nevertheless, the major coat protein is unique among the major coat proteins of fd and the other filamentous phages studied in that it lacks a signal sequence and appears to be a direct translation product and in that it has fewer basic amino acid residues than its equivalent of DNA phosphates in the virion. These features are relevant to considerations of both protein insertion into membranes and DNA structure in filamentous viruses. The single-stranded DNA-binding protein also has a sequence that is different from the sequences of single-stranded DNA-binding proteins from other filamentous viruses.
Asunto(s)
Bacteriófagos/genética , Proteínas de Unión al ADN/genética , Genes Virales , Genes , Pseudomonas aeruginosa/genética , Proteínas del Envoltorio Viral/genética , Secuencia de Aminoácidos , Secuencia de Bases , Virión/genéticaRESUMEN
The genome of Pf3, a filamentous single-stranded DNA bacteriophage of Pseudomonas aeruginosa (a gram-negative organism) was cloned into pBD214, a plasmid cloning vector of Bacillus subtilis (a gram-positive organism). Cloning in the gram-positive organism was done to avoid anticipated lethal effects. The entire Pf3 genome was inserted in each orientation at a unique Bc/I site within a thymidylate synthetase gene (from B. subtilis phage beta 22) on the plasmid. Additional clones were made by inserting EcoRI fragments of Pf3 DNA into a unique EcoRI site within this gene.