Nucleotide sequences in bacteriophage f1 DNA: nucleotide sequence of genes V, VII, and VIII

Abstract

The sequence of nucleotides comprising genes V, VII, and VIII of bacteriophage fl was determined. The sequence was found to differ from that of the corresponding region of the related fd genome by eight base substitutions in gene V and one in gene VIII. The structure of gene VII was completely conserved between these two viruses and was identical to that of bacteriophage M13. Both transitions and transversions were found in cases where bases were substituted, but all substitutions were in the third codon position and had no effect on the structure of the corresponding protein product. The gene V protein product could thus be deduced to be identical to that of the corresponding proteins from bacteriophages fd and M13. A potential EcoRII cleavage site was formed by nucleotides 172 to 176 of gene V. Replicative form DNA from bacteriophage fl is normally resistant to this enzyme, and evidence is presented to suggest that the sequence was modified through methylation of cytosine 173. The probable locations of other modified nucleotides in the sequence are discussed. HapII-11 and HapII-12. The positions occupied by nucleotides in the sequence under discussion are numbered in the 5'-3' direction of the plus (sense) strand of the RFI DNA, with the "A" of the initiating ATG codon of gene V taken as nucleotide 1. The 40 on September 30, 2020 by guest http://jvi.asm.org/ Downloaded from NUCLEOTIDE SEQUENCES IN PHAGE fl DNA nucleotides identifying appropriate bands in the photographs of gel patterns have been numbered according to this convention. Nucleotides of minus-strand sequences are, however, identified on these figures by a prime. Thus, T'20 is the nucleotide complementary to A20 ofthe plus strand. (Note that the nucleotides of the minus strand are thus numbered in the 3'-) 5' direction.) We have now determined the complete sequence of the fl genome. If this sequence is numbered from the unique HindII cleavage site,,as used by Beck et al. (4) in numbering the phage fd nucleotide sequence, nucleotide 1 of the present sequence corresponds to nucleotide 843 of the total sequence. MATERIALS AND METHODS Bacteriophage fl and its host, E. coli K38, were generous gifts from N.

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