Bacteriophage T4 gol site: sequence analysis and effects of the site on plasmid transformation.

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RESUMO

The Escherichia coli lit gene product is required for the multiplication of bacteriophage T4 at temperatures below 34 degrees C. After infection of a lit mutant host, early gene product synthesis is normal, as is T4 DNA replication; however, the late gene products never appear, and early gene product synthesis eventually ceases. Consequently, at late times, there is no protein synthesis of any kind (W. Cooley, K. Sirotkin, R. Green, and L. Snyder, J. Bacteriol. 140:83-91, 1979; W. Champness and L. Snyder, J. Mol. Biol. 155:395-407, 1982), and no phage are produced. We have isolated T4 mutants which can multiply in lit mutant hosts. The responsible T4 mutations (called gol mutations) completely overcome the block to T4 gene expression (Cooley et al., J. Bacteriol. 140:83-91). We have proposed that gol mutations alter a cis-acting regulatory site on T4 DNA rather than a diffusible gene product and that the wild-type form of the gol site (gol+) somehow interferes with gene expression late in infection (Champness and Snyder, J. Mol. Biol. 155:395-409). In this communication, we report the sequence of the gol region of the T4 genome from five different gol mutants. The gol mutations are all single-base-pair transitions within 40 base pairs of DNA. Therefore, the gol site is at least 40 base pairs long. The sequence data confirm that the gol phenotype is not due to an altered protein. We also report that the gol+ site in plasmids prevents transformation of Lit- but not Lit+ E. coli. Thus, the gol site is at least partially active in the absence of the T4 genome.

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