Abstract
The N protein of bacteriophage λ is required to extend mRNA transcription beyond rho termination sites [Roberts, J. W. (1969). Nature (London) 223, 480-4821. In the absence of a functional N protein very little transcription takes place. The present study describes a unique pattern of restoration of gene expression in λN- strains by mutations in gene cro. While a λN-cro- phage does not grow on a nonpermissive Escherichia coli host, it follows the lysogenic pathway efficiently. This phage strain was found to synthesize an appreciable level of gene products of the two early λ operons as well as the cI repressor and Int protein (integrase). The experiments were conducted by infecting ultraviolet-irradiated cells with a variety of phage mutants and analyzing the synthesis of specific proteins by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis. Previous identifications of various early and late gene products were confirmed. Gene expression in the λN-cro- strains suggests a direct intimate interaction between these regulators. The results also indicate that, in the absence of N protein, transcription terminates prematurely following an exponential mode of decay. In addition, the presence of a previously hidden termination site (tL2) located within the early leftward (PL) operon is suggested.
Original language | English |
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Pages (from-to) | 405-425 |
Number of pages | 21 |
Journal | Virology |
Volume | 79 |
Issue number | 2 |
DOIs | |
State | Published - 15 Jun 1977 |