Abstract
The gene 32 protein of the bacteriophage T4 plays an important role in genetic recombination, DNA repair, and DNA replication; the protein functions in these processes by virtue of a strong binding capacity for single-stranded DNA. During infections of Escherichia coli by bacteriophage carrying amber of temperature-sensitive mutations in gene 32, the altered gene 32 protein (that is, the amber fragment of the missense polypeptide) is synthesized at greatly elevated rates. During infections by phages that are mutant in other genes (and wild type in gene 32), gene 32 expression is coupled to the quantity of single-stranded DNA produced during the infection. The data are consistent with a model in which the gene 32 protein binds preferentially to all available single-stranded DNA. When all available single-stranded DNA is complexed with gene 32 protein, free gene 32 protein represses its own synthesis. The high level expression of altered gene 32 proteins (amber fragments or missense polypeptides) is a direct consequence of the proposed autoregulation.
Highlights
T4 plays an important role in genetic recombination, DNA repair, and DNA replication; the protein functions in these processes by virtue of a strong binding capacity for single-stranded
The gene 32 protein is an essential function of the bacteriophage T4, required both for DNA synthesis and genetic rc:ombination
The data are expressed as a ratio of “P32” to P32 synthesis; the rate of P32 synthesis is obtained from the control (i.e. 45-32+) infection. (In the 45-32+ infection, the absolute rate of P32 synthesis diminishes by a factor of 2 during the course of the experiment)
Summary
Bacteriophage Strains-Mutants were generously provided as follows: temperature-sensitive gene 32 mutants from Bruce Alberta, amber gene 32 mutants from Bruce Alberts Mixed “C-amino-acids were used to label proteins under the conditions described in the legends. All figures of gels are autoradiograms prepared as described previously [8]. The peaks have not been normalized to amino acid incorporation; equal quantities of infected cells were electrophoresed and quantified for each experiment. The molecular weights of the three protein fragments produced by infection with amber mutations in gene 32 were determined from a comparison of their mobilities with that of the wild type gene 32 protein and other specific T4 proteins whose molecular weights have been determined [8]. Data for “P32” expression during gene 32 amber mutant infections have been corrected for the molecular weight difference between the fragment and wild type P32 (35,000 [3, 4]).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
