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Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins
08:14

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins

Published on: February 25, 2017

Incomplete entry of bacteriophage T7 DNA into F plasmid-containing Escherichia coli

L R García1, I J Molineux

  • 1Department of Microbiology, University of Texas, Austin 78712-1095, USA.

Journal of Bacteriology
|July 1, 1995
PubMed

Insights

Bacteriophage T7 DNA entry into E. coli is blocked by F plasmids, with only partial DNA translocation occurring. Overexpressing specific T7 genes overcomes this F-plasmid-mediated exclusion, enabling phage infection.

Area of Science:

  • Molecular Biology
  • Virology
  • Microbiology

Background:

  • Bacteriophages are viruses that infect bacteria.
  • F plasmids are conjugative plasmids in Escherichia coli that can confer resistance to phage infection.
  • Bacteriophage T7 is a well-studied model organism in molecular biology.

Purpose of the Study:

  • To investigate the mechanism of F-plasmid-mediated exclusion of bacteriophage T7 infection in Escherichia coli.
  • To identify factors involved in overcoming F-plasmid exclusion.

Main Methods:

  • Measuring Dam methylation of entering bacteriophage T7 DNA.
  • Transfecting competent E. coli cells with naked T7 DNA.
  • Overexpressing T7 1.2 alleles from plasmids or T3 1.2 from the T7 genome.

Main Results:

  • F plasmids partially inhibit bacteriophage T7 DNA penetration into E. coli.
  • The first 44% of the T7 genome enters normally, but subsequent entry is aberrant.
  • Transfecting naked DNA does not overcome F exclusion.
  • Overexpression of T7 1.2 or T3 1.2 genes allows T7 phage growth in F+ E. coli.

Conclusions:

  • F-plasmid exclusion of T7 involves a block in complete DNA translocation.
  • The T7 1.2 gene product plays a crucial role in overcoming F-plasmid-mediated inhibition of T7 infection.

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