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Host RecJ is required for growth of P22 erf bacteriophage
M J Mahan1, A Garzón, J Casadesús
1Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Abstract:
Growth of bacteriophage P22 erf is known to require host RecA recombination function. We show that the RecA function is necessary but not sufficient to restore the plaque-forming ability of phage P22 erf; such mutant phage also requires host RecJ function. The residual efficiency of plaquing of P22 erf in a recJ background (0.03%) is completely abolished in recJ recB hosts (< 0.001%), suggesting that the RecBCD nuclease can provide an alternative function allowing phage growth. One tentative explanation is that circularization of P22 erf DNA mostly proceeds through the RecF pathway of recombination; however, less efficient circularization via the RecBCD pathway may also occur. In a recJ background, lysates obtained upon induction of an erf prophage show reduced yield (10%), suggesting that growth of P22 erf may require host RecJ in a step(s) other than circularization of phage DNA.
Insights
Bacteriophage P22 erf growth requires host RecA and RecJ functions. The RecBCD nuclease can partially substitute for RecJ, indicating complex host-pathogen interactions in phage DNA repair and replication.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacteriophage P22 erf growth is known to depend on host RecA recombination function.
- Understanding the specific host factors involved in phage replication is crucial for deciphering viral life cycles.
Purpose of the Study:
- To investigate the complete host genetic requirements for bacteriophage P22 erf plaque formation.
- To elucidate the roles of host RecJ and RecBCD in P22 erf growth.
Main Methods:
- Comparative analysis of P22 erf plaque-forming ability in various host mutant backgrounds (recA, recJ, recJ recB).
- Assessing phage yield upon prophage induction in different host strains.
Main Results:
- RecA function is necessary but insufficient for P22 erf plaque formation; RecJ function is also required.
- Residual plaquing efficiency in recJ mutants is abolished in recJ recB hosts, indicating a role for RecBCD.
- Reduced phage yield in recJ hosts suggests RecJ's involvement in steps beyond DNA circularization.
Conclusions:
- Bacteriophage P22 erf requires both RecA and RecJ host functions for efficient growth.
- The RecBCD nuclease can partially compensate for the lack of RecJ, possibly through an alternative DNA circularization pathway.
- Host RecJ plays a role in P22 erf growth independent of DNA circularization, highlighting complex host-pathogen interactions.