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Growth of single-stranded DNA phages in replication mutants of Escherichia coli
Abstract:
Host capacity for growth of single-stranded DNA phages was investigated with several replication mutants of E. coli. In dnaL708, dnam709 and dnaS707 mutants, multiplication of phiK was not restricted even at 42 degree C. In dnaM710 cells, however, growth of phiK was severely effected at 42 degree C but not at 33 degree C. Upon infection of phiK, parental replicative form was synthesized at the restrictive temperature, whereas subsequent step (replication of progeny replicative form) was blocked in the dnaZ strain. Growth of phiX174 and alpha3, as tested by transfection, was also thermosensitive in the dnaM710 mutant but not in the dnaL708, dnaM709 and dnaS707 strains. In contrast with lambda, microvirid phages could grow in E. coli cells bearing the groPC259, groPC756 or seg-2 mutation.
Insights
Bacterial host factors influence single-stranded DNA phage replication. Certain Escherichia coli replication mutants, like dnaM710, restrict phage phiK growth at higher temperatures, impacting viral DNA synthesis.
Area of Science:
- Molecular Biology
- Virology
- Microbiology
Background:
- Single-stranded DNA (ssDNA) phages are vital tools for studying DNA replication mechanisms.
- Bacterial host replication machinery plays a critical role in supporting viral DNA synthesis.
- Understanding host-phage interactions is key to deciphering viral replication strategies.
Purpose of the Study:
- To investigate the role of specific Escherichia coli DNA replication mutants in supporting the growth of ssDNA phages.
- To identify host factors essential for the replication of microvirid phages (e.g., phiK, phiX174, alpha3).
Main Methods:
- Assessing phage phiK multiplication in various E. coli replication mutants (dnaL, dnam, dnaS, dnaZ) at different temperatures.
- Analyzing viral replicative form synthesis and progeny replication in infected dnaZ mutant cells.
- Testing the thermosensitivity of phiX174 and alpha3 phage growth in specific E. coli mutants via transfection.
Main Results:
- Phage phiK grew in dnaL708, dnam709, and dnaS707 mutants without restriction, even at 42°C.
- Growth of phiK was thermosensitive in dnaM710 mutants, showing severe effects at 42°C but not 33°C.
- In dnaZ mutants, parental replicative form of phiK was synthesized, but progeny replication was blocked at restrictive temperatures.
- phiX174 and alpha3 phage growth was thermosensitive in dnaM710 mutants, unlike in dnaL, dnam709, or dnaS707 mutants.
- Microvirid phages could propagate in E. coli cells with groPC or seg-2 mutations, unlike phage lambda.
Conclusions:
- Specific E. coli DNA replication mutants exhibit differential effects on ssDNA phage growth, highlighting distinct host dependencies.
- The dnaM710 gene product is crucial for the replication of certain ssDNA phages at elevated temperatures.
- Host factors encoded by dnaZ and groPC genes are implicated in the replication cycle of microvirid phages.