Premium
Bacteriophage and host mutants causing the rolling‐circle λ DNA replication early after infection
Author(s) -
Konopa Grażyna,
Barańska Sylwia,
Wegrzyn Alicja,
Wegrzyn Grzegorz
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01451-4
Subject(s) - rolling circle replication , dnaa , biology , bacteriophage , dna replication , mutant , lytic cycle , origin of replication , prokaryotic dna replication , myoviridae , phagemid , replicon , replication factor c , concatemer , viral replication , lambda phage , dna , control of chromosome duplication , microbiology and biotechnology , escherichia coli , plasmid , virology , genetics , virus , gene , genome
There are two modes of bacteriophage λ DNA replication during its lytic development in Escherichia coli cells. The circle‐to‐circle (θ) replication predominates at early stages of the phage growth, whereas rolling‐circle (σ) replication occurs late after infection to produce long concatemers that serve as substrates for packaging of λ DNA into phage proheads. The mechanism regulating the switch from θ to σ replication remains unknown. Our previous genetic studies indicated that the bacteriophage λ P ts 1 π A66 mutant cannot replicate at 43°C in the wild‐type E. coli host, but it can replicate in the dnaA46 (ts) mutant. Density shift experiments suggested that the parental DNA molecules of the infecting phage enter σ replication. Here, using electron microscopy, we demonstrate that as soon as 5 min after infection of the dnaA46 (ts) mutant by the λ P ts 1 π A66 phage at 43°C, the σ replication intermediates are highly predominant over θ replication intermediates, contrary to the wild‐type conditions (wild‐type bacteria infected with the λ P + phage). The initiation of replication of the λ P ts 1 π A66 mutant at 43°C was strongly inhibited in the dnaA + host, as demonstrated by electron microscopy and by pulse‐labeling of the phage‐derived plasmid replicon. Implications for the mechanism of the regulation of the switch from θ to σ replication mode are discussed.