title: Large palindromes in the lambda phage genome are preserved in a rec+ host by inhibiting lambda DNA replication.
abstract: A large palindrome carried by phage lambda has been shown to prevent growth of the phage on a rec+ strain of Escherichia coli. The phage do form plaques on recBC sbcB strains, but the palindrome is not stable--deletions that either destroy the palindrome or diminish its size overgrow the original engineered palindrome-containing phage. We have prepared stocks of lambda carrying a palindrome that is 2 X 4200 base pairs long. These phage stocks are produced by induction of a lysogen in which the two halves of the palindrome are stored at opposite ends of the prophage and are of sufficient titer (10(9) phage per ml) to enable one-step growth experiments with replication-blocked phage. We find that the large palindrome as well as a lesser palindrome of 2 X 265 base pairs are recovered intact among particles carrying unreplicated chromosomes following such an infection of a rec+ host. We propose that DNA replication drives the extrusion of palindromic sequences in vivo, forming secondary structures that are substrates for the recBC and sbcB gene products.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D004261:DNA Replication; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000235:genetics*; D005814:Genes, Viral; D009690:Nucleic Acid Conformation; D014779:Virus Replication
chemical_list: D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli