Interaction of the Cro repressor with the lysis/lysogeny switch of the Lactobacillus casei temperate bacteriophage A2

摘要: The transcriptional switch region of Lactobacillus casei temperate bacteriophage A2 contains three similar 20 bp operator subsites, O1 ,O 2 and O3, which are interspersed between the divergent promoters PR PL. Cro protein binds initially to overlaps N35 PL, excluding RNA polymerase (r A -RNAP) from it. This results in switching off cI transcription directs incoming phage into lytic cycle. At higher concentrations, also and/or O2, overlap PR, probably introducing a bend intervening DNA. interaction induces DNA looping, provokes subsequent displacement r -RNAP PR. Consequently, abolishes binding genetic and, presumably, its own synthesis, contributing indirectly entry development late stages.