MBIO 4600 Lecture Notes - Lecture 22: Lysogenic Cycle, Ciii-Dt, Fried Egg
25 Dec 2015
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Ci, cii, and ciii genes (mutants will form clear plaques) Decision between lytic and lysogeny depends on outcome of the competition of cii gene product and replication gene products, and cro gene product. Decision between lytic and lysogeny depends on the presence of cii and the physiological state of the host cell (lytic cycle most of the time) Low vs. high multiplicity of infection (moi) Attp (attachment phage) and attb (attachment bacteria) site with. Int promotes integration common core sequence o : gcttt(tttatac)tta. Note prophage map different from head map (a/r vs. int/j) due to site-specific integration. Ci binds operator sites in pr and pl repressing transcription. In prophage state: ci transcribed from prm (located immediate upstream of ci, ci repressor synthesis tightly regulated. Ci dimer binds first to or1 site repressing transcription from pr. Ci dimer then binds to or2 forming tetramer with dimer at or1 site. Likewise for ci dimers to ol1 and ol2.
