Superinfection immunity and prophage repression in phage P1 IV. The c1 repressor bypass function and the role of c4 repressor in immunity
1978; Elsevier BV; Volume: 85; Issue: 2 Linguagem: Inglês
10.1016/0042-6822(78)90463-4
ISSN1096-0341
AutoresJune R. Scott, Brenda W. West, Jane L. Laping,
Tópico(s)Hepatitis B Virus Studies
ResumoPrevious work indicated that both genes c1 and c4 of phage P1 and P1 are necessary for maintenance of lysogeny and suggested the c4 but not c1 is required for the specificity of superinfection immunity. We now show that c4− P1 lysogens do not express superinfection immunity. In addition, we have isolated mutants in a c1 repressor bypass function (Reb) which permits P1 to grow in the presence of c1+ product. Reb mutants were isolated by selecting for suppression of the virB or c4 phenotype, so synthesis of reb product is negatively controlled by both c4 repressor and by the site at which virB mutants occur. Because some P1reb mutants are suppressed by nonsense suppressors, reb must code for a protein. However, P1reb mutants cannot be complemented by P1reb+ phage in the same cell, which indicates that the reb protein acts predominantly in “cis”. The reb+ product is not needed for prophage replication but is necessary for normal vegetative phage growth by c1+ phage. Possible modes of action of reb are discussed.
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