Host responses influence on the induction of lambda prophage.
Inactivation of bacteriophage lambda CI repressor leads almost exclusively to lytic development. Prophage induction can be initiated either by DNA damage or by heat treatment of a temperature-sensitive repressor. These two treatments also cause a concurrent activation of either the host SOS or heat-shock stress responses respectively. We studied the effects of these two methods of induction on the lytic pathway by monitoring the activation of different lambda promoters, and found that the lambda genetic network co-ordinates information from the host stress response networks. Our results show that the function of the CII transcriptional activator, which facilitates the lysogenic developmental pathway, is not observed following either method of induction. Mutations in the cro gene restore the CII function irrespective of the induction method. Deletion of the heat-shock protease gene ftsH can also restore CII function following heat induction but not following SOS induction. Our findings highlight the importance of the elimination of CII function during induction as a way to ensure an efficient lytic outcome. We also show that, despite the common inhibitory effect on CII function, there are significant differences in the heat- and SOS-induced pathways leading to the lytic cascade.
Rokney
Assaf
A
Department of Molecular Genetics and Biotechnology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel. assafr@ekmd.huji.ac.il
Kobiler
Oren
O
Amir
Amnon
A
Court
Donald L
DL
Stavans
Joel
J
Adhya
Sankar
S
Oppenheim
Amos B
AB
D010582:Bacteriophage lambda / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D008242:Lysogeny / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D016685:Mitomycin / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D013014:SOS Response, Genetics / Q000235:genetics; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D014466:Ultraviolet Rays; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics / Q000502:physiology; D014775:Virus Activation / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects
D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C039000:cII protein, bacteriophage lambda; C016649:phage repressor proteins; D016685:Mitomycin