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标题：Establishment and Maintenance of Repression by Bacteriophage Lambda: The Role of the cI, cII, and cIII Proteins
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作者：Harrison Echols ; Linda Green
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1971
卷号：68
期号：9
页码：2190-2194
DOI：10.1073/pnas.68.9.2190
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：To define the events necessary for the establishment and maintenance of repression in a {lambda}-infected cell, we have studied the requirements for efficient synthesis of the cI protein ("{lambda}-repressor"). Three classes of {lambda} mutants defective in the establishment of repression are also defective in the appearance of cI protein activity at the normal time. Two of these mutational classes (cII- and cIII-) probably result from inactivation of {lambda}-specified proteins, but the third class (cy-) may involve a structural defect. We conclude that at least three regulatory elements are likely to be required for the normal turn-on of cI protein synthesis in an infected nonlysogenic cell: cII and cIII proteins and an "active" y-region of {lambda} DNA. From these and other results, the complete role of cII and cIII proteins in the establishment of repression may involve a bifunctional regulatory activity: positive regulation of the cI gene and negative regulation of late genes. A possible molecular model for cII and cIII action is discussed. Since the cII and cIII genes are repressed by the cI protein under conditions of stable lysogeny, a separate mechanism is required for the maintenance of cI protein synthesis. After infection of a lysogen by cII- phage, the rate of increase of cI protein activity is substantially greater than after infection of a nonlysogen. From these and other results, the cI protein may also have a bifunctional regulatory activity: positive regulation of the cI gene and negative regulation of early lytic genes.
关键词：E. coli ; lysogeny versus lysis ; cy ^- mutants ; DNA binding