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：1973
卷号：70
期号：4
页码：1078-1082
DOI：10.1073/pnas.70.4.1078
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The N protein of bacteriophage lambda is a positive regulator of early {lambda} gene expression. In a {lambda}trp transducing phage, {lambda}trp46Nam, the synthesis of trp enzymes in vivo is also dependent on the presence of active N protein. The DNA of this phage has been used in a protein-synthesizing system in vitro to develop a biochemical assay for the activity of the N protein. From the following observations it appears that it is the N protein itself that stimulates trp enzyme synthesis in vitro. An activity that stimulates trp enzyme synthesis can be made in vitro by {lambda}N+ DNA but not by {lambda}Nam DNA. This activity can also be detected in extracts of induced {lambda}N+ lysogens but not of {lambda}Nam lysogens. Furthermore, the activity is temperature sensitive in similar extracts of {lambda}Nts lysogens. No such activity is detectable in extracts of induced lysogens of {lambda}imm21. This phage makes all {lambda}-coded gene products outside the immunity region, but lacks an N protein activity able to substitute for N{lambda} protein in vivo. Our experiments also show that the action of N protein is inhibited by the cI repressor protein in vivo as it is in vivo.
关键词：N protein assay ; temperature-sensitive N mutant protein ; N λ and N 21 specificity ; λ repressor
