New Insights into the Phage Genetic Switch: Effects of Bacteriophage Lambda Operator Mutations on DNA Looping and Regulation of PR, PL, and PRM.
New Insights into the Phage Genetic Switch: Effects of Bacteriophage Lambda Operator Mutations on DNA Looping and Regulation of PR, PL, and PRM.
复制标题
对噬菌体遗传开关的新见解：噬菌体 Lambda 算子突变对 DNA 循环以及 PR、PL 和 PRM 调节的影响。
DOI：
10.1016/j.jmb.2016.08.027
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发表时间：
2016
影响因子：
5.6
通讯作者：
Adhya,Sankar
中科院分区：
文献类型：
--
作者：
Lewis,DaleEA;Gussin,GaryN;Adhya,Sankar
One of the best understood systems in genetic regulatory biology is the so-called “genetic switch” that determines the choice the phage-encoded CI repressor binds cooperatively to tripartite operators,OLandOR, in a defined pattern, thus blocking the transcription at two lytic promoters,PLandPR, and auto-regulating the promoter,PRM, which directs CI synthesis by the prophage. Fine-tuning of the maintenance of lysogeny is facilitated by interactions between CI dimers bound toORandOLthrough the formation of a loop by the intervening DNA segment. By using a purifiedin vitrotranscription system, we have genetically dissected the roles of individual operator sites in the formation of the DNA loop and thus have gained several new and unexpected insights into the system. First, although bothORandOLare tripartite, the presence of only a single active CI binding site in one of the two operators is sufficient for DNA loop formation. Second, inPL, unlike inPR, the promoter distal operator site,OL3, is sufficient to directly repressPL. Third, DNA looping mediated by the formation of CI octamers arising through the interaction of pairs of dimers bound to adjacent operator sites inORandOLdoes not requireORandOLto be aligned “in register”, that is, CI bound to “out-of-register” sub-operators, for example,OL1 ~Ol2 andOR2 ~OR3, can also mediate loop formation. Finally, based on an examination of the mechanism of activation ofPRMwhen onlyOR1 orOR2 are wild type, we hypothesize that RNA polymerase bound atPRinterferes with DNA loop formation. Thus, the formation of DNA loops involves potential interactions between proteins bound at numerouscis-acting sites, which therefore very subtly contribute to the regulation of the “switch”.
