BIPARTITE FUNCTION OF A SMALL RNA HAIRPIN IN TRANSCRIPTION ANTITERMINATION IN BACTERIOPHAGE-LAMBDA
BIPARTITE FUNCTION OF A SMALL RNA HAIRPIN IN TRANSCRIPTION ANTITERMINATION IN BACTERIOPHAGE-LAMBDA
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DOI：
10.1073/pnas.92.9.4061
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发表时间：
1995-04-25
影响因子：
11.1
通讯作者：
DAS, A
中科院分区：
文献类型：
--
作者：
CHATTOPADHYAY, S;GARCIAMENA, J;DAS, A
Transcription of downstream genes in the early operons of phage lambda requires a promoter-proximal element known as nut, This site acts in cis in the form of RNA to assemble a transcription antitermination complex which is composed of lambda N protein and at least four host factors, The nut-site RNA contains a small stem-loop structure called boxB. Here, we show that boxB RNA binds to N protein with high affinity and specificity, White N binding is confined to the 5' subdomain of the stem-loop, specific N recognition relies on both an intact stem-loop structure and two critical nucleotides in the pentamer loop, Substitutions of these nucleotides affect both N binding and antitermination, Remarkably, substitutions of other loop nucleotides also diminish antitermination in vivo, yet they have no detectable effect on N binding in vitro, These 3' loop mutants fail to support antitermination in a minimal system with RNA polymerase (RNAP), N, and the host factor NusA, Furthermore, the ability of NusA to stimulate the formation of the RNAP-boxB-N complex is diminished with these mutants, Hence, we suggest that boxB RNA performs two critical functions in antitermination, First, boxB binds to N and secures it near RNAP to enhance their interaction, presumably by increasing the local concentration of N, Second, boxB cooperates with NusA, most likely to bring N and RNAP in close contact and transform RNAP to the termination-resistant state.
