Interaction between the phage HK022 Nun protein and the nut RNA of phage lambda.
AUTOR(ES)
Chattopadhyay, S
RESUMO
The nun gene product of prophage HK022 excludes phage lambda infection by blocking the expression of genes downstream from the lambda nut sequence. The Nun protein functions both by competing with lambda N transcription-antitermination protein and by actively inducing transcription termination on the lambda chromosome. We demonstrate that Nun binds directly to a stem-loop structure within nut RNA, boxB, which is also the target for the N antiterminator. The two proteins show comparable affinities for boxB and they compete with each other. Their interactions with boxB are similar, as shown by RNase protection experiments, NMR spectroscopy, and analysis of boxB mutants. Each protein binds the 5' strand of the boxB stem and the adjacent loop. The stem does not melt upon the binding of Nun or N, as the 3' strand remains sensitive to a double-strand-specific RNase. The binding of RNA partially protects Nun from proteolysis and changes its NMR spectra. Evidently, although Nun and N bind to the same surface of boxB RNA, their respective complexes interact differently with RNA polymerase, inducing transcription termination or antitermination, respectively.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=40310Documentos Relacionados
- Phage HK022 Nun protein represses translation of phage λ N (transcription termination/translation repression)
- Specificity determinants in the attachment sites of bacteriophages HK022 and lambda.
- Escherichia coli NusA is required for efficient RNA binding by phage HK022 Nun protein
- The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coli RNA polymerase without abolishing its catalytic activities
- The carboxyl terminus of phage HK022 Nun includes a novel zinc-binding motif and a tryptophan required for transcription termination