Context and conformation dictate function of a transcription antitermination switch
Abstract
In bacteriophage λ, transcription elongation is regulated by the N protein, which binds a nascent mRNA hairpin (termed boxB) and enables RNA polymerase to read through distal terminators. We have examined the structure, energetics and in vivo function of a number of N−boxB complexes derived from in vitro protein selection. Trp18 fully stacks on the RNA loop in the wild-type structure, and can become partially or completely unstacked when the sequence context is changed three or four residues away, resulting in a recognition interface in which the best binding residues depend on the sequence context. Notably, in vivo antitermination activity correlates with the presence of a stacked aromatic residue at position 18, but not with N−boxB binding affinity. Our work demonstrates that RNA polymerase responds to subtle conformational changes in cis-acting regulatory complexes and that approximation of components is not sufficient to generate a fully functional transcription switch.
Additional Information
© 2003 Nature Publishing Group. Received 28 March 2003; Accepted 23 July 2003; Published online: 21 September 2003. We thank N. Franklin for the gifts of the two-plasmid N expressor−β-galactosidase reporter constructs, plasmid pMS7 and N−tester strain, P. von Hippel for the gift of pET-N1 plasmid and N protein, P. Legault for sharing the coordinates of the λ phage N peptide−boxB RNA complex and J.H. Richards, C.S. Parker and members of the Roberts laboratory for helpful comments on the manuscript. This work was supported by grants from US National Science Foundation (NSF) and National Institutes of Health (NIH) to R.W.R. R.W.R. is an Alfred P. Sloan research fellow, A.F. is an ACS postdoctoral fellow and T.T.T. was supported by an NIH training grant.Attached Files
Supplemental Material - nsb983-S1.pdf
Supplemental Material - nsb983-S2.pdf
Supplemental Material - nsb983-S3.pdf
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Additional details
- Eprint ID
- 56430
- DOI
- 10.1038/nsb983
- Resolver ID
- CaltechAUTHORS:20150407-130603552
- NSF
- NIH
- Alfred P. Sloan Foundation
- American Chemical Society (ACS)
- Created
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2015-04-07Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field