Binding of the N-Terminal Domain of the Lactococcal Bacteriophage TP901-1 CI Repressor to Its Target DNA: A Crystallography, Small Angle Scattering, and Nuclear Magnetic Resonance Study. Frandsen, K. H., Rasmussen, K. K., Jensen, M. R., Hammer, K., Pedersen, M., Poulsen, J. N., Arleth, L., & Lo Leggio, L. BIOCHEMISTRY, 52(39):6892-6904, OCT 1, 2013.
doi  abstract   bibtex   
In most temperate bacteriophages, regulation of the choice of lysogenic or lytic life cycle is controlled by a CI repressor protein. Inhibition of transcription is dependent on a helix-turn-helix motif, often located in the N-terminal domain (NTD), which binds to specific DNA sequences (operator sites). Here the crystal structure of the NTD of the CI repressor from phage TP901-1 has been determined at 1.6 angstrom resolution, and at 2.6 angstrom resolution in complex with a 9 bp double-stranded DNA fragment that constitutes a half-site of the O-L operator. This N-terminal construct, comprising residues 2-74 of the CI repressor, is monomeric in solution as shown by nuclear magnetic resonance (NMR), small angle X-ray scattering, and gel filtration and is monomeric in the crystal structures. The binding interface between the NTD and the half-site in the crystal is very similar to the interface that can be mapped by NMR in solution with a full palindromic site. The interactions seen in the complexes (in the crystal and in solution) explain the observed affinity for the O-R site that is lower than that for the O-L site and the specificity for the recognized DNA sequence in comparison to that for other repressors. Compared with many well-studied phage repressor systems, the NTD from TP901-1 CI has a longer extended scaffolding helix that, interestingly, is strongly conserved in putative repressors of Gram-positive pathogens. On the basis of sequence comparisons, we suggest that these bacteria also possess repressor/antirepressor systems similar to that found in phage TP901-1.
@article{ISI:000330099500016,
	Abstract = {{In most temperate bacteriophages, regulation of the choice of lysogenic
   or lytic life cycle is controlled by a CI repressor protein. Inhibition
   of transcription is dependent on a helix-turn-helix motif, often located
   in the N-terminal domain (NTD), which binds to specific DNA sequences
   (operator sites). Here the crystal structure of the NTD of the CI
   repressor from phage TP901-1 has been determined at 1.6 angstrom
   resolution, and at 2.6 angstrom resolution in complex with a 9 bp
   double-stranded DNA fragment that constitutes a half-site of the O-L
   operator. This N-terminal construct, comprising residues 2-74 of the CI
   repressor, is monomeric in solution as shown by nuclear magnetic
   resonance (NMR), small angle X-ray scattering, and gel filtration and is
   monomeric in the crystal structures. The binding interface between the
   NTD and the half-site in the crystal is very similar to the interface
   that can be mapped by NMR in solution with a full palindromic site. The
   interactions seen in the complexes (in the crystal and in solution)
   explain the observed affinity for the O-R site that is lower than that
   for the O-L site and the specificity for the recognized DNA sequence in
   comparison to that for other repressors. Compared with many well-studied
   phage repressor systems, the NTD from TP901-1 CI has a longer extended
   scaffolding helix that, interestingly, is strongly conserved in putative
   repressors of Gram-positive pathogens. On the basis of sequence
   comparisons, we suggest that these bacteria also possess
   repressor/antirepressor systems similar to that found in phage TP901-1.}},
	Author = {Frandsen, Kristian H. and Rasmussen, Kim K. and Jensen, Malene Ringkjobing and Hammer, Karin and Pedersen, Margit and Poulsen, Jens-Christian N. and Arleth, Lise and Lo Leggio, Leila},
	Date-Added = {2017-10-03 14:11:19 +0000},
	Date-Modified = {2017-10-03 14:11:19 +0000},
	Doi = {{10.1021/bi400439y}},
	Issn = {{0006-2960}},
	Journal = {{BIOCHEMISTRY}},
	Month = {{OCT 1}},
	Number = {{39}},
	Orcid-Numbers = {{Arleth, Lise/0000-0002-4694-4299 Lo Leggio, Leila/0000-0002-5135-0882 Frandsen, Kristian E. H./0000-0002-7136-9820}},
	Pages = {{6892-6904}},
	Researcherid-Numbers = {{Arleth, Lise/M-4705-2014 Lo Leggio, Leila/B-4287-2015 }},
	Title = {{Binding of the N-Terminal Domain of the Lactococcal Bacteriophage TP901-1 CI Repressor to Its Target DNA: A Crystallography, Small Angle Scattering, and Nuclear Magnetic Resonance Study}},
	Unique-Id = {{ISI:000330099500016}},
	Volume = {{52}},
	Year = {{2013}},
	Bdsk-Url-1 = {http://dx.doi.org/10.1021/bi400439y%7D}}
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