Structure and dynamics of the tetrameric mnt repressor and a model for its DNA complex

I M Nooren, G E Folkers, R Kaptein, R T Sauer, R Boelens

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Abstract The tetrameric Mnt repressor of bacteriophage P22 consists of two dimeric DNA-binding domains and a tetramerization domain. The NOE and chemical shift data demonstrate that the structures of the domains in the wild-type repressor protein are similar to those of the separate domains, the three-dimensional structures of which have been determined previously. (15)N relaxation measurements show that the linker that connects the anti-parallel four-helix bundle with the two β-sheet DNA-binding dimers is highly flexible. No evidence was found for interactions between the distinct modules. The (15)N relaxation properties of the two domains differ substantially, confirming their structural independence. A model in which one two-stranded coiled coil of the four-helix bundle is attached to one N-terminal dimer is most consistent with the biochemical data and (15)N relaxation data. For the Mnt-DNA complex this geometry fits with a model in which the two β-sheet DNA-binding domains are bound at two successive major grooves of the Mnt operator and the tetramerization domain is packed between these two DNA-bound dimers. In such a model the two-fold symmetry axis of the four-helix bundle coincides with that of the operator sequence and the two bound dimers. Bending of the Mnt operator of approximately 30° upon binding of the tetramer, as measured by gel-shift assays, is in agreement with this model of the Mnt-DNA complex.

Original languageEnglish
Pages (from-to)113-22
Number of pages10
JournalJournal of Biomolecular Structure and Dynamics
Volume17 Suppl 1
DOIs
Publication statusPublished - 2000

Keywords

  • Amino Acid Sequence
  • DNA
  • Models, Molecular
  • Molecular Sequence Data
  • Repressor Proteins
  • Viral Proteins
  • Viral Regulatory and Accessory Proteins

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