Foldon, the natural trimerization domain of T4 fibritin, dissociates into a monomeric A-state form containing a stable beta-hairpin: Atomic details of trimer dissociation and local beta-hairpin stability from residual dipolar couplings

Sebastian Meier, S. Guthe, T. Kiefhaber, S. Grzesiek

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The C-terminal domain of T4 fibritin (foldon) is obligatory for the formation of the fibritin trimer structure and can be used as an artificial trimerization domain. Its native structure consists of a trimeric-hairpin propeller. At low pH, the foldon trimer disintegrates into a monomeric (A-state) form that has similar properties as that of an early intermediate of the trimer folding pathway. The formation of this A-state monomer from the trimer, its structure, thermodynamic stability equilibrium association and folding dynamics have been characterized to atomic detail by modern high-resolution NMR techniques. The foldon A-state monomer forms a beta-hairpin with intact and stable H-bonds that is similar to the monomer in the foldon trimer, but lacks a defined structure in its N and C-terminal parts. Its thermodynamic stability in pure water is comparable to designed hairpins stabilized in alcohol/ water mixtures. Details of the thermal unfolding of the foldon A-state have been characterized by chemical shifts and residual dipolar couplings (RDCs) detected in inert, mechanically stretched polyacrylamide gels. At the onset of the thermat transition, uniform relative changes in RDC values indicate a uniform decrease of local N-H-N and C-alpha-H-alpha order parameters for the hairpin strand residues. In contrast, near-turn residues show particular thermal stability in RDC values and hence in local order parameters. This coincides with increased transition temperatures of the beta-turn residues observed by chemical shifts. At high temperatures, the RDCs converge to non-zero average values consistent with predictions from random chain polymer models. Residue-specific deviations above the unfolding transition reveal the persistence of residual order around proline residues, large hydrophobic residues and at the beta-turn. (C) 2004 Elsevier Ltd. All rights reserved.
Original languageEnglish
JournalJournal of Molecular Biology
Issue number4
Pages (from-to)1051-1069
Number of pages19
Publication statusPublished - 2004
Externally publishedYes


  • Hydrogen Bonding
  • Models, Molecular
  • Protein Denaturation
  • Protein Folding
  • Protein Structure, Quaternary
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins
  • Thermodynamics
  • Viral Proteins
  • fibritin protein, Enterobacteria phage T4
  • alcohol
  • amino acid derivative
  • foldon
  • monomer
  • protein derivative
  • unclassified drug
  • water
  • amino terminal sequence
  • article
  • carboxy terminal sequence
  • controlled study
  • dissociation
  • high temperature
  • nonhuman
  • nuclear magnetic resonance
  • pH
  • priority journal
  • protein analysis
  • protein domain
  • structure analysis
  • thermostability
  • NMR spectroscopy
  • order parameter
  • protein folding
  • structure
  • thermodynamics
  • RDC - residual dipolar coupling
  • RMSD - root-mean-square deviation
  • NOE - nuclear Overhauser enhancement
  • folding
  • dsDNA Viruses Viruses Microorganisms (Double-Stranded DNA Viruses, Microorganisms, Viruses) - Myoviridae [03101] T4 bacteriophage common Enterobacteria phage T4 species
  • Facultatively Anaerobic Gram-Negative Rods Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Enterobacteriaceae [06702] Escherichia coli species expression system strain-BL21(DE3)
  • beta-hairpin
  • fibritin
  • T4 fibritin foldon
  • 02502, Cytology - General
  • 10060, Biochemistry studies - General
  • 10064, Biochemistry studies - Proteins, peptides and amino acids
  • 30500, Morphology and cytology of bacteria
  • 31000, Physiology and biochemistry of bacteria
  • 33502, Virology - General and methods
  • chemical shift imaging imaging and microscopy techniques, laboratory techniques
  • high-resolution NMR laboratory techniques, spectrum analysis techniques
  • polyacrylamide gel electrophoresis electrophoretic techniques, laboratory techniques
  • 1U0P Protein Data Bank amino acid sequence
  • Biochemistry and Molecular Biophysics
  • Cell Biology

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