Very fast folding and association of a trimerization domain from bacteriophage T4 fibritin

S. Guthe, L. Kapinos, A. Moglich, Sebastian Meier, S. Grzesiek, T. Kiefhaber

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The foldon domain constitutes the C-terminal 30 amino acid residues of the trimeric protein fibritin from bacteriophage T4. Its function is to promote folding and trimerization of fibritin. We investigated structure, stability and folding mechanism of the isolated foldon domain. The domain folds into the same trimeric beta-propeller structure as in fibritin and undergoes a two-state unfolding transition from folded trimer to unfolded monomers. The folding kinetics involve several consecutive reactions. Structure formation in the region of the single beta-hairpin of each monomer occurs on the submillisecond timescale. This reaction is followed by two consecutive association steps with rate constants of 1.9(+/-0.5) x 10(6) M-1 s(-1) and 5.4(+/-0.3) x 10(6) M-1 s(-1) at 0.58 M GdmCl, respectively. This is similar to the fastest reported bimolecular association reactions for folding of dimeric proteins. At low concentrations of protein, folding shows apparent third-order kinetics. At high concentrations of protein, the reaction becomes almost independent of protein concentrations with a half-time of about 3 ms, indicating that a first-order folding step from a partially folded trimer to the native protein (k = 210(+/-20) s(-1)) becomes rate-limiting. Our results suggest that all steps on the folding/ trimerization pathway of the foldon domain are evolutionarily optimized for rapid and specific initiation of trimer formation during fibritin assembly. The results further show that beta-hairpins allow efficient and rapid protein-protein interactions during folding. (C) 2004 Elsevier Ltd. All rights reserved.
Original languageEnglish
JournalJournal of Molecular Biology
Issue number4
Pages (from-to)905-915
Publication statusPublished - 2004
Externally publishedYes


  • PROTEIN folding
  • Bacteriophage T4
  • Cyclophilins
  • Kinetics
  • Protein Folding
  • Protein Structure, Tertiary
  • Time Factors
  • Viral Proteins
  • fibritin protein, Enterobacteria phage T4
  • EC 5.2.1.- Cyclophilins
  • article
  • bacteriophage T4
  • carboxy terminal sequence
  • concentration response
  • controlled study
  • kinetics
  • molecular evolution
  • nonhuman
  • priority journal
  • protein domain
  • protein folding
  • protein structure
  • F-moc, N-(9-fluorenyl)methoxycarbonyl
  • Fast folding
  • GdmCl, guanidinium chloride
  • Prolyl isomerization
  • Protein association
  • Protein folding
  • RDC, residual dipolar coupling
  • Trimeric proteins
  • NMR
  • protein association
  • trimeric proteins
  • prolyl isomerization
  • fast folding
  • beta-hairpin
  • foldon domain folding kinetics, folding mechanism, single beta-hairpin, stability, structure, trimeric beta-propeller structure
  • protein-protein interactions folding
  • dsDNA Viruses Viruses Microorganisms (Double-Stranded DNA Viruses, Microorganisms, Viruses) - Myoviridae [03101] Bacteriophage T4 common
  • amino acid
  • dimeric proteins folding, speed
  • fibritin folding, foldon domain, illustration, speed, trimeric protein, trimerization
  • protein concentration, kinetics
  • 10060, Biochemistry studies - General
  • 10064, Biochemistry studies - Proteins, peptides and amino acids
  • 33502, Virology - General and methods
  • Biochemistry and Molecular Biophysics

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