1U0P

Stable A-state hairpin of T4 fibritin foldon

Summary for 1U0P

• Entry DOI: 10.2210/pdb1u0p/pdb
• Related: 1rfo
• Descriptor: fibritin (1 entity in total)
• Functional Keywords: beta-hairpin, hairpin, folding nucleus, structural protein
• Biological source: Enterobacteria phage Ox2
• Total number of polymer chains: 1
• Total formula weight: 3084.46

Authors

Meier, S.,Guthe, S.,Kiefhaber, T.,Grzesiek, S. (deposition date: 2004-07-14, release date: 2005-02-22, Last modification date: 2024-05-22)

Primary citation

Meier, S.,Guthe, S.,Kiefhaber, T.,Grzesiek, S.
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
J.Mol.Biol., 344:1051-1069, 2004

PubMed Abstract: 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 beta-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 thermal transition, uniform relative changes in RDC values indicate a uniform decrease of local N-HN and Calpha-Halpha 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.

PubMed: 15544812
DOI: 10.1016/j.jmb.2004.09.079

Experimental method

SOLUTION NMR