2kbl

From Proteopedia

NMR Structure of a Monomeric Folding Intermediate Reveals the Structural Basis for Rapid Assembly of an Evolutionary Optimized Trimerization Module

Structural highlights

2kbl is a 1 chain structure with sequence from Escherichia virus T4. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Solution NMR
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

WAC_BPT4 Chaperone responsible for attachment of long tail fibers to virus particle. Forms the fibrous structure on the neck of the virion called whiskers. During phage assembly, 6 fibritin molecules attach to each virion neck through their N-terminal domains, to form a collar with six fibers ('whiskers').

Publication Abstract from PubMed

Efficient formation of specific intermolecular interactions is essential for self-assembly of biological structures. The foldon domain is an evolutionarily optimized trimerization module required for assembly of the large, trimeric structural protein fibritin from phage T4. Monomers consisting of the 27 amino acids comprising a single foldon domain subunit spontaneously form a natively folded trimer. During assembly of the foldon domain, a monomeric intermediate is formed on the submillisecond time scale, which provides the basis for two consecutive very fast association reactions. Mutation of an intermolecular salt bridge leads to a monomeric protein that resembles the kinetic intermediate in its spectroscopic properties. NMR spectroscopy revealed essentially native topology of the monomeric intermediate with defined hydrogen bonds and side-chain interactions but largely reduced stability compared to the native trimer. This structural preorganization leads to an asymmetric charge distribution on the surface that can direct rapid subunit recognition. The low stability of the intermediate allows a large free-energy gain upon trimerization, which serves as driving force for rapid assembly. These results indicate different free-energy landscapes for folding of small oligomeric proteins compared to monomeric proteins, which typically avoid the transient population of intermediates.

NMR structure of a monomeric intermediate on the evolutionarily optimized assembly pathway of a small trimerization domain.,Habazettl J, Reiner A, Kiefhaber T J Mol Biol. 2009 May 29;389(1):103-14. Epub 2009 Apr 8. PMID:19361528^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Habazettl J, Reiner A, Kiefhaber T. NMR structure of a monomeric intermediate on the evolutionarily optimized assembly pathway of a small trimerization domain. J Mol Biol. 2009 May 29;389(1):103-14. Epub 2009 Apr 8. PMID:19361528 doi:10.1016/j.jmb.2009.03.073