2JOF

The Trp-cage: Optimizing the Stability of a Globular Miniprotein

Summary for 2JOF

• Entry DOI: 10.2210/pdb2jof/pdb
• Related: 1jrj 1l2y
• NMR Information: BMRB: 15169
• Descriptor: TRP-CAGE (1 entity in total)
• Functional Keywords: de novo protein, miniprotein, two-state folding, trp-cage
• Biological source: synthetic construct
• Total number of polymer chains: 1
• Total formula weight: 2088.24

Authors

Barua, B.,Andersen, N.H. (deposition date: 2007-03-09, release date: 2008-03-04, Last modification date: 2024-05-08)

Primary citation

Barua, B.,Lin, J.C.,Williams, V.D.,Kummler, P.,Neidigh, J.W.,Andersen, N.H.
The Trp-cage: optimizing the stability of a globular miniprotein
Protein Eng.Des.Sel., 21:171-185, 2008

PubMed Abstract: The Trp-cage, as the smallest miniprotein, remains the subject of numerous computational and experimental studies of protein folding dynamics and pathways. The original Trp-cage (NLYIQWLKDGGPSSGRPPPS, Tm = 42 degrees C) can be significantly stabilized by mutations; melting points as high as 64 degrees C are reported. In helical portions of the structure, each allowed replacement of Leu, Ile, Lys or Ser residues by Ala results in a 1.5 (+/-0.35) kJ/mol fold stabilization. No changes in structure or fluxionality of the core results upon stabilization. Contrary to the initial hypothesis, specific Pro/Trp interactions are not essential for core formation. The entropic advantage of Pro versus Ala (DeltaDeltaS(U) = 11 +/- 2 J/mol K) was measured at the solvent-exposed P17 site. Pro-Ala mutations at two of the three prolines (P12 and P18) that encage the indole ring result in less fold destabilization (2.3-3.4 kJ/mol). However, a P19A mutation reduces fold stability by 16 kJ/mol reflecting a favorable Y3/P19 interaction as well as Trp burial. The Y3/P19 hydrophobic staple interaction defines the folding motif as an 18-residue unit. Other stabilizing features that have been identified include a solvent-exposed Arg/Asp salt bridge (3.4-6 kJ/mol) and a buried H-bonded Ser side chain ( approximately 10 kJ/mol).

PubMed: 18203802
DOI: 10.1093/protein/gzm082

Experimental method

SOLUTION NMR