PMID:18192369
| Citation |
Kurt, N and Cavagnero, S (2008) Nonnative helical motif in a chaperone-bound protein fragment. Biophys. J. 94:L48-50 |
|---|---|
| Abstract |
The effect of cotranslationally active chaperones on the conformation of incomplete protein chains is poorly understood. The secondary structure of a 77-residue chaperone-bound N-terminal protein fragment corresponding to the first five helices (A-E) of apomyoglobin (apoMb(1-77)) is investigated here at the residue-specific level by multidimensional NMR. The substrate-binding domain of DnaK, DnaK-beta, is employed as a chaperone model. By taking advantage of the improved spectral quality resulting from chaperone deuteration, we find that DnaK-beta-bound apoMb(1-77) displays a region of nonnative helicity at residues away from the main chaperone binding site. The nonnative structural motif comprises portions of the native D and E helices and has similar characteristics to the reported nonnative DE helical region of acid-unfolded full-length apoMb. Upon incorporation of the missing C-terminal amino acids, a structural kink develops between residues 56 and 57, and two separate native D and E helices are generated. This work highlights, for the first time to our knowledge, the presence of a nonnative helical motif in a large chaperone-bound protein fragment under physiologically relevant solution conditions. |
| Links |
PubMed PMC2267123 Online version:10.1529/biophysj.107.127647 |
| Keywords |
Amino Acid Motifs; Apoproteins/chemistry; Apoproteins/ultrastructure; Models, Chemical; Models, Molecular; Myoglobin/chemistry; Myoglobin/ultrastructure; Protein Conformation |
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