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1H, 15N and 13C NMR assignments of the 434 repressor fragments 1-63 and 44-63 unfolded in 7 M urea.

Authors
  • Neri, D
  • Wider, G
  • Wüthrich, K
Type
Published Article
Journal
FEBS Letters
Publisher
Wiley (John Wiley & Sons)
Publication Date
Jun 01, 1992
Volume
303
Issue
2-3
Pages
129–135
Identifiers
PMID: 1607010
Source
Medline
License
Unknown

Abstract

An E. coli overexpression system for the N-terminal domain of the 434 repressor with residues 1-63 (434 repressor(1-63)) was constructed and used to produce this polypeptide with uniform 15N-labeling, and with 13C-labeling of the methyl groups of valine and leucine. Using these protein preparations almost complete sequence-specific resonance assignments were obtained for the urea-unfolded form of the 434 repressor(1-63). In addition, the isotope-labeled tryptic peptide, 44-63, was produced by enzymatic cleavage of the recombinant 434 repressor(1-63), and its NMR spectrum was assigned. Corresponding residues in 434 repressor(1-63) and 434 repressor(44-63) in 7 M urea were found to have nearly identical chemical shifts, and in both species similar deviations from 1H random coil shifts were found as previously in 434 repressor(1-69). These indicate the presence of residual non-random structure in the polypeptide segment 50-60. The present NMR assignments, which include stereospecific assignments for the diastereotopic methyl groups of Val and Leu, are the basis for detailed studies of this residual structure in the urea-unfolded form of the 434 repressor.

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