Proton NMR studies of .lambda. cro repressor. 2. Sequential resonance assignments of the proton NMR spectrum

Publisher Website
Google Scholar
Abstract
The cro repressor protein from bacteriophage .lambda. has been studied in solution by two-dimensional nuclear magnetic resonance spectroscopy (2D NMR). Following the approach of Wuthrich and co-workers [Wuthrich, K., Wider, G., Wagner, G., and Braun, W. (1982) J. Mol. Biol. 155, 311-319], individual spin systems were identified by J-correlated spectroscopy (COSY) supplemented, where necessary, by relayed coherence transfer spectroscopy (RELAY). Nuclear Overhauser effect spectroscopy (NOESY) was used to obtain sequence-specific assignments. From the two-dimensional spectra, the peptide backbone resonances (NH and C.alpha.H) for 65 of the 66 amino acids were assigned, as well as most of the side chain resonances. The chemical shifts for the assigned protons are reported at 35.degree. C in 10 mM potassium phosphate, pH 6.8, and in 10 mM potassium phosphate, pH, 4.6, 0.2 M KCl, and 0.1 mM EDTA. Small shifts were observed for some resonances upon addition of salt, but no major changes in the spectrum were seen, indicating that no global structural change occurs between these ionic strengths. NOE patterns characteristic of .alpha.-helices, .beta.-strands, ad turns are seen in various regions of the primary sequence. From the location of these regions the secondary structure of cro in solution appears to be virtually identical with the crystal structure [Anderson, W. F., Ohlendorf, D. H., Takeda, Y., and Matthews, B. W. (1981) Nature (London) 209, 754-758]. Missing assignments include the Pro-59 resonances and the peripheral protons of the eight lysine, the three arginine, and three of the five isoleucine residues.
Keywords