<sup>17</sup>O NMR Studies of Yeast Ubiquitin in Aqueous Solution and in the Solid State
Binyang Lin, Ivan Hung, Zhehong Gan, Po‐Hsiu Chien, Holly L. Spencer, Steven P. Smith, Gang Wu
Abstract
Abstract We report a general method for amino acid‐type specific 17 O‐labeling of recombinant proteins in Escherichia coli . In particular, we have prepared several [1‐ 13 C, 17 O]‐labeled yeast ubiquitin (Ub) samples including Ub‐[1‐ 13 C, 17 O]Gly, Ub‐[1‐ 13 C, 17 O]Tyr, and Ub‐[1‐ 13 C, 17 O]Phe using the auxotrophic E. coli strain DL39 GlyA λDE3 ( asp C − tyr B − ilv E − gly A − λDE3). We have also produced Ub‐[η‐ 17 O]Tyr, in which the phenolic group of Tyr59 is 17 O‐labeled. We show for the first time that 17 O NMR signals from protein terminal residues and side chains can be readily detected in aqueous solution. We also reported solid‐state 17 O NMR spectra for Ub‐[1‐ 13 C, 17 O]Tyr and Ub‐[1‐ 13 C, 17 O]Phe obtained at an ultrahigh magnetic field, 35.2 T (1.5 GHz for 1 H). This work represents a significant advance in the field of 17 O NMR studies of proteins.