Plant cell-wall cross-links by REDOR NMR spectroscopy.
We present a new method that integrates selective biosynthetic labeling and solid-state NMR detection to identify in situ important protein cross-links in plant cell walls. We have labeled soybean cells by growth in media containing l-[ring-d(4)]tyrosine and l-[ring-4-(13)C]tyrosine, compared whole-cell and cell-wall (13)C CPMAS spectra, and examined intact cell walls using (13)C{(2)H} rotational echo double-resonance (REDOR) solid-state NMR. The proximity of (13)C and (2)H labels shows that 25% of the tyrosines in soybean cell walls are part of isodityrosine cross-links between protein chains. We also used (15)N{(13)C} REDOR of intact cell walls labeled by l-[ε-(15)N,6-(13)C]lysine and depleted in natural-abundance (15)N to establish that the side chains of lysine are not significantly involved in covalent cross-links to proteins or sugars.
Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States. cegelski@stanford.edu
Lynette
L
Cegelski
Robert D
RD
O'Connor
Dirk
D
Stueber
Manmilan
M
Singh
Barbara
B
Poliks
Jacob
J
Schaefer
D002473:Cell Wall / Q000737:chemistry*; D002478:Cells, Cultured; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010940:Plant Proteins / Q000032:analysis*; D013025:Glycine max / Q000737:chemistry / Q000166:cytology; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis
D010940:Plant Proteins; D014443:Tyrosine; C035129:isodityrosine