The product of gene At3g16450.1 from Arabidopsis thaliana is a 32 kDa, 299‐residue protein classified as resembling a myrosinase‐binding protein (MyroBP). MyroBPs are found in plants as part of a complex with the glucosinolate‐degrading enzyme myrosinase, and are suspected to play a role in myrosinase‐dependent defense against pathogens. Many MyroBPs and MyroBP‐related proteins are composed of repeated homologous sequences with unknown structure. We report here the three‐dimensional structure of the At3g16450.1 protein from Arabidopsis, which consists of two tandem repeats. Because the size of the protein is larger than that amenable to high‐throughput analysis by uniform 13C/15N labeling methods, we used stereo‐array isotope labeling (SAIL) technology to prepare an optimally 2H/13C/15N‐labeled sample. NMR data sets collected using the SAIL protein enabled us to assign 1H, 13C and 15N chemical shifts to 95.5% of all atoms, even at a low concentration (0.2 mm) of protein product. We collected additional NOESY data and determined the three‐dimensional structure using the cyana software package. The structure, the first for a MyroBP family member, revealed that the At3g16450.1 protein consists of two independent but similar lectin‐fold domains, each composed of three β‐sheets.

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