Structural characterizations and bioactivity of PYL9-(+)-ABA.

<p>(<b>A</b>) Two protomers of PYL9-(+)-ABA in each asymmetric unit. 2<i>F_o</i>−<i>F_c</i> electron density map of (+)-ABA at 1.0σ. (<b>B</b>) One protomer of PYL9-(+)-ABA with five cysteine residues (green) and a disulphide formed between C34 and C159. (<b>C</b>) The monomeric state of PYL9 in solution was confirmed by the sedimentation velocity. The sample purity for sedimentation velocity experiments was detected by SDS-PAGE and then Coomassie Brilliant Blue staining in the subplot. (<b>D</b>) The C159 was the key residue in disulphide bond, while the C29 competed with the C34 to form the disulphide bond. PYL9 and its mutants were under different oxidation-reduction conditions for SDS-PAGE. 1% βme or 1% βme +100 mM DTT was used as reducing agents to disrupt the disulphide bond. Only C159S mutant was not affected by the reducing agents (black arrow).