A Gibberellin Mimetic Peptide Recognized by an Anti-gibberellin Monoclonal Antibody

摘要

Gibberellins (GAs) are a class of plant hormones and play important roles in various plant growth phenomena, including seed germination, stem elongation, and flower development. However, a receptor for GAs still remains unidentified. If a peptidyl mimotope of GA is available, it will provide useful probes for the study of GA receptor, because of easy modification such as biotinylation, photoaffinity labeling and radio isotope labeling. Two kind of homologous peptides, ACLPWSDGPC (SD) and ACLPWGTGPC (GT), were recently screened as peptidyl mimotopes of GA_4 against monoclonal antibody (mAb) 4-B8(8)/E9 by phage display method . Both peptides were cyclized by a disulfide cross-link between Cys~2 and Cys~(10) . Unfortunately, synthetic peptides SD and GT showed neither promotive nor inhibitory effects on GA action in alpha-amylase induction in barley aleurone tissue or shoot elongation of dwarf rice seedlings. In order to investigate the interaction between the GA mimetic peptide and the antibody, we first determined the solution structure of the peptide SD by two-dimensional (2D) NMR spectroscopy. The epitopes of the peptide to the antibody were assessed by saturation transfer difference (STD)-NMR experiments. Further, the computational docking simulation between the peptide and the antibody was performed to investigate the interaction between the peptide and the mAb.