Interaction between Basic 7S Globulin and Leginsulin in Soybean [Glycine max]: A Structural Insight

In soybean, a small hormone like peptide, leginsulin was found to bind Basic 7S Globulin (Bg7S) and stimulate its tyrosine kinase activity. The NMR-structure of leginsulin, along with crystal structure of Bg7S, was used to create a rigid docking model, followed by flexible refinement of the interaction complex. This study provides structural insights into the binding of leginsulin to Bg7S. The complex is stabilized predominantly by hydrophobic forces and hydrogen bonds. The cleft is lined to a large extent by the cysteine rich region of the α-subunit of chain D as well as the carboxylterminal region of α-subunit of chain A. The model is in agreement with the available experimental evidence for the hotspot regions of Bg7S and leginsulin. We also observed another similar site on the surface of Bg7S by virtue of its pseudo- 222 symmetry. We have further hypothesized that two leginsulin molecules may bind to Bg7S in its crystal structure or tetrameric form.