Three-dimensional structure in solution of barwin, a protein from barley seed

Area of Science:

• Biochemistry and Molecular Biology
• Structural Biology
• Plant Science

Background:

• Barwin is a 125-residue basic protein closely related to domains in plant wound-induced proteins.
• Understanding its structure is crucial for elucidating its function in plant defense mechanisms.

Purpose of the Study:

• To determine the solution structure of barwin using nuclear magnetic resonance (NMR) spectroscopy.
• To investigate the binding site of barwin to N-acetylglucosamine and determine the complex's dissociation constant.

Main Methods:

• 1H nuclear magnetic resonance (NMR) spectroscopy was employed for structural determination.
• Nuclear Overhauser effects (NOEs) were assigned, and distance and torsion angle restraints were used for structure calculation via distance geometry, simulated annealing, and restrained energy minimization.
• One-dimensional 1H NMR spectroscopy was used to determine the dissociation constant of the barwin-N-acetylglucosamine complex.

Main Results:

• A high-resolution solution structure of barwin was obtained, with low violations of distance and torsion angle restraints.
• The structure is characterized by a prominent four-stranded antiparallel beta-sheet, two parallel beta-sheets, and four short alpha-helices.
• The binding site of barwin to tetrameric N-acetylglucosamine was qualitatively mapped, and the dissociation constant was determined.

Conclusions:

• The determined structure provides insights into the molecular architecture of barwin.
• The findings contribute to understanding the function of barwin in plant responses to wounding.
• The characterization of barwin's interaction with N-acetylglucosamine offers a basis for further functional studies.