The K-segment of maize DHN1 mediates binding to anionic phospholipid vesicles and concomitant structural changes

Area of Science:

• Plant molecular biology
• Biochemistry
• Proteomics

Background:

• Dehydrins (DHNs) are intrinsically unstructured plant proteins accumulating during seed development and under abiotic stress.
• Maize DHNs bind to anionic phospholipid vesicles, increasing their alpha-helicity, a process mimicked by sodium dodecyl sulfate.
• DHNs possess a conserved K-segment, a lysine-rich sequence predicted to form an amphipathic alpha-helix involved in molecular interactions.

Purpose of the Study:

• To investigate the role of the K-segment in maize DHN1's interaction with anionic phospholipid vesicles.
• To determine the contribution of the K-segment to the conformational changes observed in DHNs upon binding.

Main Methods:

• Production of three K-segment deletion variants of maize DHN1.
• Lipid vesicle-binding assays to assess protein-lipid interactions.
• Analysis of protein conformational changes, specifically alpha-helicity.

Main Results:

• The K-segment of maize DHN1 is essential for its binding to anionic phospholipid vesicles.
• Deletion of the K-segment significantly reduces or abolishes binding affinity.
• The K-segment's adoption of alpha-helicity accounts for the majority of the conformational change observed in DHNs during membrane interaction.

Conclusions:

• The K-segment is a critical functional domain for DHN-membrane interactions.
• The structural transition of the K-segment to an alpha-helix upon binding is key to DHN function.
• This structural adaptation likely contributes to the stabilization of cellular components, such as membranes, under various stress conditions.