Submitted to: Plant Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2003
Publication Date: 3/20/2002
Citation: SOULAGES, J.L., KIM, K., WALTERS, C.T., CUSHMAN, J.C. 2002 TEMPERATURE-INDUCED HELIX/RANDOM COIL TRANSITIONS IN A GROUP 1 LATE EMBRYOGENESIS ABUNDANT PROTEIN FROM SOYBEAN. PLANT PHYSIOLOGY. 128: 1-11. Interpretive Summary: The ubiquitous expression of late-embryogenic-abundant proteins in plants in response to water or temperature stress has lead to the widespread belief that these proteins protect cells from damage during stress. The proteins have no obvious catalytic or chaperone function. However, their hydrophilic properties suggest that they may play a role in structuring water. The structure of the proteins in aqueous environment will give better insights into the role of these proteins. In this paper we showed that the proteins are very unstructured in solution and this is consistent with a water-structuring function.
Technical Abstract: Group 1 late embryogensis-abundant (LEA) proteins are a subset of the hydrophilins , postulated to protect plant macromolecules from damage during freezing, desiccation and osmotic stresses. This paper documents the structure of a group 1 LEA protein from soybean. The protein exists mostly as a random coil in solution adopting some alpha helical structure when exposed to trifluoroethanol or sodium dodecyl sulfate, but not in the presence of phospholipids. Instead, about 14% of the amino acid residues exist in a solvent-exposed, left-handed extended helical or poly (L-proline)- type (PII) conformation at 20C. It is hypothesized that PII structure, not alpha helical or beta sheet structure, confers a high surface area of the protein so that it can interact with the aqueous solvent environment.