Electrostatic Roles on Macromolecular Assemblies in Vision Processes

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

NON-TECHNICAL SUMMARY The ability to see is the interface between a human and the rest of his/her universe. This ability is often hampered by malfunctioning of macromolecules and their assemblies which make up several compartments of human eye. Examples include crystallin proteins in human lens and hyaluronic acid-collagen composite gel in the vitreous of human eye. Despite the enormous significance of knowing how these charged macromolecules behave in the human eye, a fundamental understanding is lacking. The challenge arises from variations in the sequences of the crystallin proteins and how they interact among themselves via a combination of hydrophobic and electrostatic interactions. In the case of vitreous, how the collagen molecules organize into fibers inside a restrictive gel-like environment created by hyaluronic acid matrix, is a new area for quantitative and fundamental investigation. The Principal Investigator proposes to use a combination of synthesis, including site-directed mutagenesis and chemical synthesis, computer modeling, characterization techniques using light scattering, microscopy, and rheology, and advanced polymer physics theories. One of the major components of the proposed research is to mentor and build scientific foundation for the next generation of scientists to pursue fundamental research in an area of tremendous importance in getting rid of human blindness. TECHNICAL SUMMARY Experiments and modeling are proposed to understand the aggregation/disaggregation of crystallin proteins pertinent to human lens, and the assembly of collagen bundles in hyaluronic acid matrixes pertinent to human vitreous, using site-directed mutageneis, chemical synthesis, static and dynamic light scattering, differential dynamic microscopy, rheology, and computer modeling. Specifically, the proposal addresses (i) role of crystallin protein sequences (synthesized by site-directed mutagenesis) on aggregation, (ii) role of charge modification of crystallin proteins on aggregation/disaggregation, (iii) nucleation and growth of collagen bundles, and (iv) extent of heterogeneous distribution of collagen bundles inside hyaluronic acid matrix. The proposed work aims at identifying fundamental principles behind aggregation of large numbers of protein molecules in aqueous crowded environments, based on conformational fluctuations and controllable modulations of electrostatic forces. The proposed in vitro experiments will result in insights on the macromolecular origins for required transparency to light in human eye. Training students in this interdisciplinary area with a strong focus on fundamental understanding is the strong educational component of the proposed activity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.