A supplement to: NIGMS 1R15GM144907-01A1 - Polymer-Lipid Particles
investigated by Magnetic Resonance Spectroscopy
In response to: PA-20-272 - Administrative Supplements to Existing NIH Grants and
Cooperative Agreements (Parent Admin Supp Clinical Trial Optional)
Funds are requested from NIGMS to obtain state of the art gel permeation
chromatography (GPC) multi-angle light scattering (MALS) equipment to facilitate
polymer analysis. Development of novel polymers is integral to NIGMS 1R15GM144907-
01A1, therefore having reliable methods for characterizing the polymers is essential to
the project. Funds are being requested to obtain a TOSOH EcoSEC Elite including
Refractive Index and LenS3 Multi-Angle Light Scattering Detector GPC MALS system
capable of efficient and accurate polymer analysis to replace equipment that is from 2014.
Project Summary/Abstract: Membrane proteins represent approximately 30% of all
known proteins but only approximately 1% of solved protein structures. Despite recent
advances in methods for membrane protein structural biology, knowledge about this
important class of proteins lags behind their soluble counterparts. Membrane proteins are
critical to numerous aspects of health, ranging from regulation cellular function and
transport into and out of the cell, through to viral infections which use membrane proteins
as part of the infection cycle. In almost 90% of newly developed and approved
therapeutics, protein structural information was used to guide the development of the
therapeutic molecules. Due to the limited and incomplete structural information on
membrane proteins, the development of therapeutics and treatments that target
membrane bound proteins is limited. A challenge in elucidating membrane protein
structures is the lack of robust and appropriate lipid membrane mimetics. Existing
membrane mimetics have limitations that can hinder membrane protein structural
determination. This highlights an urgent need to develop lipid membrane mimetics which
both provide a good approximation to the native lipid bilayer in terms of both structure
and curvature, while also facilitating structural analysis of the membrane protein
embedded in the mimetic. Yet polymer structure-function relationships are not well
established for polymers that interact with lipids and membrane proteins.
This project will use modern controlled polymer chemistry tools, to create a new class
of polymers that will self-assemble with lipids. These self-assembled polymer-lipid
systems will form well defined discs on the order of 10s of nanometers, giving lipid
membrane mimetics suitable for the analysis of many membrane proteins. The advanced
polymer chemistry techniques will enable fine tuning of polymer’s length, charges, and
hydrophobicity. Polymer analysis through GPC MALS will give detailed information on the
polymer’s properties, facilitation structure -function relationships between polymers and
their self-assembled structures. Polymers will also be modified with spin-labels for
electron paramagnetic resonance spectroscopy. Electron paramagnetic resonance
spectroscopy methods will be used on polymers, lipids and membrane proteins modified
with appropriate spin labels, providing insights into the local dynamics and proximities of
the self-assembled polymer-lipid and polymer-lipid-membrane protein complexes. These
insights can be used to guide the design of polymers for robust lipid membrane mimetics.
Training and mentoring of undergraduate students as well as a graduate assistant will
be a core feature of the proposed project. Undergraduate students will be integrated fully
into the projects, including the polymer analysis, along with the graduate student, gaining
skills in this field at the interface of materials science and biophysics.
