This project is aimed at the study of the properties of membrane proteins that underlie important biomedical processes and/or are implicated in health disorders and how they interact with their membrane environments. By means of the latest one and two-dimensional electron-spin resonance (ESR) methodologies and nitroxide spin-labeling methods, we will directly observe significant protein functional changes, and in parallel experiments observe the changes occurring in the dynamic structure of the membrane lipids. This ability to accurately characterize both membrane host and membrane protein is an innovative approach in this project on the role of membrane-protein interactions in the protein's function. Specific projects include the following: Study of the effect of fusion peptides and transmembrane domains on membranes will be continued. Recent results showed that the influenza hemagglutinin (HA) fusion peptide (FP) cooperatively increases ordering of the membrane headgroup region. To determine if this membrane ordering effect is common for other entry of envelope viruses, the effect of HIV gp41 fusion peptide and Ebolavirus internal fusion loop will be studied, including their aggregation. In the second project on the dynamics of antigen-mediated clustering of Immunoglobulin E (IgE)-receptor (FceRI) complexes in membranes, it will be determined how protein-lipid and protein- protein interactions dictate their first steps. This study will build upon our recent successes in developing ESR methods to characterize the changes in membrane structural dynamics upon activation. In a third project, tau, a protein important in neurodegeneration will be studied. The molecular basis for tau interactions (and of its disease-linked mutations) with membranes will be addressed. These studies will benefit from our successful project on another intrinsically disordered protein, alpha synuclein. A fourth project will be directed to deter- mine the effects of bilayer properties on th functional dynamics of the glutamate transporter GltPh, an archael homologue of mammalian glutamate transporters, building on recent ESR studies in these labs. In a fifth project our recent ESR studies on the mechanism of transmembrane signaling in bacterial chemoreceptors will be continued and extended. In particular, the participation of membrane lipids will be addressed, including how the bilayer itself changes upon receptor activation, as well as the concomitant changes within the receptors. In all these studies, the modern ESR techniques of Pulse-Dipolar ESR (PDS) (which includes both double electron-electron resonance (DEER) and Double Quantum Coherence (DQC)-ESR) will be used to characterize membrane protein functional changes, and the techniques of multi-frequency ESR and Two-Dimensional Electron-Electron Double Resonances (2D-ELDOR) will be utilized to characterize the concomitant changes in dynamic structure of the membranes. These studies will involve extensive collaborations with leading research groups. Possible clinical applications include detection of membrane changes during immune response, prevention of viral entry, neurological disorders, and development of anti-microbials.
We are studying structures of proteins and cell membranes, as well as the way proteins interact with other components of cell membranes, such as lipids and cholesterols. Our study will focus on understanding mechanisms by which cells communicate with each other through exchange of cellular components. Disorder in the structure of the proteins and the manner of cell communication may lead to allergic conditions, Alzheimer's and other neurodegenerative diseases, viral and bacterial diseases.
|Lai, Alex L; Millet, Jean K; Daniel, Susan et al. (2017) The SARS-CoV Fusion Peptide Forms an Extended Bipartite Fusion Platform that Perturbs Membrane Order in a Calcium-Dependent Manner. J Mol Biol 429:3875-3892|
|Pinello, Jennifer Fricke; Lai, Alex L; Millet, Jean K et al. (2017) Structure-Function Studies Link Class II Viral Fusogens with the Ancestral Gamete Fusion Protein HAP2. Curr Biol 27:651-660|
|Snead, David; Lai, Alex L; Wragg, Rachel T et al. (2017) Unique Structural Features of Membrane-Bound C-Terminal Domain Motifs Modulate Complexin Inhibitory Function. Front Mol Neurosci 10:154|
|Sukomon, Nattakan; Widom, Joanne; Borbat, Peter P et al. (2017) Stability and Conformation of a Chemoreceptor HAMP Domain Chimera Correlates with Signaling Properties. Biophys J 112:1383-1395|
|Lai, Alex L; Clerico, Eugenia M; Blackburn, Mandy E et al. (2017) Key features of an Hsp70 chaperone allosteric landscape revealed by ion-mobility native mass spectrometry and double electron-electron resonance. J Biol Chem 292:8773-8785|
|Samanta, Dipanjan; Widom, Joanne; Borbat, Peter P et al. (2016) Bacterial Energy Sensor Aer Modulates the Activity of the Chemotaxis Kinase CheA Based on the Redox State of the Flavin Cofactor. J Biol Chem 291:25809-25814|
|Georgieva, Elka R; Borbat, Peter P; Grushin, Kirill et al. (2016) Conformational Response of Influenza A M2 Transmembrane Domain to Amantadine Drug Binding at Low pH (pH 5.5). Front Physiol 7:317|
|Lai, Alex L; Freed, Jack H (2015) The Interaction between Influenza HA Fusion Peptide and Transmembrane Domain Affects Membrane Structure. Biophys J 109:2523-36|
|Samanta, Dipanjan; Borbat, Peter P; Dzikovski, Boris et al. (2015) Bacterial chemoreceptor dynamics correlate with activity state and are coupled over long distances. Proc Natl Acad Sci U S A 112:2455-60|
|Orlando, Benjamin J; Borbat, Peter P; Georgieva, Elka R et al. (2015) Pulsed Dipolar Spectroscopy Reveals That Tyrosyl Radicals Are Generated in Both Monomers of the Cyclooxygenase-2 Dimer. Biochemistry 54:7309-12|
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