Amino Acids, Peptides, and Proteins; Eye Diseases; Hormones, Hormone Substitutes, and Hormone Antagonists; Chemical Actions and Uses; Macromolecular Substances
Biochemistry, Biophysics and Structural Biology: Cell Cycle and Signal Transduction | Protein Folding, Dynamics and Degradation
Extensive Research Description
(1) Amyloid Aggregation on Cell membrane
The misfolding of amyloid proteins on cell membrane is associated with the onset of amyloid diseases. However, the investigation is challenging due to a lack of methods that allows direct observation of changes in protein secondary structures on membrane surfaces without using molecular labels. We develop a surface-specific vibrational spectroscopic method, chiral sum frequency generation. The method has enabled us to observe in situ and in real time the misfolding of amyloid proteins from disordered structures to ?lpha-helices and then beta-sheets on membrane surface. The results provide insight into the pathogenic mechanism and rational drug design.
(2) GPCR Signal Transduction across Cell Membrane
Seven-alpha-helical transmembrane G protein-coupled receptors (GPCRs) belong to the largest gene family in the human genome and represent important drug targets. We use nanodiscs to purify GPCRs and unnatural amino acid mutagenesis to site-specifically label GPCRs. Then, we exploit methods in biophysical spectroscopy to obtain highly selective spectroscopic readouts to report conformational changes of GPCRs during activation. The results will reveal the activation mechanism of GPCRs at the molecular level, guiding rational drug design targeting GPCRs.
(3) Transmembrane Visual Pigments in Molecular Mechanism of Vision
GPCR rhodopsin is a very sensitive biological light detector with extremely low dark noise. We aim to understand the molecular basis of its low dark noise level. The results will provide a strong basis to understand inherited eye diseases caused by mutations in the rhodopsin gene leading to retinitis pigmentosa, a family of progressive retinal degenerative diseases. The studies will also provide insight into molecular evolution of vertebrate vision, revealing the molecular mechanism in the divergence of cone pigments to rod pigments in the development of vertebrate dim-light vision.
- Liu, M.Y.; Liu, J.; Mehrotra, D.; Liu, Y.; Guo, Y.; Baldera-Aguayo, P.A.; Mooney, V; Nour, A.M.; Yan, E.C.Y. “Thermal Stability of Rhodopsin and Progression of Retinitis Pigmentosa: A Comparison of S186W and D190N Rhodopsin Mutants” In press, J. Biol. Chem. 2013
- Fu, L.; Xiao, D.Q.; Wang, Z.; Batista, V. S.; Yan, E.C.Y. “Chiral Sum Frequency Generation for Probing the Hydrogen/Deuterium Exchange in Antiparallel beta-Sheet Peptides at Interfaces” J. Am. Chem. Soc. 135, 3592, 2013
- Mitra, N.; Liu, Y.; Liu, J.; Serebryany, E.; Mooney, V.; DeVree, B.T.; Sunahara, R.; Yan, E.C.Y. “Calcium Dependent Ligand Binding and G-protein Signaling of Family B GPCR Parathyroid Hormone 1 Receptor Purified in Nanodiscs” ACS Chem. Biol. 8, 617, 2013
- Fu, L.; Liu, J.; Yan, E.C.Y. “Chiral Sum Frequency Generation for Identification of Protein Secondary Structures at Interfaces” J. Am. Chem. Soc. 133, 8094, 2011
- Fu, L.; Ma, G.; Yan, E.C.Y. “In Situ Misfolding of Human Islet Amyloid Polypeptide at Interfaces Probed by Sum Frequency Generation Spectroscopy” J. Am. Chem. Soc. 132, 5405, 2010
- Serebryany, E.; Zhu, G.F.; Fu, L.; Liu, J.; Yan, E.C.Y. “Artificial Membrane-like Environments for In Vitro Studies of Purified G-protein Coupled Receptors” Invited Review, BBA-Biomembrane, 1818, 225, 2011