Signal transduction in the visual system involves a series of proteins that are sequentially activated via protein-protein interactions, thus passing the signal from the membrane receptor to a final target. The long- term objectives of this project are to elucidate the molecular mechanisms of activation and signal propagation in three proteins of the relay: rhodopsin, transducin and arrestin. It is now abundantly clear that these proteins are highly "flexible". The flexibility involves ps-ns backbone fluctuations as well as a slower exchange between distinct conformational substates, both being central to function. Thus, mechanisms will not be revealed by structures determined in the confines of a crystal lattice, but will require new spectroscopic methods to complement crystallography and observe the proteins "in action" in a native-like environment. Toward this goal, one specific aim includes the development and application of new strategies in Site Directed Spin Labeling (SDSL). These include: (1) genetically encoded non-native amino acids for extending SDSL to previously inaccessible proteins and for attaching proteins to solid supports;(2) high pressure Electron Paramagnetic Resonance (EPR) for revealing protein flexibility and low-lying excited states and (3) pulse saturation recovery EPR and pressure-jump relaxation EPR for identifying conformational exchange and measuring exchange rates. Another specific aim is focused on application of these novel technologies together with Double Electron Electron Resonance (DEER) to elucidate structure and the role of dynamics in the activation of the proteins of signal transduction. Goals include a description of: (1) the conformational substates in activated rhodopsin (R*) and the mechanism of constitutive activation;(2) the conformational states of the transducin a-subunit and the structure of the R*-transducin complex and (3) the structure of the R*-arrestin complex, the transformations leading to the high-affinity binding form, and the mechanism of constitutive activation. A growing number of pathological conditions have been traced to genetic defects in the molecular switches of the visual and other signaling systems. In order to design pharmacological approaches for altering such pathological states, it is imperative to understand molecular mechanism involved in the signal relay. Success in this project is anticipated to contribute to this understanding.
A growing number of pathological conditions have been traced to defects in proteins involved in biological signaling. In order to design drugs to effectively correct the defect, it is imperative to understand how the proteins function. Success in this project will contribute substantially to this understanding.
|Yang, Zhongyu; Jiménez-Osés, Gonzalo; López, Carlos J et al. (2014) Long-range distance measurements in proteins at physiological temperatures using saturation recovery EPR spectroscopy. J Am Chem Soc 136:15356-65|
|Lerch, Michael T; Yang, Zhongyu; Brooks, Evan K et al. (2014) Mapping protein conformational heterogeneity under pressure with site-directed spin labeling and double electron-electron resonance. Proc Natl Acad Sci U S A 111:E1201-10|
|Schredelseker, Johann; Paz, Aviv; López, Carlos J et al. (2014) High resolution structure and double electron-electron resonance of the zebrafish voltage-dependent anion channel 2 reveal an oligomeric population. J Biol Chem 289:12566-77|
|Chen, Qiuyan; Zhuo, Ya; Kim, Miyeon et al. (2014) Self-association of arrestin family members. Handb Exp Pharmacol 219:205-23|
|Toledo Warshaviak, Dora; Khramtsov, Valery V; Cascio, Duilio et al. (2013) Structure and dynamics of an imidazoline nitroxide side chain with strongly hindered internal motion in proteins. J Magn Reson 232:53-61|
|Lopez, Carlos J; Yang, Zhongyu; Altenbach, Christian et al. (2013) Conformational selection and adaptation to ligand binding in T4 lysozyme cavity mutants. Proc Natl Acad Sci U S A 110:E4306-15|
|Song, Xiufeng; Seo, Jungwon; Baameur, Faiza et al. (2013) Rapid degeneration of rod photoreceptors expressing self-association-deficient arrestin-1 mutant. Cell Signal 25:2613-24|
|Vishnivetskiy, Sergey A; Chen, Qiuyan; Palazzo, Maria C et al. (2013) Engineering visual arrestin-1 with special functional characteristics. J Biol Chem 288:3394-405|
|Razzaghi, Sahand; Brooks, Evan K; Bordignon, Enrica et al. (2013) EPR relaxation-enhancement-based distance measurements on orthogonally spin-labeled T4-lysozyme. Chembiochem 14:1883-90|
|Garbuio, Luca; Bordignon, Enrica; Brooks, Evan K et al. (2013) Orthogonal spin labeling and Gd(III)-nitroxide distance measurements on bacteriophage T4-lysozyme. J Phys Chem B 117:3145-53|
Showing the most recent 10 out of 61 publications