Probing Single-Molecule Protein Spontaneous Folding–Unfolding Conformational Fluctuation Dynamics: The Multiple-State and Multiple-Pathway Energy Landscape

2015 ◽  
Vol 119 (21) ◽  
pp. 6366-6378 ◽  
Author(s):  
Zijian Wang ◽  
H. Peter Lu
Keyword(s):  
Single Molecule ◽  
Energy Landscape ◽  
Multiple Pathway ◽  
Multiple State ◽  
Conformational Fluctuation ◽  
Fluctuation Dynamics

scholarly journals Single-molecule spectroscopy reveals how calmodulin activates NO synthase by controlling its conformational fluctuation dynamics

2015 ◽  
Vol 112 (38) ◽  
pp. 11835-11840 ◽  
Author(s):  
Yufan He ◽  
Mohammad Mahfuzul Haque ◽  
Dennis J. Stuehr ◽  
H. Peter Lu
Keyword(s):  
Single Molecule ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Conformational States ◽  
Calmodulin Binding ◽  
Conformational Fluctuation ◽  
Fluctuation Dynamics ◽  
The Individual ◽  
Domain Motions ◽  
Oxide Synthase

Mechanisms that regulate the nitric oxide synthase enzymes (NOS) are of interest in biology and medicine. Although NOS catalysis relies on domain motions, and is activated by calmodulin binding, the relationships are unclear. We used single-molecule fluorescence resonance energy transfer (FRET) spectroscopy to elucidate the conformational states distribution and associated conformational fluctuation dynamics of the two electron transfer domains in a FRET dye-labeled neuronal NOS reductase domain, and to understand how calmodulin affects the dynamics to regulate catalysis. We found that calmodulin alters NOS conformational behaviors in several ways: It changes the distance distribution between the NOS domains, shortens the lifetimes of the individual conformational states, and instills conformational discipline by greatly narrowing the distributions of the conformational states and fluctuation rates. This information was specifically obtainable only by single-molecule spectroscopic measurements, and reveals how calmodulin promotes catalysis by shaping the physical and temporal conformational behaviors of NOS.

scholarly journals Slow domain reconfiguration causes power-law kinetics in a two-state enzyme

2018 ◽  
Vol 115 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Iris Grossman-Haham ◽  
Gabriel Rosenblum ◽  
Trishool Namani ◽  
Hagen Hofmann
Keyword(s):  
Free Energy ◽  
Single Molecule ◽  
Power Law ◽  
Energy Landscape ◽  
Rate Equations ◽  
Free Energy Landscape ◽  
Closed Domain ◽  
Single Molecule Fret ◽  
Power Law Kinetics ◽  
Interdomain Interactions

Protein dynamics are typically captured well by rate equations that predict exponential decays for two-state reactions. Here, we describe a remarkable exception. The electron-transfer enzyme quiescin sulfhydryl oxidase (QSOX), a natural fusion of two functionally distinct domains, switches between open- and closed-domain arrangements with apparent power-law kinetics. Using single-molecule FRET experiments on time scales from nanoseconds to milliseconds, we show that the unusual open-close kinetics results from slow sampling of an ensemble of disordered domain orientations. While substrate accelerates the kinetics, thus suggesting a substrate-induced switch to an alternative free energy landscape of the enzyme, the power-law behavior is also preserved upon electron load. Our results show that the slow sampling of open conformers is caused by a variety of interdomain interactions that imply a rugged free energy landscape, thus providing a generic mechanism for dynamic disorder in multidomain enzymes.

Single-molecule force spectroscopy reveals signatures of glassy dynamics in the energy landscape of ubiquitin

2006 ◽  
Vol 2 (4) ◽  
pp. 282-286 ◽  
Author(s):  
Jasna Brujić ◽  
Rodolfo I. Hermans Z. ◽  
Kirstin A. Walther ◽  
Julio M. Fernandez
Keyword(s):  
Single Molecule ◽  
Energy Landscape ◽  
Force Spectroscopy ◽  
Glassy Dynamics ◽  
Single Molecule Force Spectroscopy
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