Single-Molecule Spectroscopy Study of Crowding-Induced Protein Spontaneous Denature and Crowding-Perturbed Unfolding–Folding Conformational Fluctuation Dynamics

2018 ◽  
Vol 122 (26) ◽  
pp. 6724-6732 ◽  
Author(s):  
Zijiang Wang ◽  
H. Peter Lu
Keyword(s):  
Single Molecule ◽  
Single Molecule Spectroscopy ◽  
Spectroscopy Study ◽  
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.

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