Correlating Structure and Function in Organic Electronics: From Single Molecule Transport to Singlet Fission

The activity of proteins and their complexes often involves the conversion of chemical energy (stored or supplied) into mechanical work through conformational changes. Mechanical forces are also crucial for the regulation of the structure and function of cells and tissues. Thus, the shape of eukaryotic cells is the result of cycles of mechano-sensing, mechano-transduction, and mechano-response. Recently developed single-molecule atomic force microscopy (AFM) techniques can be used to manipulate single molecules, both in real time and under physiological conditions, and are ideally suited to directly quantify the forces involved in both intra- and intermolecular protein interactions. In combination with molecular biology and computer simulations, these techniques have been applied to characterize the unfolding and refolding reactions in a variety of proteins, such as titin (an elastic mechano-sensing protein found in muscle) and polycystin-1 (PC1, a mechanosensor found in the kidney).

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Single-molecule Observations of Replisome Structure and Function

Biophysical Journal ◽

10.1016/j.bpj.2008.12.3655 ◽

2009 ◽

Vol 96 (3) ◽

pp. 556a-557a

Author(s):

Joseph J. Loparo ◽

Samir M. Hamdan ◽

Charles C. Richardson ◽

M. van Antoine Oijen

Keyword(s):

Single Molecule ◽

Structure And Function ◽

And Function

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Evaluating RNA Structural Flexibility: Viruses Lead the Way

Viruses ◽

10.3390/v13112130 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2130

Author(s):

Connor W. Fairman ◽

Andrew M. L. Lever ◽

Julia C. Kenyon

Keyword(s):

Structural Analysis ◽

Single Molecule ◽

Rna Structure ◽

Conformational Flexibility ◽

Structure And Function ◽

Structural Flexibility ◽

Productive Area ◽

Biophysical Techniques ◽

Biological Polymers ◽

And Function

Our understanding of RNA structure has lagged behind that of proteins and most other biological polymers, largely because of its ability to adopt multiple, and often very different, functional conformations within a single molecule. Flexibility and multifunctionality appear to be its hallmarks. Conventional biochemical and biophysical techniques all have limitations in solving RNA structure and to address this in recent years we have seen the emergence of a wide diversity of techniques applied to RNA structural analysis and an accompanying appreciation of its ubiquity and versatility. Viral RNA is a particularly productive area to study in that this economy of function within a single molecule admirably suits the minimalist lifestyle of viruses. Here, we review the major techniques that are being used to elucidate RNA conformational flexibility and exemplify how the structure and function are, as in all biology, tightly linked.

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The yeast dynein Dyn2-Pac11 complex is a dynein dimerization/processivity factor: structural and single-molecule characterization

Molecular Biology of the Cell ◽

10.1091/mbc.e13-03-0166 ◽

2013 ◽

Vol 24 (15) ◽

pp. 2362-2377 ◽

Cited By ~ 19

Author(s):

Lu Rao ◽

Erin M. Romes ◽

Matthew P. Nicholas ◽

Sibylle Brenner ◽

Ashutosh Tripathy ◽

...

Keyword(s):

Crystal Structure ◽

Saccharomyces Cerevisiae ◽

Motor Activity ◽

Single Molecule ◽

Cytoplasmic Dynein ◽

Structure And Function ◽

Processivity Factor ◽

Molecular Effects ◽

And Function ◽

Motor Element

Cytoplasmic dynein is the major microtubule minus end–directed motor. Although studies have probed the mechanism of the C-terminal motor domain, if and how dynein's N-terminal tail and the accessory chains it binds regulate motor activity remain to be determined. Here, we investigate the structure and function of the Saccharomyces cerevisiae dynein light (Dyn2) and intermediate (Pac11) chains in dynein heavy chain (Dyn1) movement. We present the crystal structure of a Dyn2-Pac11 complex, showing Dyn2-mediated Pac11 dimerization. To determine the molecular effects of Dyn2 and Pac11 on Dyn1 function, we generated dyn2Δ and dyn2Δpac11Δ strains and analyzed Dyn1 single-molecule motor activity. We find that the Dyn2-Pac11 complex promotes Dyn1 homodimerization and potentiates processivity. The absence of Dyn2 and Pac11 yields motors with decreased velocity, dramatically reduced processivity, increased monomerization, aggregation, and immobility as determined by single-molecule measurements. Deleting dyn2 significantly reduces Pac11-Dyn1 complex formation, yielding Dyn1 motors with activity similar to Dyn1 from the dyn2Δpac11Δ strain. Of interest, motor phenotypes resulting from Dyn2-Pac11 complex depletion bear similarity to a point mutation in the mammalian dynein N-terminal tail (Loa), highlighting this region as a conserved, regulatory motor element.

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Single-particle virology

Biophysical Reviews ◽

10.1007/s12551-020-00747-9 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1141-1154 ◽

Cited By ~ 3

Author(s):

Bálint Kiss ◽

Dorottya Mudra ◽

György Török ◽

Zsolt Mártonfalvi ◽

Gabriella Csík ◽

...

Keyword(s):

Optical Tweezers ◽

Single Molecule ◽

Single Particle ◽

Structure And Function ◽

Scanning Probe ◽

Direct Access ◽

Viral Diseases ◽

Biomolecular Structure ◽

And Function ◽

Individual Particles

Abstract The development of advanced experimental methodologies, such as optical tweezers, scanning-probe and super-resolved optical microscopies, has led to the evolution of single-molecule biophysics, a field of science that allows direct access to the mechanistic detail of biomolecular structure and function. The extension of single-molecule methods to the investigation of particles such as viruses permits unprecedented insights into the behavior of supramolecular assemblies. Here we address the scope of viral exploration at the level of individual particles. In an era of increased awareness towards virology, single-particle approaches are expected to facilitate the in-depth understanding, and hence combating, of viral diseases.

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