Nanoscale Analysis of the Effect of Pathogenic Mutations on Polycystin-1

2010 ◽  
Author(s):  
Liang Ma ◽  
Meixiang Xu ◽  
Andres F. Oberhauser
Keyword(s):  
Single Molecule ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Structure And Function ◽  
Eukaryotic Cells ◽  
Mechanical Forces ◽  
Force Microscopy ◽  
Physiological Conditions ◽  
Atomic Force ◽  
And Function

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).

The structure and function of cell membranes examined by atomic force microscopy and single-molecule force spectroscopy

2015 ◽  
Vol 44 (11) ◽  
pp. 3617-3638 ◽  
Author(s):  
Yuping Shan ◽  
Hongda Wang
Keyword(s):  
Atomic Force Microscopy ◽  
Single Molecule ◽  
Cell Membranes ◽  
Force Spectroscopy ◽  
Structure And Function ◽  
Single Molecule Force Spectroscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
And Function

The structure and function of cell membranes were revealed by atomic force microscopy and force spectroscopy at the molecule level.

Structure and Function of Ion Pumps Studied by Atomic Force Microscopy and Gene-transfer Experiments Using Chimeric Na+/K+- and Ca2+ ATPases

1994 ◽  
pp. 264-275
Author(s):  
Kunio Takeyasu ◽  
Jose K. Paul ◽  
Mehdi Ganjeizadeh ◽  
M. Victor Lemas ◽  
Shusheng Wang ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Gene Transfer ◽  
Structure And Function ◽  
Ion Pumps ◽  
Force Microscopy ◽  
Atomic Force ◽  
And Function

scholarly journals How Microbes Use Force To Control Adhesion

2020 ◽  
Vol 202 (12) ◽  
Author(s):  
Albertus Viljoen ◽  
Johann Mignolet ◽  
Felipe Viela ◽  
Marion Mathelié-Guinlet ◽  
Yves F. Dufrêne
Keyword(s):  
Single Molecule ◽  
Molecular Mechanisms ◽  
Flow Chamber ◽  
Microbial Adhesion ◽  
Single Molecule Level ◽  
Force Microscopy ◽  
Atomic Force ◽  
Adhesive Interactions ◽  
And Function ◽  
Mechanisms Of Adhesion

ABSTRACT Microbial adhesion and biofilm formation are usually studied using molecular and cellular biology assays, optical and electron microscopy, or laminar flow chamber experiments. Today, atomic force microscopy (AFM) represents a valuable addition to these approaches, enabling the measurement of forces involved in microbial adhesion at the single-molecule level. In this minireview, we discuss recent discoveries made applying state-of-the-art AFM techniques to microbial specimens in order to understand the strength and dynamics of adhesive interactions. These studies shed new light on the molecular mechanisms of adhesion and demonstrate an intimate relationship between force and function in microbial adhesins.

scholarly journals Single-molecule observation of nucleotide induced conformational changes in basal SecA-ATP hydrolysis

2018 ◽  
Vol 4 (10) ◽  
pp. eaat8797 ◽  
Author(s):  
Nagaraju Chada ◽  
Kanokporn Chattrakun ◽  
Brendan P. Marsh ◽  
Chunfeng Mao ◽  
Priya Bariya ◽  
...  
Keyword(s):  
Single Molecule ◽  
Conformational Changes ◽  
Atp Hydrolysis ◽  
Conformational Dynamics ◽  
Real Space ◽  
Biochemical Activity ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reversible Transitions ◽  
Space Measurement

SecA is the critical adenosine triphosphatase that drives preprotein transport through the translocon, SecYEG, in Escherichia coli. This process is thought to be regulated by conformational changes of specific domains of SecA, but real-time, real-space measurement of these changes is lacking. We use single-molecule atomic force microscopy (AFM) to visualize nucleotide-dependent conformations and conformational dynamics of SecA. Distinct topographical populations were observed in the presence of specific nucleotides. AFM investigations during basal adenosine triphosphate (ATP) hydrolysis revealed rapid, reversible transitions between a compact and an extended state at the ~100-ms time scale. A SecA mutant lacking the precursor-binding domain (PBD) aided interpretation. Further, the biochemical activity of SecA prepared for AFM was confirmed by tracking inorganic phosphate release. We conclude that ATP-driven dynamics are largely due to PBD motion but that other segments of SecA contribute to this motion during the transition state of the ATP hydrolysis cycle.

scholarly journals Single-molecule measurements reveal that PARP1 condenses DNA by loop formation

2020 ◽  
Author(s):  
Nicholas A. W. Bell ◽  
Philip J. Haynes ◽  
Katharina Brunner ◽  
Taiana Maia de Oliveira ◽  
Maria Flocco ◽  
...  
Keyword(s):  
Dna Damage ◽  
Atomic Force Microscopy ◽  
Dna Repair ◽  
Single Molecule ◽  
Parp Inhibitors ◽  
Magnetic Tweezers ◽  
Mechanical Forces ◽  
Loop Formation ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTPoly(ADP-ribose) polymerase 1 (PARP1) is an abundant nuclear enzyme that plays important roles in DNA repair, chromatin organization and transcription regulation. Although binding and activation of PARP1 by DNA damage sites has been extensively studied, little is known about how PARP1 binds to long stretches of undamaged DNA and how it could shape chromatin architecture. Here, using a combination of single-molecule techniques including magnetic tweezers and atomic force microscopy, we show that PARP1 binds and condenses undamaged, kilobase-length DNA subject to sub-picoNewton mechanical forces. Decondensation by high force proceeds through a series of discrete increases in extension, indicating that PARP1 stabilizes loops of DNA. This model is supported by DNA braiding experiments which show that PARP1 can bind at the intersection of two separate DNA molecules. PARP inhibitors do not affect the level of condensation of undamaged DNA, but act to block condensation reversal for damaged DNA in the presence of NAD+. Our findings establish a mechanism for PARP1 in the organization of chromatin structure.

Characterization of Erythrocytes in the Sickle Cell Trait

2011 ◽  
Vol 1301 ◽  
Author(s):  
Jamie L. Maciaszek ◽  
George Lykotrafitis
Keyword(s):  
Sickle Cell ◽  
Single Molecule ◽  
Protein Interactions ◽  
Sickle Cell Trait ◽  
Human Subjects ◽  
Protein Protein Interactions ◽  
Force Microscopy ◽  
Laminin Receptors ◽  
Atomic Force ◽  
Normal Human

ABSTRACTAtomic force microscopy (AFM) allows for high-resolution topography studies of biological cells, measurement of their mechanical properties, and quantification of protein-protein interactions in physiological conditions. In this work, AFM was employed to investigate morphological, material, and chemomechanical properties of red blood cells from human subjects with sickle cell trait. We measured the stiffness of the cells and demonstrated that the Young’s modulus of pathological erythrocytes was three times greater than in normal cells. A single molecule AFM method was employed to report that erythrocytes from human subjects with the sickle cell trait express a greater number of the laminin receptors BCAM/Lu (p < 0.05) than erythrocytes from normal human subjects. Observed differences indicate the effect of sickle hemoglobin in the erythrocyte and possible changes in the organization of the cell cytoskeleton and membrane proteins associated with the sickle cell trait.

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