Three-dimensional Single-molecule Microscopy of Bacterial Regulatory Proteins Within a Pole-localized Microdomain PDF Download

Author: Alex von Diezmann
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
Since the first optical detection of a single molecule 29 years ago, the development of single-molecule microscopy and spectroscopy has revolutionized the study of complex chemical systems. As reviewed in Chapter 1, by imaging and computationally localizing individual fluorescent dyes or proteins within a sample, their positions can be localized with typical precisions (10-40 nm) an order of magnitude or better than the optical diffraction limit of visible light (~250 nm laterally and ~500 nm axially). This technique is critical to super-resolution fluorescence microscopy and single-molecule tracking, which are now regularly used to measure the nanoscale structures, biomolecular motions, and stochastic chemical processes underlying the biology of cells. This dissertation comprises two intertwined single-molecule imaging projects: 1) optical and analytical methods development for three-dimensional (3D) single-molecule tracking and super-resolution microscopy, and 2) the application of these methods to understand the nanoscale organization and dynamics of proteins at the poles of the bacterium Caulobacter crescentus. Without modification, a single-molecule microscope only improves imaging resolution in the lateral (xy) dimension, but biological cells are intrinsically 3D. To improve the imaging resolution in z, the detection path of a standard widefield microscope can be modified using Fourier processing to encode z position in the pattern of light formed by each fluorescent emitter and detected on the camera. Chapter 2 reviews the development of a two-color 3D single-molecule microscope that uses the double-helix point spread function pattern to encode 3D position, while Chapter 3 describes how to correctly align and to calibrate the fine aberrations of such a microscope to achieve nanoscale imaging accuracy in multiple color channels simultaneously. The bacterium Caulobacter crescentus is a model organism for the study of cell polarization and asymmetric cell division. Chapters 4 and 5 describe work performed in collaboration with Prof. Lucy Shapiro and her laboratory in the Department of Developmental Biology in the Stanford University School of Medicine to study how the tips, or poles, of Caulobacter cells use proteins to act as nanoscale spatial landmarks that polarize cells and induce spatially organized development. The polar organizing protein PopZ is one such critical landmark, and Chapter 4 describes results obtained from 3D super-resolution imaging of PopZ. Such imaging showed that PopZ forms 150-200 nm space-filling polar microdomains of roughly uniform density, and that proteins of the chromosome partitioning machinery (ParA and ParB) exhibit different spatial behaviors (recruitment vs. tethering) relative to the PopZ microdomain depending on their biochemistry and role in the chromosome replication process. Chapter 5 discusses the combination of single-molecule tracking and super-resolution imaging to study the polar localization of the signaling molecules of that activate the master regulator protein CtrA. Precise 3D imaging and tracking showed that PopZ acts as a selectively permeable localization hub that slows the motion of signaling proteins. In combination with reaction-diffusion modeling and transcriptional assays, these microscopic measurements indicated that the PopZ microdomain acts to sequester the CtrA signaling pathway within the pole and spatially pattern transcriptional output within the predivisional Caulobacter cell.

Author: Camille Bayas
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
The first optical detection of a single molecule (SM) at cryogenic temperatures 30 years ago laid the groundwork for the routine detection of SMs today at biologically relevant temperatures, thus uncovering hidden heterogeneity that might be obscured by ensemble techniques. In addition to enabling studies of the intricate photochemistry and photophysics of fluorescent labels at the SM level, SM fluorescence has also proven useful for the imaging and tracking of cellular structures and biomolecules in a non-invasive manner with high sensitivity. The ability to genetically express fluorescent protein fusions in live cells has allowed specific labeling, and thus imaging and tracking, of dynamic processes and structures in cells. This dissertation describes applications of SM-based single-particle tracking (SPT) and super-resolution (SR) microscopy for the study of spatial organization and dynamics of bacterial proteins in two and three spatial dimensions. In an SPT experiment, the position of a SM emitter at very low concentration is measured over time to generate a trajectory, allowing for observation and quantification of labeled biomolecule dynamics at the SM level. In a SR microscopy experiment, the diffraction-limited (DL) resolution of a conventional fluorescence microscope (~200 nm in xy) is circumvented by temporally separating the emission of many SM emitters decorating a structure through control of their emissive state. A "super-resolved" image, with a factor of ~5-10 resolution improvement over a conventional DL fluorescence image, is generated by estimating the positions of many non-moving SM emitters over many frames and building up an image reconstruction in a pointillist manner. Chapter 1 of this dissertation provides an introduction to fluorescence, SM imaging, SM-based SR microscopy, and SPT. Chapter 1 also gives a brief introduction to Caulobacter crescentus, the bacterium used as the model organism in the SM studies in Chapters 4 and 5. Chapter 2 describes the experimental methods used to perform quantitative SM imaging of bacterial cells. The combination of SM imaging with point spread function (PSF) engineering has enabled the accurate and precise localization of SMs in three dimensions (3D) by the intentional introduction of specifically chosen aberrations in the emission path of an SM microscope. Throughout this dissertation, the double-helix (DH) PSF, a rotating PSF composed of two lobes whose angle encodes axial position, was used to estimate 3D SM positions. Chapter 2 describes the implementation of the DH-PSF via optical Fourier processing, and Chapter 3 describes the robust and comprehensible two-color Easy-DHPSF v2 software for localizing molecules in 3D and for registering localizations from two spectral channels into the same coordinate system with nanoscale accuracy. The resolution improvement gained from SM-based techniques is particularly useful for bacteria, the sizes of which are on the order of the DL. 3D SM-based SR and SPT have enabled the observation of structures and dynamics at length scales below the DL. Caulobacter is a useful biological target where understanding of the mechanisms for asymmetric cell division need to be explored and quantified. Central to Caulobacter's asymmetric division is the dynamic spatiotemporal regulation of gene expression and protein localization. Chapters 4 and 5 describes research performed in collaboration with Prof. Lucy Shapiro's laboratory (Department of Developmental Biology, Stanford School of Medicine) to study gene expression and signaling proteins in Caulobacter. Chapter 4 describes work studying the spatial organization and dynamics of ribosomes and a RNA-degrading enzyme RNase E using 3D SR microscopy and SPT. Results showed that the organization and dynamics of RNase E and ribosomes are closely related to the transcriptional activity of the cell. Finally, Chapter 5 describes SPT studies of the membrane-bound histidine kinase and stalked cell fate determinant DivJ in an effort to probe the physical properties of the Caulobacter stalked pole. Preliminary SPT results suggest that disrupting the physical properties and interactions at the stalked pole has an influence on DivJ diffusion and signaling.

Author: Marissa Kim Lee
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
Single molecules were first detected at low temperatures twenty-six years ago in the laboratory of W.E. Moerner. Subsequent technological advances have allowed researchers to study single molecules at room temperatures and within living cells, providing novel biological insight about underlying spatial and dynamical heterogeneity. By combining single molecule detection with the ability to control the emissive state of the fluorescent label (also called "active control"), a suite of super-resolution imaging techniques has been developed. These single-molecule-based super-resolution imaging strategies leverage the fluorescence microscope's ability to non-invasively study multiple targets within living cells, while bridging the resolution gap between optical and electron microscopies. In large part, future advances to improve single molecule and super-resolution imaging require better fluorophore and labeling technologies. Utilizing fluorophore with higher photon yields will increase the resolution of super-resolution images and the data acquisition speed. Additionally, a greater library fluorophores with different of colors and sensing capabilities will enable application to more imaging targets. Currently, many single molecule and super-resolution experiments within living systems use fluorescent proteins because the labeling of target proteins is more straightforward. However, the limited photon yield of fluorescent proteins often results in tantalizingly fuzzy super-resolution images. Imaging the same targets, labeled instead with brighter organic emitters, could provide more image detail, but better fluorogenic and genetically encoded labeling schemes must be developed and discovered. The first chapter of this dissertation will introduce and discuss the historical context and basic principles of single molecule and super-resolution imaging. Chapter 2 will then describe the general experimental procedures necessary for quantitative single molecule and super-resolution imaging, including quantifying the number of photons detected (and emitted) from a single molecule, as well as the preparation of bacterial samples for fluorescence microscopy. Later chapters apply these fundamental experimental measurements to study bacterial biology and fluorophore photophysics. Chapters 3 and 4 concern the development and characterization of organic emitters suitable for single molecule or super-resolution imaging, work achieved with the synthetic collaboration of organic chemists in the laboratory of Professor Robert J. Twieg at Kent State University. Chapter 3 discusses the optimization of rhodamine spirolactam photoswitching such that activation could occur at visible wavelengths. The optimized rhodamine spirolactams were then covalently attached to the surface of bacterial cells and imaged with three-dimensional super-resolution. Images of the bacterial cell surface demonstrates a marked improvement in labeling uniformity, specificity, and density compared to previous methods which labeled the surface with the transient binding of a membrane sensitive dye. Chapter 4 introduces a novel enzyme-based strategy to control the fluorescence from nitro-aryl fluorogens. A proof-of-principle experiment demonstrated that endogenous nitroreductase enzymes within bacterial cells could catalyze the fluorescence-activating reaction, thus generating free fluorophores, which were detectable on the single-molecule-level within the cell. Lastly, chapter 5 summarizes three-dimensional imaging experiments (performed in collaboration with the laboratory of Professor Lucy Shapiro in the Department of Developmental Biology at Stanford University) of components of the bacterial gene expression machinery labeled with fluorescent proteins. Super-resolution imaging is ideally suited to the small size scale of bacterial cells, and a wealth of biological insights remains to be discovered. Simultaneously improving fluorophore photon yield, specificity, and active control strategies will have a profound impact on super-resolution precision and speed.

Author: Lucy Shapiro
Publisher:
ISBN: 9780879699079
Category : Bacteria
Languages : en
Pages : 0

View

Book Description
Often thought to lack signifucant internal organization by comparison with eukaryotic cells, prokaryotes have in face been shown to possess distinct intracellular compartments. The book covers all aspects of prokaryotic cell biology, including the bacterial cytoskeleton, membrance organization, chromosome dynamics, nucleic acid processing and dynamics, as well as various methods.

Author: Peter Hinterdorfer
Publisher: Springer Science & Business Media
ISBN: 0387764976
Category : Science
Languages : en
Pages : 634

View

Book Description
This handbook describes experimental techniques to monitor and manipulate individual biomolecules, including fluorescence detection, atomic force microscopy, and optical and magnetic trapping. It includes single-molecule studies of physical properties of biomolecules such as folding, polymer physics of protein and DNA, enzymology and biochemistry, single molecules in the membrane, and single-molecule techniques in living cells.

Author:
Publisher: Elsevier
ISBN: 0128164646
Category : Science
Languages : en
Pages : 404

View

Book Description
Spectroscopy and Dynamics of Single Molecules: Methods and Applications reviews the most recent developments in spectroscopic methods and applications. Spectroscopic techniques are the chief experimental methods for testing theoretical models and research in this area plays an important role in stimulating new theoretical developments in physical chemistry. This book provides an authoritative insight into the latest advances in the field, highlighting new techniques, current applications, and potential future developments An ideal reference for chemists and physicists alike, Spectroscopy and Dynamics of Single Molecules: Methods and Applications is a useful guide for all those working in the research, design, or application of spectroscopic tools and techniques across a wide range of fields. - Includes the latest research on ultrafast vibrational and electronic dynamics, nonlinear spectroscopies, and single-molecule methods - Makes the content accessible to researchers in chemistry, biophysics, and chemical physics through a rigorous multi-disciplinary approach - Provides content edited by a world-renowned chemist with more than 30 years of experience in research and instruction

Author: Jose Antonio Morales-Gonzalez
Publisher: BoD – Books on Demand
ISBN: 953511123X
Category : Science
Languages : en
Pages : 516

View

Book Description
This work responds to the need to find, in a sole document, the affect of oxidative stress at different levels, as well as treatment with antioxidants to revert and diminish the damage. Oxidative Stress and Chronic Degenerative Diseases - a Role for Antioxidants is written for health professionals by researchers at diverse educative institutions (Mexico, Brazil, USA, Spain, Australia, and Slovenia). I would like to underscore that of the 19 chapters, 14 are by Mexican researchers, which demonstrates the commitment of Mexican institutions to academic life and to the prevention and treatment of chronic degenerative diseases.

Author: Walid El-Sharoud
Publisher: Springer Science & Business Media
ISBN: 3540749217
Category : Science
Languages : en
Pages : 377

View

Book Description
The application of new molecular methodologies in the study of bacterial behavior and cell architecture has enabled new revolutionary insights and discoveries in these areas. This new text presents recent developments in bacterial physiology that are highly relevant to a wide range of readership including those interested in basic and applied knowledge. Its chapters are written by international scientific authorities at the forefront of the subject. The value of this recent knowledge in bacterial physiology is not only restricted to fundamental biology. It also extends to biotechnology and drug-discovery disciplines.

Author: Vladimir Uversky
Publisher: John Wiley & Sons
ISBN: 0470618310
Category : Science
Languages : en
Pages : 532

View

Book Description
This book provides up-to-date information on experimental and computational characterization of the structural and functional properties of viral proteins, which are widely involved in regulatory and signaling processes. With chapters by leading research groups, it features current information on the structural and functional roles of intrinsic disorders in viral proteomes. It systematically addresses the measles, HIV, influenza, potato virus, forest virus, bovine virus, hepatitis, and rotavirus as well as viral genomics. After analyzing the unique features of each class of viral proteins, future directions for research and disease management are presented.

Author: Jozef Šamaj
Publisher: Springer Science & Business Media
ISBN: 3642324622
Category : Science
Languages : en
Pages : 337

View

Book Description
Endocytosis is a fundamental cellular process by means of which cells internalize extracellular and plasma membrane cargos for recycling or degradation. It is important for the establishment and maintenance of cell polarity, subcellular signaling and uptake of nutrients into specialized cells, but also for plant cell interactions with pathogenic and symbiotic microbes. Endocytosis starts by vesicle formation at the plasma membrane and progresses through early and late endosomal compartments. In these endosomes cargo is sorted and it is either recycled back to the plasma membrane, or degraded in the lytic vacuole. This book presents an overview of our current knowledge of endocytosis in plants with a main focus on the key molecules undergoing and regulating endocytosis. It also provides up to date methodological approaches as well as principles of protein, structural lipid, sugar and microbe internalization in plant cells. The individual chapters describe clathrin-mediated and fluid-phase endocytosis, as well as flotillin-mediated endocytosis and internalization of microbes. The book was written for a broad spectrum of readers including students, teachers and researchers.