Studies of Single-Molecule Dynamics in Microorganisms
Fluorescence microscopy is one of the most extensively used techniques in the life sciences. Considering the non-invasive sample preparation, enabling live-cell compliant imaging, and the speciﬁc ﬂuorescence labeling, allowing for a speciﬁc visualization of virtually any cellular compound, it is pos...
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|Summary:||Fluorescence microscopy is one of the most extensively used techniques in the life sciences. Considering the non-invasive sample preparation, enabling live-cell compliant imaging, and the speciﬁc ﬂuorescence labeling, allowing for a speciﬁc visualization of virtually any cellular compound, it is possible to localize even a single molecule in living cells. This makes modern ﬂuorescence microscopy a powerful toolbox.
In the recent decades, the development of new, "super-resolution" ﬂuorescence microscopy techniques, which surpass the diﬀraction limit, revolutionized the ﬁeld. Single-Molecule Localization Microscopy (SMLM) is a class of super-resolution microscopy methods and it enables resolution of down to tens of nanometers. SMLM methods like Photoactivated Localization Microscopy (PALM), (direct) Stochastic Optical Reconstruction Microscopy ((d)STORM), Ground-State Depletion followed by Individual Molecule Return (GSDIM) and Point Accumulation for Imaging in Nanoscale Topography (PAINT) have allowed to investigate both, the intracellular spatial organization of proteins and to observe their real-time dynamics at the single-molecule level in live cells.
The focus of this thesis was the development of novel tools and strategies for live-cell SingleParticle Tracking PALM (sptPALM) imaging and implementing them for biological research. In the ﬁrst part of this thesis, I describe the development of new Photoconvertible Fluorescent Proteins (pcFPs) which are optimized for sptPALM lowering the phototoxic damage caused by the imaging procedure. Furthermore, we show that we can utilize them together with Photoactivatable Fluorescent Proteins (paFPs) to enable multi-target labeling and read-out in a single color channel, which signiﬁcantly simpliﬁes the sample preparation and imaging routines as well as data analysis of multi-color PALM imaging of live cells.
In parallel to developing new ﬂuorescent proteins, I developed a high throughput data analysis pipeline. I have implemented this pipeline in my second project, described in the second part of this thesis, where I have investigated the protein organization and dynamics of the CRISPR-Cas antiviral defense mechanism of bacteria in vivo at a high spatiotemporal level with the sptPALM approach. I was successful to show the diﬀerences in the target search dynamics of the CRISPR eﬀector complexes as well as of single Cas proteins for diﬀerent target complementarities. I have also ﬁrst data describing longer-lasting bound-times between eﬀector complex and their potential targets in vivo, for which only in vitro data has been available till today.
In summary, this thesis is a signiﬁcant contribution for both, the advances of current sptPALM imaging methods, as well as for the understanding of the native behavior of CRISPR-Cas systems in vivo.|
|Physical Description:||184 Pages|