Enzyme-mediated Labeling of Proteins and Protein-protein Interactions in Vitro and in Living Cells - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Enzyme-mediated Labeling of Proteins and Protein-protein Interactions in Vitro and in Living Cells write by Sarah Ann Slavoff. This book was released on 2010. Enzyme-mediated Labeling of Proteins and Protein-protein Interactions in Vitro and in Living Cells available in PDF, EPUB and Kindle. The E. coli biotin ligase enzyme, BirA, has been previously used by the Ting research group for site-specific labeling of peptide-tagged cell surface proteins. We sought to expand the utility of biotin ligase-mediated labeling to functional group handles, including azides and alkynes, for bio-orthogonal chemistry. Since the BirA and its point mutants were unable to ligate these probes to an acceptor peptide, we screened biotin ligases from multiple species to identify more permissive enzymes. We determined that the Pyrococcus horikoshii biotin ligase utilizes an azide-bearing biotin analog and that the Saccharomyces cerevisiae biotin ligase can utilize an alkyne-functionalized biotin analog. We subsequently demonstrated that the azidefunctionalized biotin analog can be derivatized with a phosphine probe via the Staudinger ligation. We next turned to the goal of delivering quantum dots to the cytosol of living cells, which in the future may permit intracellular single-molecule imaging. We investigated viral methods of delivery, but found that our protocol caused quantum dots to be trapped in endocytic vesicles. We then validated previous reports that the pore-forming toxin streptolysin 0 be used to deliver quantum dots to the cytosol of living cells. Lipoic acid ligase, or LpIA, has been previously applied to site-specific protein labeling of peptide-tagged proteins using small molecule probes including lipoic acid and coumarin fluorophores. We utilized LpIA and its substrate, the LAP peptide, to create sensors for proteinprotein interactions. If LpIA is fused to one protein and LAP is fused to another, only when the two proteins interact do LpIA and LAP come into proximity, allowing probe ligation onto the peptide to occur as a readout of the interaction. We demonstrate that proximity-dependent coumarin ligation detects protein-protein interactions in living mammalian cells with extremely low background, a signal-to-background ratio of at least 5:1, and sufficiently fast kinetics to label interactions with a half-life of at least 1 minute. The reporter quantitatively responds to subpopulations of interacting proteins, allowing dissociation constants to be measured. Coumarin fluorescence accurately reports the subcellular localization of the interaction under study. Finally, we applied proximity-dependent coumarin ligation to imaging of the interaction of PSD-95 and neuroligin-1, two proteins involved in synaptic maturation, in neurons.
Rational Design and Directed Evolution of Probe Ligases for Site-specific Protein Labeling and Live-cell Imaging
Rational Design and Directed Evolution of Probe Ligases for Site-specific Protein Labeling and Live-cell Imaging - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Rational Design and Directed Evolution of Probe Ligases for Site-specific Protein Labeling and Live-cell Imaging write by Katharine Alice White. This book was released on 2012. Rational Design and Directed Evolution of Probe Ligases for Site-specific Protein Labeling and Live-cell Imaging available in PDF, EPUB and Kindle. Chemical fluorophores have superior photophysical properties to fluorescent proteins and are much smaller. However, in order to use these probes for live-cell protein imaging, highly specific labeling methods are required. Here, we will describe three efforts to re-engineer the E. coli enzyme, lipoic acid ligase (LplA), to catalyze the ligation of small-molecule probes onto recombinant proteins. We call this collection of methods the PRIME (PRobe Incorporation Mediated by Enzymes) methodologies. First, we describe the structure-guided mutagenesis of LplA and the identification of an LplA variant that can ligate a blue coumarin fluorophore onto a 13-amino acid LplA acceptor peptide (LAP2). This "coumarin ligase" can be used to image cellular proteins with high specificity, sensitivity, and minimal perturbation of the biology of the protein of interest. We also demonstrate how subpopulations of a protein of interest can be labeled using genetically targeted coumarin ligase. Second, we describe our attempts to use yeast display evolution and fluorescence activated cell sorting (FACS) to evolve a truncated LplA enzyme. The original truncated enzyme had severely decreased activity for LplA's natural substrate, lipoic acid. We created a 107 library of LplA mutants and, after four rounds of selection, produced a truncated LplA mutant with lipoylation activity equivalent to full-length LplA. We next sought to evolve activity for an unnatural small molecule probe, but found that this strategy was limited by both increased hydrophobic probe sticking when using the truncated enzyme and some enzyme-dependent nonspecificity. Finally, from a library of 107 LplA mutants, we evolved a full-length LplA capable of ligating an unnatural picolyl azide (pAz) substrate. We demonstrated improved activity of the "pAz ligase" in the secretory pathway and cell surface, two regions where coumarin ligase is inactive. This enzyme can also be used to image cell surface protein-protein interactions as well as label proteins as they are trafficked through the endoplasmic reticulum. These probe ligases will be useful tools for cell biologists interested in studying protein function or protein-protein interactions in the context of living cells.
RNA-protein Interactions
RNA-protein Interactions - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook RNA-protein Interactions write by Kiyoshi Nagai. This book was released on 1994. RNA-protein Interactions available in PDF, EPUB and Kindle. The study of RNA-protein interactions is crucial to understanding the mechanisms and control of gene expression and protein synthesis. The realization that RNAs are often far more biologically active than was previously appreciated has stimulated a great deal of new research in this field. Uniquely, in this book, the world's leading researchers have collaborated to produce a comprehensive and current review of RNA-protein interactions for all scientists working in this area. Timely, comprehensive, and authoritative, this new Frontiers title will be invaluable for all researchers in molecular biology, biochemistry and structural biology.
Bioconjugate Techniques
Bioconjugate Techniques - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Bioconjugate Techniques write by Greg T. Hermanson. This book was released on 2010-07-26. Bioconjugate Techniques available in PDF, EPUB and Kindle. Bioconjugate Techniques, 2nd Edition, is the essential guide to the modification and cross linking of biomolecules for use in research, diagnostics, and therapeutics. It provides highly detailed information on the chemistry, reagent systems, and practical applications for creating labeled or conjugate molecules. It also describes dozens of reactions with details on hundreds of commercially available reagents and the use of these reagents for modifying or cross linking peptides and proteins, sugars and polysaccharides, nucleic acids and oligonucleotides, lipids, and synthetic polymers. A one-stop source for proven methods and protocols for synthesizing bioconjugates in the lab Step-by-step presentation makes the book an ideal source for researchers who are less familiar with the synthesis of bioconjugates More than 600 figures that visually describe the complex reactions associated with the synthesis of bioconjugates Includes entirely new chapters on the latest areas in the field of bioconjugation as follows: Microparticles and nanoparticlesSilane coupling agentsDendrimers and dendronsChemoselective ligationQuantum dotsLanthanide chelatesCyanine dyesDiscrete PEG compoundsBuckyballs,fullerenes, and carbon nanotubesMass tags and isotope tagsBioconjugation in the study of protein interactions
Enzyme-Mediated Ligation Methods
Enzyme-Mediated Ligation Methods - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Enzyme-Mediated Ligation Methods write by Timo Nuijens. This book was released on 2019-06-03. Enzyme-Mediated Ligation Methods available in PDF, EPUB and Kindle. This volume discusses different enzyme-catalyzed ligation methodologies for a variety of different chemical transformations. This book wants readers to view enzymes as a powerful tool in both academic and industrial research. Chapters in this book cover topics such as sortase A-mediated generation of site-specifically conjugated antibody-drug conjugates; omniligase-catalyzed inter- and intramolecular ligation; ligation catalyzed by microbial transglutaminase; peptide cyclization mediated by cyanobactin macrocyclases, butelase 1 and sortase A; using BioID as a tool for protein proximity labeling in living cells; and inducible, selective labeling of proteins via enzymatic oxidation of tyrosine. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and thorough, Enzyme-Mediated Ligation Methods is a valuable resource for students and scientists from different disciplines who are interested in using enzymatic strategies to answer their research questions.
