BERNARDSVILLE, NJ, United States
BERNARDSVILLE, NJ, United States

Time filter

Source Type

Patent
University of Pennsylvania and Anima Cell Metrology, Inc | Date: 2017-02-09

Provided are methods for labeling transfer RNA comprising replacing the uracil component of a dihydrouridine of said transfer RNA with a fluorophore. The disclosed methods may comprise fluorescent labeling of natural tRNAs (i.e., tRNAs that have been synthesized in a cell, for example, in a bacterium, a yeast cell, or a vertebrate cell) at dihydrouridine (D) positions, or fluorescent labeling of synthetic tRNAs. In another aspect, the present invention provides methods for assessing protein synthesis in a translation system comprise providing a tRNA having a fluorophore substitution for the uracil component of a dihydrouridine in a D loop of the tRNA; introducing the labeled tRNA into the translation system; irradiating the translation system with electromagnetic radiation, thereby generating a fluorescence signal from the fluorophore; detecting the fluorescence signal; and, correlating the fluorescence signal to one or more characteristics of the protein synthesis in the translation system. The disclosed methods are useful in single molecule as well as in ensemble settings.


Rosenblum G.,University of Pennsylvania | Chen C.,University of Pennsylvania | Kaur J.,Anima Cell Metrology, Inc | Cui X.,University of Pennsylvania | And 2 more authors.
Nucleic Acids Research | Year: 2012

We present a flexible, real-time-coupled transcription-translation assay that involves the continuous monitoring of fluorescent Emerald GFP formation. Along with numerical simulation of a reaction kinetics model, the assay permits quantitative estimation of the effects on full-length protein synthesis of various additions, subtractions or substitutions to the protein synthesis machinery. Since the assay uses continuous fluorescence monitoring, it is much simpler and more rapid than other assays of protein synthesis and is compatible with high-throughput formats. Straightforward alterations of the assay permit determination of (i) the fraction of ribosomes in a cell-free protein synthesis kit that is active in full-length protein synthesis and (ii) the relative activities in supporting protein synthesis of modified (e.g. mutated, fluorescent-labeled) exogenous components (ribosomes, amino acid-specific tRNAs) that replace the corresponding endogenous components. Ribosomes containing fluorescentlabeled L11 and tRNAs labeled with fluorophores in the D-loop retain substantial activity. In the latter case, the extent of activity loss correlates with a combination of steric bulk and hydrophobicity of the fluorophore. © The Author(s) 2012. Published by Oxford University Press.


Chen C.,University of Pennsylvania | Zhang H.,University of Pennsylvania | Broitman S.L.,West Chester University | Reiche M.,University of Pennsylvania | And 4 more authors.
Nature Structural and Molecular Biology | Year: 2013

During protein synthesis, the ribosome translates nucleotide triplets in single-stranded mRNA into polypeptide sequences. Strong downstream mRNA secondary structures, which must be unfolded for translation, can slow or even halt protein synthesis. Here we used single-molecule fluorescence resonance energy transfer to determine reaction rates for specific steps within the elongation cycle as the Escherichia coli ribosome encounters stem-loop or pseudoknot mRNA secondary structures. Downstream stem-loops containing 100% GC base pairs decrease the rates of both tRNA translocation within the ribosome and deacylated tRNA dissociation from the ribosomal exit site (E site). Downstream stem-loops or pseudoknots containing both GC and AU pairs also decrease the rate of tRNA dissociation, but they have little effect on tRNA translocation rate. Thus, somewhat unexpectedly, unfolding of mRNA secondary structures is more closely coupled to E-site tRNA dissociation than to tRNA translocation. © 2013 Nature America, Inc. All rights reserved.


Chen C.,University of Pennsylvania | Zhang H.,University of Pennsylvania | Broitman S.L.,West Chester University | Reiche M.,University of Pennsylvania | And 3 more authors.
Nature Structural and Molecular Biology | Year: 2013

During protein synthesis, the ribosome translates nucleotide triplets in single-stranded mRNA into polypeptide sequences. Strong downstream mRNA secondary structures, which must be unfolded for translation, can slow or even halt protein synthesis. Here we used single-molecule fluorescence resonance energy transfer to determine reaction rates for specific steps within the elongation cycle as the Escherichia coli ribosome encounters stem-loop or pseudoknot mRNA secondary structures. Downstream stem-loops containing 100% GC base pairs decrease the rates of both tRNA translocation within the ribosome and deacylated tRNA dissociation from the ribosomal exit site (E site). Downstream stem-loops or pseudoknots containing both GC and AU pairs also decrease the rate of tRNA dissociation, but they have little effect on tRNA translocation rate. Thus, somewhat unexpectedly, unfolding of mRNA secondary structures is more closely coupled to E-site tRNA dissociation than to tRNA translocation.


Kaur J.,University of Pennsylvania | Kaur J.,Anima Cell Metrology, Inc | Raj M.,University of Pennsylvania | Raj M.,New York University | Cooperman B.S.,University of Pennsylvania
RNA | Year: 2011

Dihydrouridine (DHU) positions within tRNAs have long been used as sites to covalently attach fluorophores, by virtue of their unique chemical reactivity toward reduction by NaBH4, their abundance within prokaryotic and eukaryotic tRNAs, and the biochemical functionality of the labeled tRNAs so produced. Interpretation of experiments employing labeled tRNAs can depend on knowing the distribution of dye among the DHU positions present in a labeled tRNA. Here we combine matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS) analysis of oligonucleotide fragments and thin layer chromatography to resolve and quantify sites of DHU labeling by the fluorophores Cy3, Cy5, and proflavin in Escherichia coli tRNAPhe and E. coli tRNAArg. The MALDI-MS results led us to re-examine the precise chemistry of the reactions that result in fluorophore introduction into tRNA. We demonstrate that, in contrast to an earlier suggestion that has long been unchallenged in the literature, such introduction proceeds via a substitution reaction on tetrahydrouridine, the product of NaBH4 reduction of DHU, resulting in formation of substituted tetrahydrocytidines within tRNA. Published by Cold Spring Harbor Laboratory Press. Copyright © 2011 RNA Society.


Rosenblum G.,University of Pennsylvania | Chen C.,University of Pennsylvania | Kaur J.,Anima Cell Metrology, Inc | Cui X.,University of Pennsylvania | And 6 more authors.
Journal of the American Chemical Society | Year: 2013

Pauses regulate the rhythm of ribosomal protein synthesis. Mutations disrupting even minor pauses can give rise to improperly formed proteins and human disease. Such minor pauses are difficult to characterize by ensemble methods, but can be readily examined by single-molecule (sm) approaches. Here we use smFRET to carry out real-time monitoring of the expression of a full-length protein, the green fluorescent protein variant Emerald GFP. We demonstrate significant correlations between measured elongation rates and codon and isoacceptor tRNA usage, and provide a quantitative estimate of the effect on elongation rate of replacing a codon recognizing an abundant tRNA with a synonymous codon cognate to a rarer tRNA. Our results suggest that tRNA selection plays an important general role in modulating the rates and rhythms of protein synthesis, potentially influencing simultaneous co-translational processes such as folding and chemical modification. © 2013 American Chemical Society.


Chen C.,University of Pennsylvania | Stevens B.,University of Pennsylvania | Stevens B.,Anima Cell Metrology, Inc | Kaur J.,University of Pennsylvania | And 10 more authors.
Molecular Cell | Year: 2011

We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3- and Cy5-labeled tRNAs. Pretranslocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid complex. EF-G{dot operator}GTP binding to both hybrid and classical PRE complexes halts these fluctuations prior to catalyzing translocation to form the posttranslocation (POST) complex. EF-G dependent translocation from the classical PRE complex proceeds via transient formation of a short-lived hybrid intermediate. A-site binding of either EF-G to the PRE complex or of aminoacyl-tRNA{dot operator}EF-Tu ternary complex to the POST complex markedly suppresses ribosome conformational lability. © 2011 Elsevier Inc.


Patent
Anima Cell Metrology, Inc and Tel Aviv University | Date: 2011-07-21

There are provided methods for detection and measurement of stress in a cell, the method including introducing a labeled tRNA into the cell and detecting a change in subcellular localization of the labeled tRNA in the cell, based on the signal emitted from the labeled tRNA. There are further provided methods and systems for the generation of a stress index of a living cell. There are further provided methods and systems for detection of stress in a living cell, comprising detection of changes in subcellular localization of labeled tRNA in a cell, wherein the detection is performed in real time.


Patent
Tel Aviv University and Anima Cell Metrology, Inc | Date: 2015-08-19

There are provided methods for detection and measurement of stress in a cell, the method including introducing a labeled tRNA into the cell and detecting a change in subcellular localization of the labeled tRNA in the cell, based on the signal emitted from the labeled tRNA. There are further provided methods and systems for the generation of a stress index of a living cell. There are further provided methods and systems for detection of stress in a living cell, comprising detection of changes in subcellular localization of labeled tRNA in a cell, wherein the detection is performed in real time.


Patent
Anima Cell Metrology, Inc | Date: 2010-09-21

The present invention relates to systems and methods for measuring the rate of translation of a target protein in cells, which are based on the detection of translation of one or more predetermined codon pairs during synthesis of the target protein. The detection is provided by a FRET signal emitted from labeled tRNA molecules which are juxtaposed during synthesis of the protein.

Loading Anima Cell Metrology, Inc collaborators
Loading Anima Cell Metrology, Inc collaborators