17 research outputs found
Impaired protein translation in Drosophila models for Charcot–Marie–Tooth neuropathy caused by mutant tRNA synthetases
Dominant mutations in five tRNA synthetases cause Charcot–Marie–Tooth (CMT) neuropathy, suggesting that altered aminoacylation function underlies the disease. However, previous studies showed that loss of aminoacylation activity is not required to cause CMT. Here we present a Drosophila model for CMT with mutations in glycyl-tRNA synthetase (GARS). Expression of three CMT-mutant GARS proteins induces defects in motor performance and motor and sensory neuron morphology, and shortens lifespan. Mutant GARS proteins display normal subcellular localization but markedly reduce global protein synthesis in motor and sensory neurons, or when ubiquitously expressed in adults, as revealed by FUNCAT and BONCAT. Translational slowdown is not attributable to altered tRNA[superscript Gly] aminoacylation, and cannot be rescued by Drosophila Gars overexpression, indicating a gain-of-toxic-function mechanism. Expression of CMT-mutant tyrosyl-tRNA synthetase also impairs translation, suggesting a common pathogenic mechanism. Finally, genetic reduction of translation is sufficient to induce CMT-like phenotypes, indicating a causal contribution of translational slowdown to CMT.National Institutes of Health (U.S.) (Grant GM17151
Expression of IMP1 Enhances Production of Murine Leukemia Virus Vector by Facilitating Viral Genomic RNA Packaging
Murine leukemia virus (MLV)-based retroviral vector is widely used for gene transfer. Efficient packaging of the genomic RNA is critical for production of high-titer virus. Here, we report that expression of the insulin-like growth factor II mRNA binding protein 1 (IMP1) enhanced the production of infectious MLV vector. Overexpression of IMP1 increased the stability of viral genomic RNA in virus producer cells and packaging of the RNA into progeny virus in a dose-dependent manner. Downregulation of IMP1 in virus producer cells resulted in reduced production of the retroviral vector. These results indicate that IMP1 plays a role in regulating the packaging of MLV genomic RNA and can be used for improving production of retroviral vectors
Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau
The potential role of Alu Y in the development of resistance to SN38 (Irinotecan) or oxaliplatin in colorectal cancer
Effects of cobalt precursor on pyrolyzed carbon-supported cobalt-polypyrrole as electrocatalyst toward oxygen reduction reaction
The Zinc Finger Antiviral Protein Directly Binds to Specific Viral mRNAs through the CCCH Zinc Finger Motifs
The zinc finger antiviral protein (ZAP) is a recently isolated host antiviral factor. It specifically inhibits the replication of Moloney murine leukemia virus (MLV) and Sindbis virus (SIN) by preventing the accumulation of viral RNA in the cytoplasm. For this report, we mapped the viral sequences that are sensitive to ZAP inhibition. The viral sequences were cloned into a luciferase reporter and analyzed for the ability to mediate ZAP-dependent destabilization of the reporter. The sensitive sequence in MLV was mapped to the 3′ long terminal repeat; the sensitive sequences in SIN were mapped to multiple fragments. The fragment of SIN that displayed the highest destabilizing activity was further analyzed by deletion mutagenesis for the minimal sequence that retained the activity. This led to the identification of a fragment of 653 nucleotides. Any further deletion of this fragment resulted in significantly lower activity. We provide evidence that ZAP directly binds to the active but not the inactive fragments. The CCCH zinc finger motifs of ZAP play important roles in RNA binding and antiviral activity. Disruption of the second and fourth zinc fingers abolished ZAP's activity, whereas disruption of the first and third fingers just slightly lowered its activity
Nanozymatic Activity of UiO-66 Metal-Organic Frameworks: Tuning the Nanopore Environment Enhances Hydrolytic Activity toward Peptide Bonds
status: publishe
Superactivity of MOF-808 toward Peptide Bond Hydrolysis
MOF-808,
a ZrÂ(IV)-based metal–organic framework, has been
proven to be a very effective heterogeneous catalyst for the hydrolysis
of the peptide bond in a wide range of peptides and in hen egg white
lysozyme protein. The kinetic experiments with a series of Gly-X dipeptides
with varying nature of amino acid side chain have shown that MOF-808
exhibits selectivity depending on the size and chemical nature of
the X side chain. Dipeptides with smaller or hydrophilic residues
were hydrolyzed faster than those with bulky and hydrophobic residues
that lack electron rich functionalities which could engage in favorable
intermolecular interactions with the btc linkers. Detailed kinetic
studies performed by <sup>1</sup>H NMR spectroscopy revealed that
the rate of glycylglycine (Gly-Gly) hydrolysis at pD 7.4 and 60 °C
was 2.69 × 10<sup>–4</sup> s<sup>–1</sup> (<i>t</i><sub>1/2</sub> = 0.72 h), which is more than 4 orders of
magnitude faster compared to the uncatalyzed reaction. Importantly,
MOF-808 can be recycled several times without significantly compromising
the catalytic activity. A detailed quantum-chemical study combined
with experimental data allowed to unravel the role of the {Zr<sub>6</sub>O<sub>8</sub>} core of MOF-808 in accelerating Gly-Gly hydrolysis.
A mechanism for the hydrolysis of Gly-Gly by MOF-808 is proposed in
which Gly-Gly binds to two ZrÂ(IV) centers of the {Zr<sub>6</sub>O<sub>8</sub>} core via the oxygen atom of the amide group and the N-terminus.
The activity of MOF-808 was also demonstrated toward the hydrolysis
of hen egg white lysozyme, a protein consisting of 129 amino acids.
Selective fragmentation of the protein was observed with 55% yield
after 25 h under physiological pH