Effects of signal sequences and folding accessory proteins on extracellular expression of carboxypeptidase Y in recombinant Saccharomyces cerevisiae

Carboxypeptidase Y (CPY) is a yeast vacuolar protease with useful applications including C-terminal sequencing of peptides and terminal modification of target proteins. To overexpress CPY with the pro-sequence (proCPY) encoded by the Saccharomyces cerevisiae PRC1 gene in recombinant S. cerevisiae, the proCPY gene was combined with the gene coding for a signal sequence of S. cerevisiae mating factor α (MFα), invertase (SUC2), or Kluyveromyces marxianus inulinase (INU1). Among the three constructs, the MFα signal sequence gave the best specific activity of extracellular CPY. To enhance the CPY expression level, folding accessory proteins of Kar2p, Pdi1p and Ero1p located in the S. cerevisiae endoplasmic reticulum were expressed individually and combinatorially. A single expression of Kar2p led to a 28 % enhancement in extracellular CPY activity, relative to the control strain of S. cerevisiae CEN.PK2-1D/p426Gal1-MFαCPY. Coexpression of Kar2p, Pdi1p and Ero1p gave a synergistic effect on CPY expression, of which activity was 1.7 times higher than that of the control strain. This work showed that engineering of signal sequences and protein-folding proteins would be helpful to overexpress yeast proteins of interest.     

Genome sequence of Corynebacterium nuruki S6-4 T, isolated from alcohol fermentation starter

Corynebacterium nuruki S6-4(T), isolated from Korean alcohol fermentation starter, is a strictly aerobic, nonmotile, Gram-positive, and rod-shaped bacterium belonging to the genus Corynebacterium and the actinomycete group. We report here the draft genome sequence of C. nuruki strain S6-4(T) (3,106,595 bp, with a G+C content of 69.5%).     

In vivo specific delivery of c-Met siRNA to glioblastoma using cationic solid lipid nanoparticles

RNA interference is a powerful strategy that inhibits gene expression through specific mRNA degradation. In vivo, however, the application of small interfering RNAs (siRNAs) is severely limited by their instability and their poor delivery into target cells and tissues. This is especially true with glioblastomas (GBMs), the most frequent and malignant form of brain tumor, that has limited treatment options due to the largely impenetrable blood-brain barrier. Here, cationic solid lipid nanoparticles (SLN), reconstituted from natural components of protein-free low-density lipoprotein, was conjugated to PEGylated c-Met siRNA. The c-Met siRNA-PEG/SLN complex efficiently down-regulated c-Met expression level, as well as decreased cell proliferation in U-87MG in vitro. In orthotopic U-87MG xenograft tumor model, intravenous administration of the complex significantly inhibited c-Met expression at the tumor tissue and suppressed tumor growth without showing any systemic toxicity in mice. Use of Cy5.5 conjugated SLN revealed enhanced accumulation of the siRNA-PEG/SLN complexes specifically in the brain tumor. Our data demonstrates the feasibility of using siRNA-PEG/SLN complexes as a potential carrier of therapeutic siRNAs for the systemic treatment of GBM in the clinic.     

Acupuncture enhances the synaptic dopamine availability to improve motor function in a mouse model of Parkinson's disease

Parkinson's disease (PD) is caused by the selective loss of dopaminergic neurons in the substantia nigra (SN) and the depletion of striatal dopamine (DA). Acupuncture, as an alternative therapy for PD, has beneficial effects in both PD patients and PD animal models, although the underlying mechanisms therein remain uncertain. The present study investigated whether acupuncture treatment affected dopamine neurotransmission in a PD mouse model using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We found that acupuncture treatment at acupoint GB34 improved motor function with accompanying dopaminergic neuron protection against MPTP but did not restore striatal dopamine depletion. Instead, acupuncture treatment increased dopamine release that in turn, may lead to the enhancement of dopamine availability in the synaptic cleft. Moreover, acupuncture treatment mitigated MPTP-induced abnormal postsynaptic changes, suggesting that acupuncture treatment may increase postsynaptic dopamine neurotransmission and facilitate the normalization of basal ganglia activity. These results suggest that the acupuncture-induced enhancement of synaptic dopamine availability may play a critical role in motor function improvement against MPTP.     

Cloning,expression, and PCR application of DNA polymerase from the hyperthermophilic archaeon, <Emphasis Type="Italic">Thermococcus celer</Emphasis>

The family B DNA polymerase gene was amplified from Thermococcus celer genomic DNA by using the degenerate primers and DNA walking PCR. The Tce DNA polymerase gene was cloned and sequenced. The gene contains an ORF of 2,325 bp encoding 774 amino acid residues with a calculated molecular weight of 89,788.9 kDa. The Tce DNA polymerase was purified by heat treatment and heparin column chromatography. The optimal conditions for PCR were determined. Long-range PCR and time-saving PCR were performed using various specific ratios of Taq and Tce DNA polymerases (Tce plus DNA polymerase). Tce plus DNA polymerase surpassed the PCR performance of Tce, Taq and Pfu DNA polymerases in terms of yield and efficiency.