Molecular cloning and expression analysis of phospholipase Cdelta from mud loach, Misgurnus mizolepis

A gene encoding phosphoinositide-specific phospholipase C (PLC), designated ML-PLCδ, was cloned from mud loach (Misgurnus mizolepis) liver. A complete cDNA encoding ML-PLCδ was isolated by screening the cDNA library of mud loach liver and using the 5′-rapid amplification of cDNA ends (RACE) method. The full-length ML-PLCδ gene contains an open reading frame of 2325 base pairs encoding a 774 amino acid protein with a molecular mass of 88,072 Da; this corresponds to the size of the protein expressed in Escherichia coli BL21 (DE3) using pET28a vector. It contains all of the characteristic domains found in mammalian PLCδ isozymes (PH domain, EF-hands, X–Y catalytic region, and a C2 domain). A homology search revealed that ML-PLCδ shares relatively high sequence identity with mammalian PLCδ1 (51–52%) and catfish PLCδ (64%). The recombinant ML-PLCδ protein expressed as a histidine-tagged fusion protein in E. coli was purified to apparent homogeneity by Ni²⁺-NTA affinity chromatography. The recombinant ML-PLCδ showed a concentration-dependent PLC activity to phosphatidylinositol 4,5-bis-phosphate (PIP₂) and its activity was Ca²⁺-dependent, which was similar to mammalian PLCδ isozymes.     

Enantioselective synthesis of (S)-3-carboxy-4-((carboxy)difluoromethyl)phenylalanine in protected form and its incorporation into a PTP-1B-directed tripeptide

Recent findings have shown that, when expressed in the tripeptide platform, 'Fmoc-Glu-Xxx-Leu-amide', the phosphotyrosyl mimetic (pTyr), Xxx=(S)-3-carboxy-4-(carboxymethyl)-Phe, provides higher PTP-1B affinity than that obtained with Xxx=(S)-difluorophosphonomethyl-Phe (F(2)Pmp). This was of note, since difluorophosphonomethyl-containing pTyr mimetics have typically exhibited higher PTP-inhibitory potencies than carboxy-based mimetics, indicating the potential value of 3-carboxy-4-(carboxymethyl)-Phe as a starting point for further analogue development. Therefore, relying on precedence that alpha-fluorination often enhances PTP-1B affinity, (S)-3-carboxy-4-((carboxy)difluoromethyl)-Phe was designed as a PTP-1B-directed pTyr mimetic. Reported herein is the synthesis of this new amino acid analogue through application of commercially available Williams chiral auxiliary. The target was prepared in an orthogonally protected form suitable for peptide synthesis according to Fmoc chemistries and utilization for the synthesis of a PTP-1B-directed tripeptide bearing the sequence indicated above. Biological evaluation with in vitro PTP-1B assays indicated nearly total loss of affinity for this peptide. Evidence is provided that the unexpected deleterious effect of fluorination is probably not related to pK(a) effects.     

Molecular characterization of gene encoding an extracellular alkaline protease in Vibrio metschnikovii

The gene, vapK, encoding an extracellular alkaline protease, VapK, in Vibrio metschnikovii strain RH530 was cloned and expressed in Escherichia coli. The nucleotide sequence of the vapK revealed a single open reading frame of 1266 bp encoding 422 amino acids. The biochemical characteristics of the expressed protease were indistinguishable from those of VapK from the wild type strain. The recombinant VapK showed resistant activity to surfactants such as sodium -olefin sulfonate, polyoxyethylene oxide, SDS and urea. The surfactant, sodium alkylbenzenesulfonate, strongly inhibited the activity of re-VapK. However in the presence of POE or Na₂SO₄, its activity was completely restored. By N-terminal sequencing of VapK, the cleavage site for the mature protease could be identified. The cleavage site was Ala¹⁴⁰ and the calculated molecular mass of the mature enzyme was 29 609 Da, corresponding to the purified VapK. The active sites and putative calcium binding sites of recombinant VapK (re-VapK) were highly conserved when compared to subtilisin Carlsberg.     

Regulation of Autoimmune Germinal Center Reactions in Lupus-Prone BXD2 Mice by Follicular Helper T Cells

BXD2 mice spontaneously develop autoantibodies and subsequent glomerulonephritis, offering a useful animal model to study autoimmune lupus. Although initial studies showed a critical contribution of IL-17 and Th17 cells in mediating autoimmune B cell responses in BXD2 mice, the role of follicular helper T (Tfh) cells remains incompletely understood. We found that both the frequency of Th17 cells and the levels of IL-17 in circulation in BXD2 mice were comparable to those of wild-type. By contrast, the frequency of PD-1⁺CXCR5⁺ Tfh cells was significantly increased in BXD2 mice compared with wild-type mice, while the frequency of PD-1⁺CXCR5⁺Foxp3⁺ follicular regulatory T (Tfr) cells was reduced in the former group. The frequency of Tfh cells rather than that of Th17 cells was positively correlated with the frequency of germinal center B cells as well as the levels of autoantibodies to dsDNA. More importantly, CXCR5⁺ CD4⁺ T cells isolated from BXD2 mice induced the production of IgG from naïve B cells in an IL-21-dependent manner, while CCR6⁺ CD4⁺ T cells failed to do so. These results together demonstrate that Tfh cells rather than Th17 cells contribute to the autoimmune germinal center reactions in BXD2 mice.     

Chronic Obstructive Pulmonary Disease-Related Non-Small-Cell Lung Cancer Exhibits a Low Prevalence of EGFR and ALK Driver Mutations

Lung cancer and chronic obstructive pulmonary disease (COPD) are two major lung diseases. Epidermal growth factor receptor (EGFR) mutations, v‐Ki‐ras2 Kirsten rat sarcoma (KRAS) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements represent driver mutations that are frequently assessed on initial evaluation of non-small-cell lung cancer (NSCLC). The present study focused on the expression of driver mutations in NSCLC patients presenting with COPD and further evaluated the association between NSCLC and COPD. Data from 501 consecutive patients with histologically proven recurrent or metastatic NSCLC were analyzed retrospectively. The patients underwent spirometry and genotyping of EGFR, ALK, and KRAS in tissue samples. Patient characteristics and expression of driver mutations were compared between the COPD and non-COPD groups.Among 350 patients with spirometric results, 106 (30.3%) were diagnosed with COPD, 108 (30.9%) had EGFR mutations, 31 (8.9%) had KRAS mutations, and 34 (9.7%) showed ALK rearrangements. COPD was independently associated with lower prevalences of EGFR mutations (95% confidence interval [CI], 0.254–0.931, p = 0.029) and ALK rearrangements (95% CI, 0.065–0.600, p = 0.004). The proportions of EGFR mutations and ALK rearrangements decreased as the severity of airflow obstruction increased (p = 0.001). In never smokers, the prevalence of EGFR mutations was significantly lower in the COPD group than in the non-COPD group (12.7% vs. 49.0%, p = 0.002). COPD-related NSCLC patients exhibited low prevalences of EGFR mutations and ALK rearrangements compared with the non-COPD group. Further studies are required regarding the molecular mechanisms underlying lung cancer associated with COPD.     

Extremely High Yield Conversion from Low‐Cost Sand to High‐Capacity Si Electrodes for Li‐Ion Batteries

Although magnesiothermic reduction has attracted immense attention as a facile route for the fabrication of mass‐scale Si nanostructures for high‐capacity lithium‐ion battery applications, its low conversion yield (<50%) and the discovery of a sustainable and low‐cost precursor remain challenging. Here, an unprecedentedly high final conversion yield (>98%) of magnesiothermic reduction based on control of reaction pressure is reported. The successful use of sand as a nearly infinite and extremely low‐cost source for the high‐yield fabrication of nanostructured Si electrodes for Li‐ion batteries is demonstrated. On the basis of a step‐by‐step analysis of the material's structural, morphological, and compositional changes, a two‐step conversion reaction mechanism is proposed that can clearly explain the phase behavior and the high conversion yield. The excellent charge–discharge performance (specific capacities over 1500 mAh g^‐1 for 100 cycles) of the hierarchical Si nanostructure suggests that this facile, fast, and high‐efficiency synthesis strategy from ultralow‐cost sand particles provides outstanding cost‐effectiveness and possible scalability for the commercialization of Si electrodes for energy‐storage applications.     

Isolation and functional characterization of a delta 6-desaturase gene from the pike eel (Muraenesox cinereus)

Stearidonic acid (STA; 18:4n-3) and γ-linolenic acid (GLA; 18:3n-6) are significant intermediates in the biosynthetic pathway for the very-long-chain polyunsaturated fatty acids of eicosapentaenoic acid (EPA; 20:5n-3) and arachidonic acid (ARA; 20:4n-6), respectively. To develop a sustainable system for the production of dietary polyunsaturated fatty acids, we focused on the action of the enzyme delta 6-desaturase (D6DES) on the essential acids, linoleic acid (LA; 18:2n-6) and α-linolenic acid (ALA; 18:3n-3). A 1,335-bp full-length cDNA encoding D6DES (McD6DES) was cloned from Muraenesox cinereus using degenerate PCR and RACE-PCR methods. To investigate the enzymatic activity of McD6DES in the production of n-6 and n-3 fatty acids, a recombinant plasmid expressing McD6DES (pYES-McD6DES) was transformed into and expressed in Saccharomyces cerevisiae. The exogenously expressed McD6DES produced GLA and STA at conversion rates of 14.2% and 45.9%, respectively, from the exogenous LA and ALA substrates. These results indicate that McD6DES is essentially a delta 6-desaturase involved in very-long-chain polyunsaturated fatty acid synthesis.     

Malonyl-CoA synthetase, encoded by ACYL ACTIVATING ENZYME13, is essential for growth and development of Arabidopsis

Malonyl-CoA is the precursor for fatty acid synthesis and elongation. It is also one of the building blocks for the biosynthesis of some phytoalexins, flavonoids, and many malonylated compounds. In plants as well as in animals, malonyl-CoA is almost exclusively derived from acetyl-CoA by acetyl-CoA carboxylase (EC 6.4.1.2). However, previous studies have suggested that malonyl-CoA may also be made directly from malonic acid by malonyl-CoA synthetase (EC 6.2.1.14). Here, we report the cloning of a eukaryotic malonyl-CoA synthetase gene, Acyl Activating Enzyme13 (AAE13; At3g16170), from Arabidopsis thaliana. Recombinant AAE13 protein showed high activity against malonic acid (K(m) = 529.4 ± 98.5 μM; V(m) = 24.0 ± 2.7 μmol/mg/min) but little or no activity against other dicarboxylic or fatty acids tested. Exogenous malonic acid was toxic to Arabidopsis seedlings and caused accumulation of malonic and succinic acids in the seedlings. aae13 null mutants also grew poorly and accumulated malonic and succinic acids. These defects were complemented by an AAE13 transgene or by a bacterial malonyl-CoA synthetase gene under control of the AAE13 promoter. Our results demonstrate that the malonyl-CoA synthetase encoded by AAE13 is essential for healthy growth and development, probably because it is required for the detoxification of malonate.