A Non-hydrolyzable ATP Derivative Generates a Stable Complex in a Light-inducible Two-component System

Isothermal calorimetry (ITC) measurements yielded the binding constants during complex formation of light-inducible histidine kinases (HK) and their cognate CheY-type response regulators (RR). HK-RR interactions represent the core function of the bacterial two-component system, which is also present in many bacterial phytochromes. Here, we have studied the recombinant forms of phytochromes CphA and CphB from the cyanobacterium Tolypothrix PCC7601 and their cognate RRs RcpA and RcpB. The interaction between the two reaction partners (HK and RR) was studied in the presence and absence of ATP. A complex formation was observable in the presence of ATP, but specific interactions were only found when a non-hydrolyzable ATP derivative was added to the mixture. Also, the incubation of the HK domain alone (expressed as a recombinant protein) with the RR did not yield specific interactions, indicating that the HK domain is only active as a component of the full-length phytochrome. Considering also previous studies on the same proteins (Hübschmann, T., Jorissen, H. J. M. M., Börner, T., Gärtner, W., and de Marsac, N. (2001) Eur. J. Biochem. 268, 3383–3389) we now conclude that the HK domains of these phytochromes are active only when the chromophore domain is in its Pr form. The formerly documented phosphate transfer between the HK domain and the RR takes place via a transiently formed protein-protein complex, which becomes detectable by ITC in the presence of a non-hydrolyzable ATP derivative. This finding is of interest also in relation to the function of some (blue light-sensitive) photoreceptors that carry the HK domain and the RR fused together in one single protein.     

Orexinergic Neurotransmission in Temperature Responses to Methamphetamine and Stress: Mathematical Modeling as a Data Assimilation Approach

Experimental Data

Orexinergic neurotransmission is involved in mediating temperature responses to methamphetamine (Meth). In experiments in rats, SB-334867 (SB), an antagonist of orexin receptors (OX1R), at a dose of 10 mg/kg decreases late temperature responses (t>60 min) to an intermediate dose of Meth (5 mg/kg). A higher dose of SB (30 mg/kg) attenuates temperature responses to low dose (1 mg/kg) of Meth and to stress. In contrast, it significantly exaggerates early responses (t<60 min) to intermediate and high doses (5 and 10 mg/kg) of Meth. As pretreatment with SB also inhibits temperature response to the stress of injection, traditional statistical analysis of temperature responses is difficult.

Mathematical Modeling

We have developed a mathematical model that explains the complexity of temperature responses to Meth as the interplay between excitatory and inhibitory nodes. We have extended the developed model to include the stress of manipulations and the effects of SB. Stress is synergistic with Meth on the action on excitatory node. Orexin receptors mediate an activation of on both excitatory and inhibitory nodes by low doses of Meth, but not on the node activated by high doses (HD). Exaggeration of early responses to high doses of Meth involves disinhibition: low dose of SB decreases tonic inhibition of HD and lowers the activation threshold, while the higher dose suppresses the inhibitory component. Using a modeling approach to data assimilation appears efficient in separating individual components of complex response with statistical analysis unachievable by traditional data processing methods.     

Distal NF-kB binding motif functions as an enhancer for nontypeable H. influenzae-induced DEFB4 regulation in epithelial cells

Among the antimicrobial molecules produced by epithelial cells, DEFB4 is inducible in response to proinflammatory signals such as cytokines and bacterial molecules. Nontypeable Haemophilus influenzae (NTHi) is an important human pathogen that exacerbates chronic obstructive pulmonary disease in adult and causes otitis media and sinusitis in children. Previously, we have demonstrated that DEFB4 effectively kills NTHi and is induced by NTHi via TLR2 signaling. The 5′-flanking region of DEFB4 contains several NF-κB binding motifs, but their NTHi-specific activity remains unclear. In this study, we aimed to elucidate molecular mechanism involved in DEFB4 regulation, focusing on the role of the distal NF-κB binding motif of DEFB4 responding to NTHi. Here, we show that the human middle ear epithelial cells up-regulate DEFB4 expression in response to NTHi via NF-κB activation mediated by IκKα/β−IκBα signaling. Deletion of the distal NF-κB binding motif led to a significant reduction in NTHi-induced DEFB4 up-regulation. A heterologous construct containing the distal NF-κB binding motif was found to increase the promoter activity in response to NTHi, indicating a NTHi-responding enhancer activity of the distal NF-κB binding motif. Furthermore, electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that the p65 domain of NF-κB binds to the distal NF-κB binding motif in response to NTHi. Taken together, our results suggest that NTHi-induced binding of p65 NF-κB to the distal NF-κB binding motif of DEFB4 enhances NTHi-induced DEFB4 regulation in epithelial cells.     

Anticancer activity of TTAC-0001, a fully human anti-vascular endothelial growth factor receptor 2 (VEGFR-2/KDR) monoclonal antibody,is associated with inhibition of tumor angiogenesis

Vascular endothelial growth factor (VEGF) and its receptors are considered the primary cause of tumor-induced angiogenesis. Specifically, VEGFR-2/kinase insert domain receptor (KDR) is part of the major signaling pathway that plays a significant role in tumor angiogenesis, which is associated with the development of various types of tumor and metastasis. In particular, KDR is involved in tumor angiogenesis as well as cancer cell growth and survival. In this study, we evaluated the therapeutic potential of TTAC-0001, a fully human antibody against VEGFR-2/KDR. To assess the efficacy of the antibody and pharmacokinetic (PK) relationship in vivo, we tested the potency of TTAC-0001 in glioblastoma and colorectal cancer xenograft models. Antitumor activity of TTAC-0001 in preclinical models correlated with tumor growth arrest, induction of tumor cell apoptosis, and inhibition of angiogenesis. We also evaluated the combination effect of TTAC-0001 with a chemotherapeutic agent in xenograft models. We were able to determine the relationship between PK and the efficacy of TTAC-0001 through in vivo single-dose PK study. Taken together, our data suggest that targeting VEGFR-2 with TTAC-0001 could be a promising approach for cancer treatment.     

An extremely alkaline mannanase from <Emphasis Type="Italic">Streptomyces</Emphasis> sp. CS428 hydrolyzes galactomannan producing series of mannooligosaccharides

An alkaline-thermostable mannanase from Streptomyces sp. CS428 was produced, purified, and biochemically characterized. The extracellular mannanase (Mn428) was purified to homogeneity with 12.4 fold, specific activity of 2406.7 U/mg, and final recovery of 37.6 %. The purified β-mannanase was found to be a monomeric protein with a molecular mass of approximately 35 kDa as analyzed by SDS-PAGE and zymography. The first N-terminal amino acid sequences of mannanase enzyme were HIRNGNHQLPTG. The optimal temperature and pH for enzyme were 60 °C and 12.5, respectively. The mannanase activities were significantly affected by the presence of metal ions, modulators, and detergents. K_m and V_max values of Mn428 were 1.01 ± 3.4 mg/mL and 5029 ± 85 µmol/min mg, respectively when different concentrations (0.6–10 mg/mL) of locust bean gum galactomannan were used as substrate. The substrate specificity of enzyme showed its highest specificity towards galactomannan which was further hydrolyzed to produce mannose, mannobiose, mannotriose, and a series of mannooligosaccharides. Mannooligosaccharides can be further converted to ethanol production, thus the purified β-mannanase isolated from Streptomyces sp. CS428 was found to be attractive for biotechnological applications.     

Synthesis and biological evaluation of 3-substituted-benzofuran-2-carboxylic esters as a novel class of ischemic cell death inhibitors

A series of 3-substituted-benzofuran-2-carboxylic esters was synthesized and evaluated for biological activity as ischemic cell death inhibitors in H9c2 cells and rat primary cardiac myocytes under conditions of oxygen and glucose deprivation. The introduction of a sulfur atom at the three-position substituent of the benzofuran ring markedly improved ischemic cell death inhibitory potency. In particular, 3-[2-(4-nitro-phenylsulfanyl)-acetylamino]-benzofuran-2-carboxylic acid ester (10) (EC(50)=0.532 μM, cell death=6.18%) and 4-chloro-3-[3-(pyridin-2-ylsulfanyl)-propionylamino]-benzofuran-2-carboxylic ester (18) (EC(50)=0.557 μM, cell death=7.02%) were shown to be the most potent in this series of benzofuran analogs.     

Development of an amphiphilic matrix for immobilization of <Emphasis Type="Italic">Candida antartica</Emphasis> lipase B for biodiesel production

Biodiesel has been greatly interested as an alternative fuel and is produced by a transesterification reaction of oil with alcohol. Recently, microbial lipases have been used for biodiesel production. Among the microbial lipase, immobilized Candida antartica lipase B (CALB) is the most widely used. However, CALB is unstable and shows low catalytic efficiency in the reaction media because the reaction media contains a high concentration of methanol and the lipase is also inhibited by the by-product glycerol. In this study, to overcome these limitations, we developed an amphiphilic matrix to immobilize CALB. The immobilized lipase in an amphiphilic matrix with 80% ethyltrimethoxysilane (ETMS) in tetramethoxysilane (TMOS) and pretreated with oil showed the highest specific activity and biodiesel conversion ratio; about 90% biodiesel conversion in 24 h at an initial molar ratio of 1: 1 (oil: methanol) with stepwise methanol feeding in order to adjust the net molar ratio to be 1: 3.     

Differences in N-glycan structures foundon recombinant IgA1 and IgA2 producedin murine myeloma and CHO cell lines

The development and production of recombinant monoclonal antibodies is well established. Although most of these are IgGs, there is also great interest in producing recombinant IgAs since this isotype plays a critical role in providing immunologic protection at mucosal surfaces. the choice of expression system for production of recombinant antibodies is crucial because they are glycoproteins containing at least one N-linked carbohydrate. these glycans have been shown to contribute to the stability, pharmacokinetics and biologic function of antibodies. We have produced recombinant human IgA1 and all three allotypes of IgA2 in murine myeloma and CHo cell lines to systematically characterize and compare the N-linked glycans. Recombinant IgAs produced in murine myelomas differ significantly from IgA found in humans in that they contain the highly immunogenic Galα(1,3)Gal epitope and N-glycolylneuraminic acid residues, indicating that murine myeloma is not the optimal expression system for the production of human IgA. In contrast, IgAs produced in CHo cells contained glycans that were more similar to those found on human IgA. expression of IgA1 and IgA2 in Lec2 and Lec8 cell lines that are defective in glycan processing resulted in a less complex pool of N-glycans. In addition, the level of sialylation of rIgAs produced in murine and CHo cells was significantly lower than that previously reported for serum IgA1. these data underscore the importance of choosing the appropriate cell line for the production of glycoproteins with therapeutic potential.Key words: recombinant antibody, IgA, glycosylation, expression system, mass spectrometry