Three-dimensional common-feature hypotheses for octopamine agonist 2-(arylimino)imidazolidines.

Three-dimensional pharmacophore hypotheses were built from a set of 10 octopamine (OA) agonist 2-(Arylimino)imidazolidines (AIIs), 2-(Arylimino)thiazolidines (AITs) and 2-(Arylimino)oxazolidines (AIOs). Among the 10 common-featured models generated by program Catalyst/HipHop, a hypothesis including a ring aromatic (RA), a positive ionizable (PI) and three hydrophobic aliphatic (HpAl) features was considered to be important in evaluating the OA-agonist activity. Active OA agonist 2,6-Et2 AII mapped well onto all the RA, PI and HpAl features of the hypothesis. On the other hand, less active compounds were shown to be difficult to achieve the energetically favorable conformation which is found in the active molecules in order to fit the 3-D common-feature pharmacophore models. Taken together, 2,6-Et2-Ph and foramidine structures are important as OA agonists. The present studies on OA agonists demonstrate that a RA, a PI and three HpAl sites located on the molecule seem to be essential for OA-agonist activity.     

Cloning, sequencing, and expression of the meso-diaminopimelate dehydrogenase gene from Bacillus sphaericus

The gene encoding the meso-diaminopimelate dehydrogenase of Bacillus sphaericus was cloned into E. coli cells and its complete DNA sequence was determined. The meso-diaminopimelate dehydrogenase gene consisted of 978 nucleotides and encoded 326 amino acid residues corresponding to the subunit of the dimeric enzyme. The amino acid sequence deduced from the nucleotide sequence of the enzyme gene of B. sphaericus showed 50% identity with those of the enzymes from Corynebacterium glutamicum and Brevibacterium flavum. The enzyme gene from B. sphaericus was highly expressed in E. coli cells. We purified the enzyme to homogeneity from a transformant with 76% recovery. The N-terminal amino acid of both the enzyme from B. sphaericus and the transformant were serine, indicating that the N-terminal methionine is removed by post-translational modification in B. sphaericus and E. coli cells.     

Legionella hijacks the host Golgi-to-ER retrograde pathway for the association of Legionella-containing vacuole with the ER

Legionella pneumophila (L. pneumophila) is a gram-negative bacterium that replicates in a compartment that resembles the host endoplasmic reticulum (ER). To create its replicative niche, L. pneumophila manipulates host membrane traffic and fusion machineries. Bacterial proteins called Legionella effectors are translocated into the host cytosol and play a crucial role in these processes. In an early stage of infection, Legionella subverts ER-derived vesicles (ERDVs) by manipulating GTPase Rab1 to facilitate remodeling of the Legionella-containing vacuole (LCV). Subsequently, the LCV associates with the ER in a mechanism that remains elusive. In this study, we show that L. pneumophila recruits GTPases Rab33B and Rab6A, which regulate vesicle trafficking from the Golgi to the ER, to the LCV to promote the association of LCV with the ER. We found that recruitment of Rab6A to the LCV depends on Rab33B. Legionella effector SidE family proteins, which phosphoribosyl-ubiquitinate Rab33B, were found to be necessary for the recruitment of Rab33B to the LCV. Immunoprecipitation experiments revealed that L. pneumophila facilitates the interaction of Rab6 with ER-resident SNAREs comprising syntaxin 18, p31, and BNIP1, but not tethering factors including NAG, RINT-1, and ZW10, which are normally required for syntaxin 18-mediated fusion of Golgi-derived vesicles with the ER. Our results identified a Rab33B-Rab6A cascade on the LCV and the interaction of Rab6 with ER-resident SNARE proteins for the association of LCV with the ER and disclosed the unidentified physiological role of SidE family proteins.     

Structure-activity relationship of clovamide and its related compounds for the inhibition of amyloid β aggregation

Alzheimer’s disease (AD), a neurodegenerative disorder, is characterized by aggregation of amyloid β-protein (Aβ). Aβ aggregates through β-sheet formation and induces cytotoxicity against neuronal cells. Inhibition of Aβ aggregation by naturally occurring compounds is thus a promising strategy for the treatment of AD. We have already reported that caffeoylquinic acids and phenylethanoid glycosides, which possess two or more catechol moieties, strongly inhibited Aβ aggregation. Clovamide (1) containing two catechol moieties, isolated from cacao beans (Theobroma cacao L.), is believed to exhibit preventive effects on Aβ aggregation. To investigate the structure-activity relationship of clovamide (1) for the inhibition of Aβ aggregation, we synthesized 1 and related compounds 2–11 through reaction between l-DOPA, d-DOPA, l-tyrosine, or l-phenylalanine and caffeic acid, p-coumaric acid, or cinnamic acid, and compounds 12 and 13 were derived from 1. Among tested compounds 1–13, those containing one or two catechol moieties exhibited potent anti-aggregation activity, whereas the non-catechol-type related compounds showed little or no activity. This suggests that at least one catechol moiety is essential for inhibition of Aβ42 aggregation, and this activity increases depending on the number of catechol moieties. Consequently, clovamide (1) and its related compounds may be a promising therapeutic option for inhibiting Aβ-mediated pathology in AD.     

Uptake of nitrogen and production of kainic acid by laboratory culture of the red alga Digenea simplex

The red alga Digenea simplex was cultured with various culture media to clarify the nutritional conditions to produce kainic acid (KA ). Unlike the domoic acid‐producing red alga Chondria armata , D. simplex was insensitive to excessive manganese, and grew best (mean growth rate approximately 800% for 25 days) in modified PES medium (mPES ; seawater + nitrate, phosphate, iron, trace metals, vitamins, and 2‐[4‐(2‐hydroxyethyl)‐1‐piperazinyl]‐ ethanesulfonic acid) prepared with autoclaved seawater. Liquid chromatography‐mass spectrometry analysis of the algal extracts revealed that the KA content of the explants cultured with mPES or N·P·Fe medium (seawater + nitrate, phosphate, and iron) was somewhat higher than that of wild specimens (1748–2378 μg g^?1 vs 1562 μg g^?1). The ¹H‐nuclear magnetic resonance spectrum of the KA extracted and purified from pooled explants was indistinguishable from the previously reported KA spectrum. When D. simplex was cultured for 6 weeks with medium in which NaNO ₃ of mPES was replaced by Na¹⁵NO ₃, the ratio of ²¹⁴KA to total measured KA (^totalKA = ²¹³KA + ²¹⁴KA ) in the cultured explants (0.1 at the beginning of culture) gradually increased to 2.5, indicating that D. simplex produces KA in proportion to its growth under the condition in which sufficient nitrogen source is available.     

Involvement of interleukin-8, vascular endothelial growth factor, and basic fibroblast growth factor in tumor necrosis factor alpha-dependent angiogenesis.

Tumor necrosis factor alpha (TNF-alpha) is a macrophage/monocyte-derived polypeptide which modulates the expression of various genes in vascular endothelial cells and induces angiogenesis. However, the underlying mechanism by which TNF-alpha mediates angiogenesis is not completely understood. In this study, we assessed whether TNF-alpha-induced angiogenesis is mediated through TNF-alpha itself or indirectly through other TNF-alpha-induced angiogenesis-promoting factors. Cellular mRNA levels of interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and their receptors were increased after the treatment of human microvascular endothelial cells with TNF-alpha (100 U/ml). TNF-alpha-dependent tubular morphogenesis in vascular endothelial cells was inhibited by the administration of anti-IL-8, anti-VEGF, and anti-bFGF antibodies, and coadministration of all three antibodies almost completely abrogated tubular formation. Moreover, treatment with Sp1, NF-kappaB, and c-Jun antisense oligonucleotides inhibited TNF-alpha-dependent tubular morphogenesis by microvascular endothelial cells. Administration of a NF-kappaB antisense oligonucleotide almost completely inhibited TNF-alpha-dependent IL-8 production and partially abrogated TNF-alpha-dependent VEGF production, and an Sp1 antisense sequence partially inhibited TNF-alpha-dependent production of VEGF. A c-Jun antisense oligonucleotide significantly inhibited TNF-alpha-dependent bFGF production but did not affect the production of IL-8 and VEGF. Administration of an anti-IL-8 or anti-VEGF antibody also blocked TNF-alpha-induced neovascularization in the rabbit cornea in vivo. Thus, angiogenesis by TNF-alpha appears to be modulated through various angiogenic factors, both in vitro and in vivo, and this pathway is controlled through paracrine and/or autocrine mechanisms.     

Three-dimensional Pharmacophore Hypotheses for the Locust Neuronal Octopamine Receptor (OAR3): 1. Antagonists

Three-dimensional pharmacophore hypotheses were built from a set of 17 mianserin-like antagonists against octopamine receptor class 3 (OAR3) in locust nervous tissue. Among the ten chemical-featured models generated by program Catalyst/Hypo, three hypotheses were considered to be important and predictive in evaluating OAR3 antagonists. Predictions were fairly precise for all molecules but the three outliners including eresepine, metoclopramide and yohimbine. While the ideal and null hypotheses had a cost of 66.50 and 124.97, respectively, the ten resulting hypotheses possessed costs from 78.96 to 92.04. The best hypothesis that was confirmed to have a 95% chance of true correlation yielded a low RMS of 1.05 and high regression r of 0.934. Active antagonists mapped well onto all the features of the hypothesis such as hydrophobic, aromatic ring or positive ionizable features. On the other hand, inactive compounds lack of binding affinity were shown to be poorly capable of achieving an energetically favorable conformation shared by the active molecules in order to fit the 3D chemical feature pharmacophore models. In addition, from the comparison and conformation analysis it was proposed that positive ionizable feature contained a lower weight than hydrophobic or an aromatic ring one. Further research on the comparison of models from agonists and antagonists may help elucidate the mechanisms of OAR3 and other types of octopamine receptor-ligand interactions.