The Aldo-Keto Reductase Superfamily and its Role in Drug Metabolism and Detoxification

The aldo-keto reductase (AKR) superfamily comprises enzymes that catalyze redox transformations involved in biosynthesis, intermediary metabolism, and detoxification. Substrates of AKRs include glucose, steroids, glycosylation end-products, lipid peroxidation products, and environmental pollutants. These proteins adopt a (β /α )₈ barrel structural motif interrupted by a number of extraneous loops and helixes that vary between proteins and bring structural identity to individual families. The human AKR family differs from the rodent families. Due to their broad substrate specificity, AKRs play an important role in the phase II detoxification of a large number of pharmaceuticals, drugs, and xenobiotics.     

Predicted hexameric structure of the Agrobacterium VirB4 C terminus suggests VirB4 acts as a docking site during type IV secretion

The Agrobacterium T-DNA transporter belongs to a growing class of evolutionarily conserved transporters, called type IV secretion systems (T4SSs). VirB4, 789 aa, is the largest T4SS component, providing a rich source of possible structural domains. Here, we use a variety of bioinformatics methods to predict that the C-terminal domain of VirB4 (including the Walker A and B nucleotide-binding motifs) is related by divergent evolution to the cytoplasmic domain of TrwB, the coupling protein required for conjugative transfer of plasmid R388 from Escherichia coli. This prediction is supported by detailed sequence and structure analyses showing conservation of functionally and structurally important residues between VirB4 and TrwB. The availability of a solved crystal structure for TrwB enables the construction of a comparative model for VirB4 and the prediction that, like TrwB, VirB4 forms a hexamer. These results lead to a model in which VirB4 acts as a docking site at the entrance of the T4SS channel and acts in concert with VirD4 and VirB11 to transport substrates (T-strand linked to VirD2 or proteins such as VirE2, VirE3, or VirF) through the T4SS.     

Nrf2/Bach1竞争调控抗氧化酶与支气管哮喘

氧化/抗氧化失衡是支气管哮喘的重要发病机制之一.抗氧化酶的基因表达均通过抗氧化反应元件(ARE)介导,核因子相关因子-2(Nrf2)能上调ARE介导抗氧化酶的基因表达,而转录因子BTBCNC异体同源体(Bach1)下调ARE介导抗氧化酶的基因表达,Nrt2/Baeh1在核内竞争调控抗氧化酶的基因表达.     

Phylogeny of the Vitamin K 2,3-Epoxide Reductase (VKOR) Family and Evolutionary Relationship to the Disulfide Bond Formation Protein B (DsbB) Family

In humans and other vertebrate animals, vitamin K 2,3-epoxide reductase (VKOR) family enzymes are the gatekeepers between nutritionally acquired K vitamins and the vitamin K cycle responsible for posttranslational modifications that confer biological activity upon vitamin K-dependent proteins with crucial roles in hemostasis, bone development and homeostasis, hormonal carbohydrate regulation and fertility. We report a phylogenetic analysis of the VKOR family that identifies five major clades. Combined phylogenetic and site-specific conservation analyses point to clade-specific similarities and differences in structure and function. We discovered a single-site determinant uniquely identifying VKOR homologs belonging to human pathogenic, obligate intracellular prokaryotes and protists. Building on previous work by Sevier et al. (Protein Science 14:1630), we analyzed structural data from both VKOR and prokaryotic disulfide bond formation protein B (DsbB) families and hypothesize an ancient evolutionary relationship between the two families where one family arose from the other through a gene duplication/deletion event. This has resulted in circular permutation of primary sequence threading through the four-helical bundle protein folds of both families. This is the first report of circular permutation relating distant α-helical membrane protein sequences and folds. In conclusion, we suggest a chronology for the evolution of the five extant VKOR clades.     

医院环境中物体表面碳青霉烯耐药鲍曼不动杆菌污染及同源性分析

目的调查某院重点部门物体表面碳青霉烯耐药鲍曼不动杆菌污染情况及其同源性。方法对该院重症监护室(ICU)、急诊重症监护室(EICU)、血液透析室、手术室进行环境卫生学监测,采用肠杆菌科基因间重复序列聚合酶链反应(ERIC-PCR),对ICU、EICU环境中污染的条件致病菌鲍曼不动杆菌进行扩增分型。结果除EICU医务人员手卫生结果达标外,ICU及EICU各检测项目细菌计数均不达标;血液透析室及手术室采样标本均合格。ICU、EICU物体表面共采集标本53份,检出鲍曼不动杆菌7株,检出率为13.21%;此7株菌均为碳青霉烯耐药鲍曼不动杆菌,其中6株基因型相同,与患者痰中分离的鲍曼不动杆菌基因型相同。结论该院重点部门环境中物体表面分离的碳青霉烯耐药鲍曼不动杆菌具有同源性,应加强其环境物体表面清洁与消毒,降低医院感染的发生。     

Design,microwave‐assisted synthesis,biological evaluation and molecular modeling studies of 4‐phenylthiazoles as potent fatty acid amide hydrolase inhibitors

Endocannabinoids, anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG), are endogenous lipids that activate cannabinoid receptors. Activation of these receptors produces anti‐inflammatory and analgesic effects. Fatty acid amide hydrolase (FAAH) is a membrane enzyme that hydrolases endocannabinoids; thus, inhibition of FAAH represents an attractive approach to develop new therapeutics for treating inflammation and pain. Previously, potent rat FAAH inhibitors containing 2‐naphthyl‐ and 4‐phenylthiazole scaffolds were identified, but up to the present time, very little structure–activity relationship studies have been performed on these moieties. We designed and synthesized several analogs containing these structural motifs and evaluated their inhibition potencies against human FAAH enzyme. In addition, we built and validated a homology model of human FAAH enzyme and performed docking experiments. We identified several inhibitors in the low nanomolar range and calculated their ADME predicted values. These FAAH inhibitors represent promising drug candidates for future preclinical in vivo studies.     

Urotensin II induces transactivation of the epidermal growth factor receptor via transient oxidation of SHP-2 in the rat renal tubular cell line NRK-52E

Urotensin-II (UII) is a potent vasoactive peptide that has been implicated in cardiac fibrosis and renal diseases. However, the role played by UII in renal tissues is largely unknown. In this study, we investigated the effects of human UII (hUII) on rat renal proximal tubular cells of the NRK-52E line and the role of Src homology 2-containing phosphotyrosine phosphatase (SHP-2) in the hUII-induced transactivation of the epidermal growth factor receptor (EGFR). Exposure to hUII at low concentrations significantly induced proliferation in NRK-52E cells; this effect was inhibited by treatment with an ERK1/2 inhibitor (PD98059). UII treatment increased the phosphorylation of EGFR and induced the generation of reactive oxygen species (ROS). Treatment of the ROS scavenger N-acetyl-cysteine (NAC) inhibited EGFR transactivation and ERK phosphorylation induced by hUII. SHP-2 was found to interact with EGFR and be transiently oxidized following the hUII treatment. In SHP-2 knockdown cells, UII-induced phosphorylation of EGFR was less influenced by NAC, and significantly suppressed by heparin binding (HB)-EGF neutralizing antibody. Our data suggest that the ROS-mediated oxidation of SHP-2 is essential for the hUII-induced mitogenic pathway in NRK-52E cells.     

Inhibition by Methylprednisolone Acetate Suggests an Indirect Mechanism for TGF-B Induced Angiogenesis

Abstract

Angiogenesis induced by transforming growth factor beta (TGFB) implanted in the rabbit cornea is accorripanied by an influx of inflammatory cells. To determine if the inflammatory cells are the mediators of the neovascularization, they were depleted by local administration of methylprednisolone acetate (MPA). Subconjunctival injections of 16 mg of MPA immediately following implantation of 50 ng of TGFB in the cornea prevented the inflammation and subsequent formation of capillaries. If the injections of MPA were delayed by 48 hr and the inflammatory cells were allowed to enter the cornea, angiogenesis occured, demonstrating that MPA had no adverse effects on the ability of endothelial cells to form capillaries. These results confirm the hypothesis that TGFB induces angiogenesis indirectly by recruiting inflammatory cells capable of stimulating direct angiogenesis.