Selective cleavage of 10-methyl benzo[b]naphtho[2,1-d]thiophene by recombinant Mycobacterium sp. strain

Recombinant Mycobacterium sp. strain MR65 carrying dszABCD genes was used for desulfurization of 10-methylbenzo[b]naphtho[2,1-d]thiophene (10-methyl BNT) in the hexadecane phase. The specific activity was 25% of that of dibenzothiophene (DBT). One of two major metabolites of 10-methyl BNT produced by strain MR65 was identified as 1-methoxy-2-(3-methylphenyl)naphthalene by ¹H and ¹³C NMR. The other major metabolite and two minor metabolites were determined as 1-hydroxy-2-(3-methylphenyl)naphthalene, 2-(2-methoxy-3-methylphenyl)naphthalene and 2-(2-hydroxy-3-methylphenyl)naphthalene, respectively, by HPLC and GC-MS. The production ratio of the two desulfurization metabolite isomers was 0.99:0.01, calculated on the basis of peak GC areas. These results indicated that the C-S bond adjacent to the naphthalene skeleton was selectively cleaved to form the two major compounds.     

Sculpting the cardiac outflow tract

The cardiac outflow tract is the site of anomalies that affect a substantial proportion of individuals with congenital heart defects. The morphogenesis of this site is complex, and requires coordinated development of many cell types and tissues. It is therefore not surprising that developmental mistakes arise here, and that the steps and mechanisms of morphogenesis are still controversial and poorly understood, despite advances in molecular techniques. Recent findings have provided new insight into mechanisms of outflow tract morphogenesis, including clarification of its origins and the fate of cardiomyocytes, as well as invading cell populations. Application of new and old techniques and a wide range of approaches to tackle the unanswered questions about the outflow tract calls for collaboration among investigators from different disciplines including anatomists, physiologists, and molecular biologists.     

A sensitive method for 4-hydroxybutyric acid in urine using gas chromatography-mass spectrometry

4-Hydroxybutyric acid (4HB) was analyzed by gas chromatography-mass spectrometry. Under acidified conditions, 4HB is difficult to detect due to lactonization. Using a urine sample containing 0.01 mg creatinine, we performed trimethylsilyl derivatization without extraction, only adding dimethylsuccinic acid as an internal standard and 10 microl of 0.1 N NaOH methanol solution with adequate evaporation. Urine 4HB levels in a patient with 4-hydroxybutyric aciduria was determined to be 1258 mmol/mol Cr (control, 0.28-2.81 mmol/mol Cr) in this method. Direct derivatization of samples without extraction showed good reproducibility and linearity. Only a small sample of urine was required. Alkalinization by NaOH prevented not only lactonization of 4HB, but also loss of the compounds during evaporation.     

Molecular characterization of the essential response regulator protein YycF in Bacillus subtilis

The response regulator YycF is essential for cell growth in gram-positive bacteria including Bacillus subtilis, Staphylococcus aureus and Streptococcus pneumoniae. To study the function of YycF in the essential process, we characterized a YycF (H215P) mutation that caused temperature-sensitive growth in B. subtilis. The response regulators YycF and YycF (H215P) were analyzed using circular dichroism spectroscopy, whose T(m) values were 56.0 and 45.9 degrees C, respectively, suggesting that YycF (H215P) significantly affects the protein structure with an increase in temperature. Furthermore, using the gel mobility shift assay and DNase I footprinting, we investigated the effect of YycF (H215P) on binding to the YycF box of ftsAZ operon of B. subtilis. The replacement of the histidine 215 with proline resulted in a decrease of the DNA-binding ability of YycF in vitro. In vivo, using Escherichia coli two-hybrid and homodimerization assays, we clarified that His 215 of YycF plays a crucial role in the homodimerization of the protein. Thus the essential genes involved in growth of B. subtilis appear to be regulated by the homodimer of YycF. These results suggest that the YycF dimerization is an excellent target for the discovery of novel antibiotics.     

Expression and localization of P1 promoter-driven hepatocyte nuclear factor-4α (HNF4α) isoforms in human and rats

BACKGROUND: Hepatocyte nuclear factor-4alpha (HNF4alpha; NR2A1) is an orphan member of the nuclear receptor superfamily involved in various processes that could influence endoderm development, glucose and lipid metabolism. A loss-of-function mutation in human HNF4alpha causes one form of diabetes mellitus called maturity-onset diabetes of the young type 1 (MODY1) which is characterized in part by a diminished insulin secretory response to glucose. The expression of HNF4alpha in a variety of tissues has been examined predominantly at the mRNA level, and there is little information regarding the cellular localization of the endogenous HNF4alpha protein, due, in part, to the limited availability of human HNF4alpha-specific antibodies. RESULTS: Monoclonal antibodies have been produced using baculovirus particles displaying gp64-HNF4alpha fusion proteins as the immunizing agent. The mouse anti-human HNF4alpha monoclonal antibody (K9218) generated against human HNF4alpha1/alpha2/alpha3 amino acids 3-49 was shown to recognize not only the transfected and expressed P1 promoter-driven HNF4alpha proteins, but also endogenous proteins. Western blot analysis with whole cell extracts from Hep G2, Huh7 and Caco-2 showed the expression of HNF4alpha protein, but HEK293 showed no expression of HNF4alpha protein. Nuclear-specific localization of the HNF4alpha protein was observed in the hepatocytes of liver cells, proximal tubular epithelial cells of kidney, and mucosal epithelial cells of small intestine and colon, but no HNF4alpha protein was detected in the stomach, pancreas, glomerulus, and distal and collecting tubular epithelial cells of kidney. The same tissue distribution of HNF4alpha protein was observed in humans and rats. Electron microscopic immunohistochemistry showed a chromatin-like localization of HNF4alpha in the liver and kidney. As in the immunohistochemical investigation using K9218, HNF4alpha mRNA was found to be localized primarily to liver, kidney, small intestine and colon by RT-PCR and GeneChip analysis. CONCLUSION: These results suggest that this method has the potential to produce valuable antibodies without the need for a protein purification step. Immunohistochemical studies indicate the tissue and subcellular specific localization of HNF4alpha and demonstrate the utility of K9218 for the detection of P1 promoter-driven HNF4alpha isoforms in humans and in several other mammalian species.     

Establishment of a monoclonal antibody for human LXRα: Detection of LXRα protein expression in human macrophages

Liver X activated receptor alpha (LXRalpha) forms a functional dimeric nuclear receptor with RXR that regulates the metabolism of several important lipids, including cholesterol and bile acids. As compared with RXR, the LXRalpha protein level in the cell is low and the LXRalpha protein itself is very hard to detect. We have previously reported that the mRNA for LXRalpha is highly expressed in human cultured macrophages. In order to confirm the presence of the LXRalpha protein in the human macrophage, we have established a monoclonal antibody against LXRalpha, K-8607. The binding of mAb K-8607 to the human LXRalpha protein was confirmed by a wide variety of different techniques, including immunoblotting, immunohistochemistry, and electrophoretic mobility shift assay (EMSA). By immunoblotting with this antibody, the presence of native LXR protein in primary cultured human macrophage was demonstrated, as was its absence in human monocytes. This monoclonal anti-LXRalpha antibody should prove to be a useful tool in the analysis of the human LXRalpha protein.