Tobacco Plastid Transformation as Production Platform of Lytic Polysaccharide MonoOxygenase Auxiliary Enzymes

Plant biomass is the most abundant renewable resource in nature. In a circular economy perspective, the implementation of its bioconversion into fermentable sugars is of great relevance. Lytic Polysaccharide MonoOxygenases (LPMOs) are accessory enzymes able to break recalcitrant polysaccharides, boosting biomass conversion and subsequently reducing costs. Among them, auxiliary activity of family 9 (AA9) acts on cellulose in synergism with traditional cellulolytic enzymes. Here, we report for the first time, the production of the AA9 LPMOs from the mesophilic Trichoderma reesei (TrAA9B) and the thermophilic Thermoascus aurantiacus (TaAA9B) microorganisms in tobacco by plastid transformation with the aim to test this technology as cheap and sustainable manufacture platform. In order to optimize recombinant protein accumulation, two different N-terminal regulatory sequences were used: 5' untranslated region (5'-UTR) from T7g10 gene (DC41 and DC51 plants), and 5' translation control region (5'-TCR), containing the 5'-UTR and the first 14 amino acids (Downstream Box, DB) of the plastid atpB gene (DC40 and DC50 plants). Protein yields ranged between 0.5 and 5% of total soluble proteins (TSP). The phenotype was unaltered in all transplastomic plants, except for the DC50 line accumulating AA9 LPMO at the highest level, that showed retarded growth and a mild pale green phenotype. Oxidase activity was spectrophotometrically assayed and resulted higher for the recombinant proteins without the N-terminal fusion (DC41 and DC51), with a 3.9- and 3.4-fold increase compared to the fused proteins.

Tryptophan Side-Chain Oxidase Enzyme Suppresses Hepatocellular Carcinoma Growth through Degradation of Tryptophan

Tryptophan metabolism plays a role in the occurrence and development of hepatocellular carcinoma cells. By degrading certain amino acids, tumor growth can be limited while maintaining the body’s normal nutritional requirements. Tryptophan side-chain oxidase (TSO) enzyme can degrade tryptophan, and its inhibitory effect on hepatocellular carcinoma cells is worthy of further study. To investigate the degradation effect on tryptophan, TSO was isolated and purified from qq Pseudomonas. The reaction products were identified with high performance liquid chromatography (HPLC) and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS). De novo sequencing provided the complete amino acid sequence of TSO. The results of CCK-8, colony formation, transwell, and qPCR confirmed that TSO had inhibitory effects on the proliferation and migration of HCCLM3 (human hepatocarcinoma cell line) and HepG2 cells. The results of flow cytometry confirmed its apoptotic activity. In animal experiments, we found that the tumor-suppressive effect was better in the oncotherapy group than the intraperitoneal injection group. The results of immunohistochemistry also suggested that TSO could inhibit proliferation and promote apoptosis. In conclusion, a specific enzyme that can degrade tryptophan and inhibit the growth of hepatoma cells was authenticated, and its basic information was obtained by extraction/purification and amino acid sequencing.

Magnaporthe oryzae as an expression host for the production of the unspecific peroxygenase AaeUPO from the basidiomycete Agrocybe aegerita

The filamentous fungus Magnaporthe oryzae has the potential to be developed as an alternative platform organism for the heterologous production of industrially important enzymes. M. oryzae is easy to handle, fast-growing and unlike yeast, posttranslational modifications like N-glycosylations are similar to the human organism. Here, we established M. oryzae as a host for the expression of the unspecific peroxygenase from the basidiomycete Agrocybe aegerita (AaeUPO). Note, UPOs are attractive biocatalysts for selective oxyfunctionalization of non-activated carbon-hydrogen bonds. To improve and simplify the isolation of AaeUPO in M. oryzae, we fused a Magnaporthe signal peptide for protein secretion and set it under control of the strong EF1α-promoter. The success of the heterologous production of full-length AaeUPO in M. oryzae and the secretion of the functional enzyme was confirmed by a peroxygenase-specific enzyme assay. These results offer the possibility to establish the filamentous ascomycete M. oryzae as a broad applicable alternative expression system.

Overexpression of Human Aspartyl (Asparaginyl) β-hydroxylase in NSCLC: Its Diagnostic Value by Means of Exosomes of Bronchoalveolar Lavage

The human aspartyl β-hydroxylase (ASPH) is overexpressed in tumor tissues. Bronchoalveolar lavage (BAL) is a diagnostic procedure for infections and malignancies. The aim of this study was to investigate whether tumor exosomes carrying ASPH gene marker were present in bronchoalveolar fluid of patients with non-small cell lung cancer (NSCLC). A tissue microarray analysis was applied to explore the expression of ASPH in different histologic NSCLC. The human NSCLC cell lines and normal bronchial cell lines were used to study exosomal ASPH exprerssion. A total of 27 NSCLC, 21 benign tumor, and 15 healthy controls underwent BAL. Immunohistochemistry was performed to study the ASPH expression in malignant and normal lung tissues. The expression characteristics of ASPH in different NSCLC and normal bronchial cells and pneumocytes were confirmed by cell blocks. A reverse transcription-quantitative polymerase chain reaction was carried out to study the levels of exosomal ASPH expression. Immunohistochemical staining of tissue microarray demonstrated that overexpression of ASPH was found in NSCLC tissues including adenocarcinoma, large cell carcinoma, and squamous cell carcinoma, but absent in adjacent normal tissues. All NSCLC specimens exhibited high levels of ASPH immunoreactivity, while nonmalignant and normal lung tissues exhibited a very low level of expression. Overexpression of ASPH was found in exosomes from NSCLC cell lines but absent from the normal bronchial cell line NL-20. ASPH level from BAL exosomes was significantly increased in NSCLC patients compared with that from nonmalignant or health group. Our method of isolation of BAL exosomes was easily performed in the clinical laboratory. BAL exosomal ASPH can be a potential biomarker for NSCLC diagnosis.

A modular two yeast species secretion system for the production and preparative application of unspecific peroxygenases

Fungal unspecific peroxygenases (UPOs) represent an enzyme class catalysing versatile oxyfunctionalisation reactions on a broad substrate scope. They are occurring as secreted, glycosylated proteins bearing a haem-thiolate active site and rely on hydrogen peroxide as the oxygen source. However, their heterologous production in a fast-growing organism suitable for high throughput screening has only succeeded once-enabled by an intensive directed evolution campaign. We developed and applied a modular Golden Gate-based secretion system, allowing the first production of four active UPOs in yeast, their one-step purification and application in an enantioselective conversion on a preparative scale. The Golden Gate setup was designed to be universally applicable and consists of the three module types: i) signal peptides for secretion, ii) UPO genes, and iii) protein tags for purification and split-GFP detection. The modular episomal system is suitable for use in Saccharomyces cerevisiae and was transferred to episomal and chromosomally integrated expression cassettes in Pichia pastoris. Shake flask productions in Pichia pastoris yielded up to 24 mg/L secreted UPO enzyme, which was employed for the preparative scale conversion of a phenethylamine derivative reaching 98.6 % ee. Our results demonstrate a rapid, modular yeast secretion workflow of UPOs yielding preparative scale enantioselective biotransformations.

Characterization of a broadly specific cadaverine N-hydroxylase involved in desferrioxamine B biosynthesis in Streptomyces sviceus

N-hydroxylating flavin-dependent monooxygenases (FMOs) are involved in the biosynthesis of hydroxamate siderophores, playing a key role in microbial virulence. Herein, we report the first structural and kinetic characterization of a novel alkyl diamine N-hydroxylase DesB from Streptomyces sviceus (SsDesB). This enzyme catalyzes the first committed step in the biosynthesis of desferrioxamine B, a clinical drug used to treat iron overload disorders. X-ray crystal structures of the SsDesB holoenzyme with FAD and the ternary complex with bound NADP+ were solved at 2.86 Å and 2.37 Å resolution, respectively, providing a structural view of the active site environment. SsDesB crystallized as a tetramer and the structure of the individual protomers closely resembles the structures of homologous N-hydroxylating FMOs from Erwinia amylovora (DfoA), Pseudomonas aeruginosa (PvdA), and Aspergillus fumigatus (SidA). Using NADPH oxidation, oxygen consumption, and product formation assays, kinetic parameters were determined for various substrates with SsDesB. SsDesB exhibited typical saturation kinetics with substrate inhibition at high concentrations of NAD(P)H as well as cadaverine. The apparent kcat values for NADPH in steady-state NADPH oxidation and oxygen consumption assays were 0.28 ± 0.01 s-1 and 0.24 ± 0.01 s-1, respectively. However, in product formation assays used to measure the rate of N-hydroxylation, the apparent kcat for NADPH (0.034 ± 0.008 s-1) was almost 10-fold lower under saturating FAD and cadaverine concentrations, reflecting an uncoupled reaction, and the apparent NADPH KM was 33 ± 24 μM. Under saturating FAD and NADPH concentrations, the apparent kcat and KM for cadaverine in Csaky assays were 0.048 ± 0.004 s-1 and 19 ± 9 μM, respectively. SsDesB also N-hydroxylated putrescine, spermidine, and L-lysine substrates but not alkyl (di)amines that were branched or had fewer than four methylene units in an alkyl chain. These data demonstrate that SsDesB has wider substrate scope compared to other well-studied ornithine and lysine N-hydroxylases, making it an amenable biocatalyst for the production of desferrioxamine B, derivatives, and other N-substituted products.

Resveratrol inhibits the tumor migration and invasion by upregulating TET1 and reducing TIMP2/3 methylation in prostate carcinoma cells

BACKGROUND

Recently, resveratrol (Res) has been suggested to suppress the migration and invasion of prostate cancer (PCa). In the present study, we aimed to investigate the effects of Res on genomic DNA methylation, as well as the migration and invasion of PCa cells.

METHODS

The suppression by Res of the growth of PCa cells was verified through a cytotoxicity assay. In addition, the effects of Res on 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), and ten-eleven translocation 1 (TET1) levels were assessed, and the cell migration and invasion were also determined. The expressions of TET1, tissue inhibitor of metalloproteinases (TIMP) 2, TIMP3, MMP2, and MMP9 were detected through Western blot analysis. Afterward, TET1 was silenced using lentiviral short hairpin RNA to examine the effect of TET1 on the Res-triggered inhibition of migration and invasion of PCa cells.

RESULTS

Our results showed that Res upregulated the 5hmC and TET1 levels and downregulated the 5mC level. Moreover, Res also inhibited the migration and invasion of PCa cells, promoted the demethylation of TIMP2 and TIMP3 to upregulate their expressions, and suppressed the expressions of MMP2 and MMP9. The silencing of TET1 in the presence of Res showed that Res could exert its effect through TET1.

CONCLUSIONS

Our findings indicated that Res inhibited the migration and invasion of PCa cells via the TET1/TIMP2/TIMP3 pathway, which might potentially serve as a target for the treatment of PCa.

Transcriptome profiling reveals the molecular processes for survival of Lysinibacillus fusiformis strain 15-4 in petroleum environments

A bacterial strain designated Lysinibacillus fusiformis 15-4 was isolated from oil-free soil on the Qinghai-Tibet Plateau, which can grow well utilizing petroleum hydrocarbons as a carbon source at a lower temperature. To deeply characterize the molecular adaptations and metabolic processes of this strain when grown in a petroleum-containing environment, transcriptome analysis was performed. A total of 4664 genes and the expression of 3969 genes were observed in strain 15-4. When the strain was grown in petroleum-containing medium, 2192 genes were significantly regulated, of which 1312 (60%) were upregulated and 880 (40%) were downregulated. This strain degraded and adapted to petroleum via modulation of diverse molecular processes, including improvements in transporter activity, oxidoreductase/dehydrogenase activity, two-component system/signal transduction, transcriptional regulation, fatty acid catabolism, amino acid metabolism, and environmental stress responses. Many strain-specific genes were involved in the oxidation of hydrocarbon compounds, such as several luciferase family alkane monooxygenase genes, flavin-utilizing monooxygenase family genes, and flavoprotein-like family alkanesulfonate monooxygenase genes. Several cold shock protein genes were also induced suggesting adaptation to cold environments and the potential for petroleum degradation at low temperatures. The results obtained in this study may broaden our understanding of molecular adaptation of bacteria to hydrocarbon-containing environments and may provide valuable data for further study of L. fusiformis.

Characterization of the Ornithine Hydroxylation Step in Albachelin Biosynthesis

N-Hydroxylating monooxygenases (NMOs) are involved in siderophore biosynthesis. Siderophores are high affinity iron chelators composed of catechol and hydroxamate functional groups that are synthesized and secreted by microorganisms and plants. Recently, a new siderophore named albachelin was isolated from a culture of Amycolatopsis alba growing under iron-limiting conditions. This work focuses on the expression, purification, and characterization of the NMO, abachelin monooxygenase (AMO) from A. alba. This enzyme was purified and characterized in its holo (FAD-bound) and apo (FAD-free) forms. The apo-AMO could be reconstituted by addition of free FAD. The two forms of AMO hydroxylate ornithine, while lysine increases oxidase activity but is not hydroxylated and display low affinity for NADPH.

Zebrafish have an ethanol-inducible hepatic 4-nitrophenol hydroxylase that is not CYP2E1-like

Zebrafish are an attractive model organism for toxicology; however, an important consideration in translating between species is xenobiotic metabolism/bioactivation. CYP2E1 metabolizes small hydrophobic molecules, e.g. ethanol, cigarette smoke, and diesel exhaust components. CYP2E1 is thought to only be conserved in mammals, but recent reports identified homologous zebrafish cytochrome P450s. Herein, ex vivo biochemical measurements show that unlike mammals, zebrafish possess a low-affinity 4-nitrophenol hydroxylase (K_m ∼0.6 mM) in hepatic microsomes and mitochondria that is inducible only 1.5- to 2-fold by ethanol and is insensitive to 4-methylpyrazole inhibition. In closing, we suggest creating improved models to study CYP2E1 in zebrafish.

[Synthesis of L-lactate oxidaze in yeast Yarrowia lipolytica during submerged cultivation]

The biosynthesis of L-lactate oxidase in the Yarrowia lipolytica yeast during submerged cultivation in laboratory bioreactors ANKUM-2M has been studied. It has been shown under optimal conditions of yeast cultivation with L-lactate that 24.5 U/L enzyme accumulated in the medium and the yield was 2.0 U/(L h). An increase in the biosynthesis of L-lactate oxidase to 75 U/L and the yield to 3.2 U/(L h) was achieved in the medium with L-lactate (1%) and glucose (2%). The enzyme was purified 251 times to homogeneity by hydrophobic and ion exchange chromatography state with a yield of 45% and a specific activity of 55.3 U/mg. Techniques of gel filtration and denaturing electrophoresis showed that L-lactate oxidase from Y. lipolytica is a tetramer with a molecular mass of 200–230 kDa. The enzyme showed a strict specificity to L-lactate and did not oxidize fumarate, pyruvate, succinate, ascorbate, dihydroxyacetone, glycolate, D-lactate, D, L-2-hydroxybutyrate and D, L-alanine or D-serine.

Molecular cloning of melatonin 3-hydroxylase and its production of cyclic 3-hydroxymelatonin in rice (Oryza sativa)

Melatonin is metabolized in animals to cyclic 3-hydroxymelatonin (3-OHM) not by an enzymatic pathway, but by interaction with hydroxyl radicals. The production of 3-OHM in animals suggests the possible presence of 3-OHM in plants. Prior to the identification of 3-OHM in plants, we directly cloned the corresponding gene(s) responsible for 3-OHM synthesis using Escherichia coli library strains expressing genes belonging to the 2-oxoglutarate-dependent dioxygenase (2-ODD) superfamily from rice. Three of 35 E. coli library strains supplemented with 1 mmol/L melatonin were found to produce 3-OHM in their extracellular medium, suggestive of three 2-ODD genes involved in 3-OHM production. The purified recombinant 2-ODD 11, 2-ODD 26, and 2-ODD 33 proteins were shown to catalyze the metabolism of melatonin to 3-OHM, with 2-ODD 11 showing the highest melatonin 3-hydroxylase (M3H) catalytic activity. Consistent with the presence of M3H genes, rice leaves supplemented with 5 mmol/L melatonin produced 3-OHM [233 μg/g fresh weight (FW)], 2-hydroxymelatonin (21 μg/g FW), and N¹ -acetyl-N² -formyl-5-methoxykynuramine (5 μg/g FW). Three M3H transcripts were induced upon the treatment of rice leaves with cadmium followed by an increase in M3H enzyme activity. Cloning of M3H genes in plants has paved the way for the studies of melatonin in plants in terms of its multiple physiological roles.

The QTL GNP1 Encodes GA20ox1, Which Increases Grain Number and Yield by Increasing Cytokinin Activity in Rice Panicle Meristems

Cytokinins and gibberellins (GAs) play antagonistic roles in regulating reproductive meristem activity. Cytokinins have positive effects on meristem activity and maintenance. During inflorescence meristem development, cytokinin biosynthesis is activated via a KNOX-mediated pathway. Increased cytokinin activity leads to higher grain number, whereas GAs negatively affect meristem activity. The GA biosynthesis genes GA20oxs are negatively regulated by KNOX proteins. KNOX proteins function as modulators, balancing cytokinin and GA activity in the meristem. However, little is known about the crosstalk among cytokinin and GA regulators together with KNOX proteins and how KNOX-mediated dynamic balancing of hormonal activity functions. Through map-based cloning of QTLs, we cloned a GA biosynthesis gene, Grain Number per Panicle1 (GNP1), which encodes rice GA20ox1. The grain number and yield of NIL-GNP1^TQ were significantly higher than those of isogenic control (Lemont). Sequence variations in its promoter region increased the levels of GNP1 transcripts, which were enriched in the apical regions of inflorescence meristems in NIL-GNP1^TQ. We propose that cytokinin activity increased due to a KNOX-mediated transcriptional feedback loop resulting from the higher GNP1 transcript levels, in turn leading to increased expression of the GA catabolism genes GA2oxs and reduced GA₁ and GA₃ accumulation. This rebalancing process increased cytokinin activity, thereby increasing grain number and grain yield in rice. These findings uncover important, novel roles of GAs in rice florescence meristem development and provide new insights into the crosstalk between cytokinin and GA underlying development process.

Grain number per panicle, a valuable agronomic trait for rice yield improvement, is profoundly affected by reproductive meristem activity. This activity, in turn, is controlled by transcriptional and plant hormone regulators, especially KNOX proteins and cytokinins. However, little is known about the roles of GAs in these processes in rice and how the regulatory network functions due to the complexity of crosstalk between plant hormone regulators. In this study, we identify a novel GA biosynthesis gene in rice and demonstrate its role in improving grain number and grain yield. We also propose that the KNOX-mediated cytokinin-GA activity rebalancing mechanisms regulate inflorescence meristem development and maintenance processes, providing a possible tool for high-yield rice breeding.

The Protein Kinase CK2 Mediates Cross-Talk between Auxin- and Salicylic Acid-Signaling Pathways in the Regulation of PINOID Transcription

The protein kinase CK2 is a ubiquitous and highly conserved enzyme, the activity of which is vital for eukaryotic cells. We recently demonstrated that CK2 modulates salicylic acid (SA) homeostasis in Arabidopsis thaliana, and that functional interplay between CK2 and SA sustains transcriptional expression of PIN-FORMED (PIN) genes. In this work, we show that CK2 also plays a key role in the transcriptional regulation of PINOID (PID), an AGC protein kinase that modulates the apical/basal localization of auxin-efflux transporters. We show that PID transcription is up-regulated by auxin and by SA and that CK2 is involved in both pathways. On the one hand, CK2 activity is required for proteosome-dependent degradation of AXR3, a member of the AUX/IAA family of auxin transcriptional repressors that must be degraded to activate auxin-responsive gene expression. On the other hand, the role of CK2 in SA homeostasis and, indirectly, in SA-driven PID transcription, was confirmed by using Arabidopsis NahG transgenic plants, which cannot accumulate SA. In conclusion, our results evidence a role for CK2 as a functional link in the negative cross-talk between auxin- and SA-signaling.

Biosynthesis of 1,2-dihydroxydibenzofuran by magnetically immobilized cells of Escherichia coli expressing phenol hydroxylase in liquid-liquid biphasic systems

Escherichia coli cells expressing phenol hydroxylase (designated as PHIND) were used to biosynthesize 1,2-dihydroxydibenzofuran (1,2-dihydroxyDBF) from dibenzofuran (DBF). The pathway of DBF biotransformation by strain PHIND was proposed, in which DBF was initially monohydroxylated at C-1 and C-4 positions to produce 1- and 4-hydroxyDBF, then underwent successive hydroxylation to yield 1,2- and 3,4-dihydroxyDBF, of which 1,2-dihydroxyDBF was identified for the first time. Magnetically immobilized cells of strain PHIND in biphasic systems with dodecane as the solvent presented highest biosynthesis activity for 1,2-dihydroxyDBF, which was a 6.5-fold improvement compared to biosynthesis in aqueous system. The recycling experiments demonstrated that magnetically immobilized cells exhibited higher biosynthesis activity for 1,2-dihydroxyDBF than that by nonmagnetically immobilized cells during five cycles in biphasic systems. These works support the development of an efficient biosynthesis process using magnetically immobilized cells in biphasic systems and provide a promising technique for improving the productivity in 1,2-dihydroxyDBF biosynthesis.

Expression of recombinant human bifunctional peptidylglycine α-amidating monooxygenase in CHO cells and its use for insulin analogue modification

The availability of catalytically active peptidylglycine α-amidating monooxygenase (PAM) should provide the means to examine its potential use for the chemienzymatic synthesis of bioactive peptides for the purpose of pharmacological studies. Hypoglycemic activity is one of the most important features of insulin derivatives. Insulin glargine amide was found to show a time/effect profile which is distinctly more flat and thus more advantageous than insulin glargine itself. The aim of the study was to obtain recombinant PAM and use it for insulin analogue amidation. We stably expressed a recombinant PAM in CHO dhfr-cells in culture. Recombinant PAM was partially purified by fractional ammonium sulphate precipitation and ion-exchange chromatography. The enzyme was used to modify glycine-extended A22(G)-B31(K)-B32(R) human insulin analogue (GKR). Alpha-amidated insulin was analyzed by HPLC and mass spectrometry. Hypoglycemic activity of amidated and non-amidated insulin was compared. The pharmacodynamic effect was based on glucose concentration measurement in Wistar rats with hyperglycemia induced by streptozotocin. The overall glycemic profile up to 36 h was evaluated after subcutaneous single dosing at a range of 2.5-7.5 U/kg b.w. The experiment on rats confirmed with a statistical significance (P < 0.05) hypoglycemic activity of GKR-NH2 in comparison to a control group receiving 0.9% NaCl. Characteristics for GKR-NH2 profile was a rather fast beginning of action (0.5-2.0 h) and quite prolonged return to initial values. GKR-NH2 is a candidate for a hypoglycemic drug product in diabetes care. In addition, this work also provides a valuable alternative method for preparing any other recombinant bioactive peptides with C-terminal amidation.

Phenotype of Arabidopsis thaliana semi-dwarfs with deep roots and high growth rates under water-limiting conditions is independent of the GA5 loss-of-function alleles

BACKGROUND AND AIMS

The occurrence of Arabidopsis thaliana semi-dwarf accessions carrying inactive alleles at the gibberellin (GA) biosynthesis GA5 locus has raised the question whether there are pleiotropic effects on other traits at the root level, such as rooting depth. In addition, it is unknown whether semi-dwarfism in arabidopsis confers a growth advantage under water-limiting conditions compared with wild-type plants. The aim of this research was therefore to investigate whether semi-dwarfism has a pleiotropic effect in the root system and also whether semi-dwarfs might be more tolerant of water-limiting conditions.

METHODS

The root systems of different arabidopsis semi-dwarfs and GA biosynthesis mutants were phenotyped in vitro using the GROWSCREEN-ROOT image-based software. Semi-dwarfs were phenotyped together with tall, near-related accessions. In addition, root phenotypes were investigated in soil-filled rhizotrons. Rosette growth trajectories were analysed with the GROWSCREEN-FLUORO setup based on non-invasive imaging.

KEY RESULTS

Mutations in the early steps of the GA biosynthesis pathway led to a reduction in shoot as well as root size. Depending on the genetic background, mutations at the GA5 locus yielded phenotypes characterized by decreased root length in comparison with related wild-type ones. The semi-dwarf accession Pak-3 showed the deepest root system both in vitro and in soil cultivation experiments; this comparatively deep root system, however, was independent of the ga5 loss-of-function allele, as shown by co-segregation analysis. When the accessions were grown under water-limiting conditions, semi-dwarf accessions with high growth rates were identified.

CONCLUSIONS

The observed diversity in root system growth and architecture occurs independently of semi-dwarf phenotypes, and is probably linked to a genetic background effect. The results show that there are no clear advantages of semi-dwarfism at low water availability in arabidopsis.

Transgenic poplar expressing Arabidopsis YUCCA6 exhibits auxin-overproduction phenotypes and increased tolerance to abiotic stress

YUCCA6, a member of the YUCCA family of flavin monooxygenase-like proteins, is involved in the tryptophan-dependent IAA biosynthesis pathway and responses to environmental cues in Arabidopsis. However, little is known about the role of the YUCCA pathway in auxin biosynthesis in poplar. Here, we generated transgenic poplar (Populus alba × P. glandulosa) expressing the Arabidopsis YUCCA6 gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SY plants). Three SY lines (SY7, SY12 and SY20) were selected based on the levels of AtYUCCA6 transcript. SY plants displayed auxin-overproduction morphological phenotypes, such as rapid shoot growth and retarded main root development with increased root hair formation. In addition, SY plants had higher levels of free IAA and early auxin-response gene transcripts. SY plants exhibited tolerance to drought stress, which was associated with reduced levels of reactive oxygen species. Furthermore, SY plants showed delayed hormone- and dark-induced senescence in detached leaves due to higher photosystem II efficiency and less membrane permeability. These results suggest that the conserved IAA biosynthesis pathway mediated by YUCCA family members exists in poplar.

Improvement of catechin production in Escherichia coli through combinatorial metabolic engineering

Reconstruction of highly efficient biosynthesis pathways is essential for the production of valuable plant secondary metabolites in recombinant microorganisms. In order to improve the titer of green tea catechins in Escherichia coli, combinatorial strategies were employed using the ePathBrick vectors to express the committed catechin pathway: flavanone 3β-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), and leucoanthocyanidin reductase (LAR). Three F3H, three DFR, and two LAR genes originating from different plant species were selected and synthesized, to create 18 pathway variants to be screened in E. coli. Constructs containing F3H(syn) originally from Camellia sinensis, DFR(syn) from Anthurium andraeanum, C. sinensis, or Fragaria ananass, and LAR(syn) from Desmodium uncinatum (p148, p158 and p168) demonstrated high conversion efficiency with either eriodictyol or naringenin as substrate. A highly efficient construct was created by assembling additional copies of DFR(syn) and LAR(syn) enabling a titer of 374.6 ± 43.6 mg/L of (+)-catechin. Improving the NADPH availability via the ΔpgiΔppc mutation, BLΔpgiΔppc-p148 produced the highest titer of catechin at 760.9 ± 84.3 mg/L. After utilizing a library of scaffolding proteins, the strain BLΔpgiΔppc-p168-759 reached the highest titer of (+)-catechin of 910.9 ± 61.3 mg/L from 1.0 g/L of eriodictyol in batch culture with M9 minimal media. The impact of oxygen availability on the biosynthesis of catechin was also investigated.

Δ(9)-THC modulation of fatty acid 2-hydroxylase (FA2H) gene expression: possible involvement of induced levels of PPARα in MDA-MB-231 breast cancer cells

We recently reported that Δ(9)-tetrahydrocannabinol (Δ(9)-THC), a major cannabinoid component in Cannabis Sativa (marijuana), significantly stimulated the expression of fatty acid 2-hydroxylase (FA2H) in human breast cancer MDA-MB-231 cells. Peroxisome proliferator-activated receptor α (PPARα) was previously implicated in this induction. However, the mechanisms mediating this induction have not been elucidated in detail. We performed a DNA microarray analysis of Δ(9)-THC-treated samples and showed the selective up-regulation of the PPARα isoform coupled with the induction of FA2H over the other isoforms (β and γ). Δ(9)-THC itself had no binding/activation potential to/on PPARα, and palmitic acid (PA), a PPARα ligand, exhibited no stimulatory effects on FA2H in MDA-MB-231 cells; thus, we hypothesized that the levels of PPARα induced were involved in the Δ(9)-THC-mediated increase in FA2H. In support of this hypothesis, we herein demonstrated that; (i) Δ(9)-THC activated the basal transcriptional activity of PPARα in a concentration-dependent manner, (ii) the concomitant up-regulation of PPARα/FA2H was caused by Δ(9)-THC, (iii) PA could activate PPARα after the PPARα expression plasmid was introduced, and (iv) the Δ(9)-THC-induced up-regulation of FA2H was further stimulated by the co-treatment with L-663,536 (a known PPARα inducer). Taken together, these results support the concept that the induced levels of PPARα may be involved in the Δ(9)-THC up-regulation of FA2H in MDA-MB-231 cells.

[Synthesis and localization of L-lactate oxidase in yeasts]

Conditions for L-lactate oxidase synthesis by the yeast Yarrowia lpolytica were investigated. The enzyme was found to be synthesized during growth on L-lactate in the exponential growth phase. L-lactate oxidase synthesis was observed, also on glucose after adaptation to stress conditions (oxidative or thermal stress) r during the stationary growth phase after glucose consumption. The cells grown on L-lactate exhibited high levels of antioxidant enzymes (catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione reductase), which exceeded those of glucose-grown cells. The ultrastructure of L-lactate-grown cellsand of those grown on glucose and adapted to various stress.conditions was also found to besimilar, with increased mitochondria, elevated number and size ofperoxisomes, and formation of lipid and polyphosphate inclusions. In order to determine the intracellular localization of L-lactate oxidase, the cells were disintegrated by the lytic enzyme complex from Helix pomatia. Centrifugation of the homogenate in Percoll gradient resulted in the isolation of purified fractions of the native mitochondria and peroxisomes. L-Lactate oxidase was shown to be localized in peroxisomes.

[Expression of the F3h gene in various wheat organs]

In plants, the F3h gene encodes akey enzyme of flavonoid biosynthesis pathway, flavanone 3-hydroxylase. In most plant species, F3h is a single-copy gene, whereas in the genome of bread wheat (Triticum aestivum L., 2n = 6x = 42, BBAADD), four copies of this gene were found. Using RT-PCR, transcription of these copies was studied in various organs of several wheat genotypes. Three homoeologous copies (F3h-A1, F3h-B1, F3h-D1) manifested similar expression patterns and were specifically transcribed in caryopsis pericarp, culm, coleoptile and leaf colored with anthocyanins. The paralogous copy F3h-B2 in the B-genome was expressed only in wheat roots and probably is involved in biosynthesis of some uncolored flavonoid compounds unrelated to anthocyanin biosynthesis.

[The effect of berberine administration of evaluation of the functional state of rat liver after ligation of common bile duct]

On the eighth day after ligation of the common bile duct in rats a significant increase in the serum content of total lipids, cholesterol bilirubin and ALT, alkaline phosphatase, and gamma-glutamyltransferase was observed. In the microsomal fraction there was a marked decrease in the content and activity of microsomal monooxygenases. Introperitoneal injection of berberine (10 mg/kg) for 6 days caused a partial normalization of permeability of hepatocytes plasma membranes and activity microsomal flavin-containing monooxygenases. It is suggested that berberine is a substrate and inducer of flavin-containing monooxygenases. Membrane-stabilizing effect of berberine is probably realized at the level of inhibition of prooxidant status of liver cells.

Regulation of expression of deoxyhypusine hydroxylase (DOHH), the enzyme that catalyzes the activation of eIF5A, by miR-331-3p and miR-642-5p in prostate cancer cells

The enzyme deoxyhypusine hydroxylase (DOHH) catalyzes the activation of eukaryotic translation initiation factor (eIF5A), a protein essential for cell growth. Using bioinformatic predictions and reporter gene assays, we have identified a 182-nt element within the DOHH 3'-untranslated region (3'-UTR) that contains a number of target sites for miR-331-3p and miR-642-5p. Quantitative RT-PCR studies demonstrated overexpression of DOHH mRNA and underexpression of miR-331-3p and miR-642-5p in several prostate cancer cell lines compared with normal prostate epithelial cells. Transient overexpression of miR-331-3p and/or miR-642-5p in DU145 prostate cancer cells reduced DOHH mRNA and protein expression and inhibited cell proliferation. We observed synergistic growth inhibition with the combination of miR-331-3p and miR-642-5p and mimosine, a pharmacological DOHH inhibitor. Finally, we identified a significant inverse relationship between the expression of miR-331-3p or miR-642-5p and DOHH in a cohort of human prostate cancer tissues. Our results suggest a novel role for miR-331-3p and miR-642-5p in the control of prostate cancer cell growth via the regulation of DOHH expression and eIF5A activity.

Activation of genes involved in xenobiotic metabolism is a shared signature of mouse models with extended lifespan

Xenobiotic metabolism has been proposed to play a role in modulating the rate of aging. Xenobiotic metabolizing enzymes (XME) are expressed at higher levels in calorically restricted mice (CR) and in GH/IGF-I-deficient, long-lived mutant mice. In this study, we show that many phase I XME genes are similarly upregulated in additional long-lived mouse models, including "crowded litter" (CL) mice, whose lifespan has been increased by food restriction limited to the first 3 wk of life, and in mice treated with rapamycin. Induction in the CL mice lasts at least through 22 mo of age, but induction by rapamycin is transient for many of the mRNAs. Cytochrome P-450s, flavin monooxygenases, hydroxyacid oxidase, and metallothioneins were found to be significantly elevated in similar proportions in each of the models of delayed aging tested, whether these were based on mutation, diet, drug treatment, or transient early intervention. The same pattern of mRNA elevation could be induced by 2 wk of treatment with tert-butylhydroquinone, an oxidative toxin known to activate Nrf2-dependent target genes. These results suggest that elevation of phase I XMEs is a hallmark of long-lived mice and may facilitate screens for agents worth testing in intervention-based lifespan studies.

Comparative analysis of β-carotene hydroxylase genes for astaxanthin biosynthesis

Astaxanthin (3,3'-dihydroxy-4,4'-diketo-β-carotene) (1) is a carotenoid of significant commercial value due to its superior antioxidant potential, application as a component of animal feeds, and ongoing research that links its application to the treatment and prevention of human pathologies. The high commercial cost of 1 is also based upon its complex synthesis. Chemical synthesis has been demonstrated, but produces a mixture of stereoisomers with limited applications. Production from biological sources is limited to natural producers with complex culture requirements. The biosynthetic pathway for 1 is well studied; however, questions remain that prevent optimized production in heterologous systems. Presented is a direct comparison of 12 β-carotene (2) hydroxylases derived from archaea, bacteria, cyanobacteria, and plants. Expression in Escherichia coli enables a comparison of catalytic activity with respect to zeaxanthin (3) and 1 biosynthesis. The most suitable β-carotene hydroxylases were subsequently expressed from an efficient dual expression vector, enabling 1 biosynthesis at levels up to 84% of total carotenoids. This supports efficient 1 biosynthesis by balanced expression of β-carotene ketolase and β-carotene hydroxylase genes. Moreover, our work suggests that the most efficient route for astaxanthin biosynthesis proceeds by hydroxylation of β-carotene to zeaxanthin, followed by ketolation.

Overexpression of the HIF hydroxylases PHD1, PHD2, PHD3 and FIH are individually and collectively unfavorable prognosticators for NSCLC survival

Introduction

Hypoxia induced factors (HIFs) are at the heart of the adaptive mechanisms cancer cells must implement for survival. HIFs are regulated by four hydroxylases; Prolyl hydroxylase (PHD)-1,-2,-3 and factor inhibiting HIF (FIH). We aimed to investigate the prognostic impact of these oxygen sensors in NSCLC.

Methods

Tumor tissue samples from 335 resected stages I to IIIA NSCLC patients was obtained and tissue microarrays (TMAs) were constructed. Hydroxylase expression was evaluated by immunohistochemistry.

Principal Findings

There was scorable expression for all HIF hydroxylases in tumor cells, but not in stroma. In univariate analyses, high tumor cell expression of all the HIF hydroxylases were unfavorable prognosticators for disease-specific survival (DSS); PHD1 (P = 0.023), PHD2 (P = 0.013), PHD3 (P = 0.018) and FIH (P = 0.033). In the multivariate analyses we found high tumor cell expression of PHD2 (HR = 2.03, CI 95% 1.20–3.42, P = 0.008) and PHD1 (HR = 1.45, CI 95% 1.01–2.10, P = 0.047) to be significant independent prognosticators for DSS. Besides, there was an additive prognostic effect by the increasing number of highly expressed HIF hydroxylases. Provided none high expression HIF hydroxylases, the 5-year survival was 80% vs. 23% if all four were highly expressed (HR = 6.48, CI 95% 2.23–18.8, P = 0.001).

Conclusions

HIF hydroxylases are, in general, poor prognosticators for NSCLC survival. PHD1 and PHD2 are independent negative prognostic factors in NSCLC. Moreover, there is an additive poor prognostic impact by an increasing number of highly expressed HIF hydroxylases.

[Expression of human aspartyl beta-hydroxylase and preparation of its monoclonal antibody]

We investigated the mechanism of human aspartyl beta-hydroxylase (HAAH) in early diagnosis of tumors. The encoding gene of HAAH was cloned from the hepatic carcinoma by RT-PCR and expressed as a fused protein in the prokaryotic vector pBV-IL1. The expressed HAAH was purified by Ni(2+)-NTA purification column and the purified protein was then used to immunize Balb/c mice. Three hybridoma cell lines (respectively designated H3/E10, E4/F12 and G4/D8) stably expressing the monoclonal antibody specific to HAAH fusion protein were obtained. The specificity and sensitivity of the monoclonal antibody were assessed by indirect enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. Finally, the monoclonal antibody expressed by H3/E10 cell line was used to detect the expression of HAAH in several tumor cell lines by indirect immuno-fluorescence, and the specific fluorescence was observed. In conclusion, this study successfully constructed the recombinant prokaryotic vector pBV-IL1-HAAH and prepared HAAH-specific monoclonal antibody for further study of the structure and function of the protein. The result may also lay solid foundation for the research of the molecular mechanism of HAAH in early diagnosis of tumors.

Regulation of the Marinomonas mediterranea antimicrobial protein lysine oxidase by L-lysine and the sensor histidine kinase PpoS

Some Gram-negative bacteria express a novel enzyme with lysine-epsilon-oxidase (LOD) activity (EC 1.4.3.20). The oxidation of l-Lys generates, among other products, hydrogen peroxide, which confers antimicrobial properties to this kind of enzyme and has been shown to be involved in cell death during biofilm development and differentiation. In addition to LOD, the melanogenic marine bacterium Marinomonas mediterranea, which forms part of the microbiota of the marine plant Posidonia oceanica, expresses two other oxidases of biotechnological interest, a multicopper oxidase, PpoA, with laccase activity and a tyrosinase named PpoB, which is responsible for melanin synthesis. By using both lacZ fusions with the lodAB promoter and quantitative reverse transcription-PCR (qRT-PCR), this study shows that the hybrid sensor histidine kinase PpoS regulates LOD activity at the transcriptional level. Although PpoS also regulates PpoA and PpoB, in this case, the regulatory effect cannot be attributed only to a transcriptional regulation. Further studies indicate that LOD activity is induced at the posttranscriptional level by l-Lys as well as by two structurally similar compounds, l-Arg and meso-2,6-diaminopimelic acid (DAP), neither of which is a substrate of the enzyme. The inducing effect of these compounds is specific for LOD activity since PpoA and PpoB are not affected by them. This study offers, for the first time, insights into the mechanisms regulating the synthesis of the antimicrobial protein lysine-epsilon-oxidase in M. mediterranea, which could be important in the microbial colonization of the seagrass P. oceanica.

[Cloning, heterologous expression and purification of a 3-ketosteroid-9alpha-hydroxylase (KSH) from Mycobacterium sp. NwIB-01]

3-ketosteroid-9alpha-hydroxylase (KSH), a key enzyme in the microbial steroid degradation, is highly valuable for the production of some steroid drugs. Degenerate primers were designed by comparing the ksh from Rhodococcus erythropolis SQ1 and its homologous sequences in the reported genome of Mycobacteria. Subsequently, a gene fragment of KSH was cloned from Mycobacterium sp. NwIB-01, a sterol-transforming bacterium isolated from soil in our lab. According to the conservative sequence, the full-length 1188 bp gene encoding ksh (designated as M.S.-ksh) was obtained by chromosome walking, which showed 85% identity with the ksh of M. smegmatis mc(2)155. The heterologous expression of KSH was achieved in Escherichia coli BL21(DE3) using the pET-32a-c(+) vector system. The expressed KSH protein was mostly in soluble form after IPTG induction at 30 degreesC and accounted for more than 30% of total bacterial proteins according to SDS-PAGE electrophoresis. The molecular mass of KSH was about 45 kD, which was exactly the size predicted. After Ni2+ affinity chromatography, the purity of the target protein was more than 90%. Our work will definitely contribute to the industrial production of some steroid drugs by developing KSH genetically engineered bacteria.

Phase I enzyme induction in Girardinichthys viviparus, an endangered goodeid fish, exposed to water from native localities enriched with polychlorinated biphenyls

The present study examines the induction of mixed-function oxidase (MFO) enzymes, including CYP content CYP1A (EROD) activity and alcohol dehydrogenase activity (ADH), in an endemic Mexican fish species, the black-fin goodeid Girardinichthys viviparus, exposed to the water of two localities, Lake Texcoco (LTX) and Lake Zumpango, and to the same matrices enriched in polychlorinated biphenyls (PCBs) to simulate the potential toxic effects of sublethal increases in these xenobiotics. Fishes of both sexes born in the laboratory were exposed for 1, 2, 4, 8, and 16 days. Water from the two types of localities of the black-fin goodeid contains MFO inducers. Of the two, the most contaminated is LTX water, which also contains PCBs. EROD activity was higher in all treatments with female compared with male fish. This suggests greater metabolic compromise in female fish as a response to damage caused by these xenobiotics. In this species, CYP induction displayed two patterns that were not always concurrent with higher CYP1A activity. In the enriched matrix system, biotransformation processes were notably altered. Increased ADH may indicate that this enzyme is involved in the biotransformation of PCBs and their metabolites, particularly in male fish, and provides at least a part of reductive power required by the MFO enzymes; however, specific studies are needed to clarify this point.

Functional characterization of two novel CYP2C19 variants (CYP2C19*18andCYP2C19*19) found in a Japanese population

Cytochrome P450 2C19 (CYP2C19) plays an important role in the metabolism of a wide range of therapeutic drugs and exhibits genetic polymorphism with interindividual differences in metabolic activity. We have previously described two CYP2C19 allelic variants, namely CYP2C19*18 and CYP2C19*19 with Arg329His/Ile331Val and Ser51Gly/Ile331Val substitutions, respectively. In order to investigate precisely the effect of amino acid substitutions on CYP2C19 function, CYP2C19 proteins of the wild-type (CYP2C19.1B having Ile331Val) and variants (CYP2C19.18 and CYP2C19.19) were heterologously expressed in yeast cells, and their S-mephenytoin 4'-hydroxylation activities were determined. The K(m) value of CYP2C19.19 for S-mephenytoin 4'-hydroxylation was significantly higher (3.0-fold) than that of CYP2C19.1B. Although no significant differences in V(max) values on the basis of microsomal and functional CYP protein levels were observed between CYP2C19.1B and CYP2C19.19, the V(max)/K(m) values of CYP2C19.19 were significantly reduced to 29-47% of CYP2C19.1B. By contrast, the K(m), V(max) or V(max)/K(m) values of CYP2C19.18 were similar to those of CYP2C19.1B. These results suggest that Ser51Gly substitution in CYP2C19.19 decreases the affinity toward S-mephenytoin of CYP2C19 enzyme, and imply that the genetic polymorphism of CYP2C19*19 also causes variations in the clinical response to drugs metabolized by CYP2C19.

Expression of drug-metabolizing enzymes, nuclear transcription factors and ABC transporters in Caco-2 cells

1. Caco-2 cells are frequently used in intestinal drug absorption and metabolism studies, but little is known about the effects of drugs on the simultaneous expression of genes coding for drug-metabolizing enzymes (DMEs), nuclear transcription factors and ABC transporters. 2. The gene expression and enzyme activities of control and Aroclor 1254-treated cultures were therefore explored, the latter being a powerful inducer of DMEs. Fourteen- and 80-fold induction of CYP1A1 and CYP1A2 mRNA were shown, whereas expression of other DMEs was either increased (CYP2C8-2C19, 10-fold; CYP3A5, twofold; FMO1, 2 and 5, twofold; epoxide hydrolase, threefold) or repressed (CYP2D6 and CYP2E1 to 75% of control values). 3. Notably, gene copies of CYP3A4 and CYP2B6/7 were below the limit of detection, but a three- and 10-fold induction of HNF 1alpha + beta, HNF-4alpha4 and a similar 10-fold increase in STAT 3 and 4 was observed. 4. Similarly, c/EBP transcripts were only detected in treated cell cultures, but MRP1, its isoforms 3-5 as well as MDR-1 were increased threefold after dosing with Aroclor 1254. 5. Overall, CYP gene expression correlated well with the cognate enzyme activity using testosterone as a marker substrate.

Immunologically mediated toxicity

A major consideration which precedes the release of a new chemical into the environment of human beings is the possibility of its producing an undesirable or toxic effect. Toxicity is the clinical end-point of a mechanism which results in tissue damage. One such mechanism is mediated via the immunological system. The effect of some chemicals on immunologically competent cells has been to induce perturbations of immunological competence. This is currently under debate as a toxic hazard, and the concept is explored here, particularly in relation to the action of alkyl tins. Hypersensitivity, which is tissue damage resulting directly from an allergic reaction, depends on a substance acting as an antigen. Since many compounds of toxicological interest have a molecular weight less than 5000, the ability to induce an allergic state is governed in part by factors that influence antigen formation, covalent interactions with macromolecules and metabolism. These factors, together with an analysis of 'immunological specificity', are illustrated by experimental work on practolol, which demonstrates that an antibody present in human sera reacts with a product of first-phase metabolism.

Induction of drug-metabolizing enzymes by phenobarbitone: structural and biochemical aspects

Two aspects of the induction of microsomal monooxygenases by phenobarbitone have been investigated. First, structural associations between mitochondria and single cisternae of rough endoplasmic reticulum (mitochondria--RER complexes) may operate as functional units in the biosynthesis of cytochrome P-450. This was deduced from (i) studies on the subcellular distribution of the phenobarbitone-induced incorporation of leucine into microsomal proteins including apocytochromes P-450 and (ii) the incorporation of labelled delta-aminolaevulinic acid into the haem prosthetic group of cytochrome P-450. Secondly, in hepatocytes from chick embryo in primary monolayer culture, induction of cytochrome P-450-haemoproteins was markedly influenced by changes in the proliferative activity of hepatocytes. Inducibility of cytochrome P-450 by phenobarbitone and by beta-naphthoflavone was decreased in cultures with 'spontaneous' or experimentally increased proliferative activity of hepatocytes. Treatment with inhibitors of DNA synthesis increased the induction response.

Accumulation of flavonols in response to ultraviolet-B irradiation in soybean is related to induction of flavanone 3-beta-hydroxylase and flavonol synthase

There are several branch points in the flavonoid synthesis pathway starting from chalcone. Among them, the hydroxylation of flavanone is a key step leading to flavonol and anthocyanin. The flavanone 3-beta-hydroxylase (GmF3H) gene was cloned from soybean (Glycine max cultivar Sinpaldal) and shown to convert eriodictyol and naringenin into taxifolin and dihydrokaempferol, respectively. The major flavonoids in this soybean cultivar were found by LC-MS/MS to be kamepferol O-triglycosides and O-diglycosides. Expression of GmF3H and flavonol synthase (GmFLS) was induced by ultraviolet-B (UV-B) irradiation and their expression stimulated accumulation of kaempferol glycones. Thus, GmF3H and GmFLS appear to be key enzymes in the biosynthesis of the UV-protectant, kaempferol.

Protein engineering of toluene monooxygenases for synthesis of chiral sulfoxides

Enantiopure sulfoxides are valuable asymmetric starting materials and are important chiral auxiliaries in organic synthesis. Toluene monooxygenases (TMOs) have been shown previously to catalyze regioselective hydroxylation of substituted benzenes and phenols. Here we show that TMOs are also capable of performing enantioselective oxidation reactions of aromatic sulfides. Mutagenesis of position V106 in the alpha-hydroxylase subunit of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 and the analogous position I100 in toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 improved both rate and enantioselectivity. Variant TomA3 V106M of TOM oxidized methyl phenyl sulfide to the corresponding sulfoxide at a rate of 3.0 nmol/min/mg protein compared with 1.6 for the wild-type enzyme, and the enantiomeric excess (pro-S) increased from 51% for the wild type to 88% for this mutant. Similarly, T4MO variant TmoA I100G increased the wild-type oxidation rate by 1.7-fold, and the enantiomeric excess rose from 86% to 98% (pro-S). Both wild-type enzymes showed lower activity with methyl para-tolyl sulfide as a substrate, but the improvement in the activity and enantioselectivity of the mutants was more dramatic. For example, T4MO variant TmoA I100G oxidized methyl para-tolyl sulfide 11 times faster than the wild type did and changed the selectivity from 41% pro-R to 77% pro-S. A correlation between regioselectivity and enantioselectivity was shown for TMOs studied in this work. Using in silico homology modeling, it is shown that residue I100 in T4MO aids in steering the substrate into the active site at the end of the long entrance channel. It is further hypothesized that the main function of V106 in TOM is the proper positioning or docking of the substrate with respect to the diiron atoms. The results from this work suggest that when the substrate is not aligned correctly in the active site, the oxidation rate is decreased and enantioselectivity is impaired, resulting in products with both chiral configurations.

Regulation of CYP2A6 protein expression by skatole, indole, and testicular steroids in primary cultured pig hepatocytes

CYP2A6 is one of the enzymes involved in the hepatic metabolism of a naturally produced compound, skatole, in the pig. Low CYP2A6 activity has been linked to excessive accumulation of skatole in pig adipose tissue and development of the phenomenon "boar taint." CYP2A6 activity varies between male and female animals, suggesting the involvement of sex hormones in regulation of the enzyme activity and/or expression. The present study investigated whether pig hepatic CYP2A6 protein expression is regulated by the testicular steroids testosterone, androstenone, or estrone sulfate using primary cultured hepatocytes as a model system. The study has also examined whether CYP2A6 expression can be modulated by the boar taint compounds skatole and indole. The research has established that androstenone inhibits CYP2A6 protein expression at the concentration of 1, 10, and 100 nM by 55, 37, and 44%, respectively. In contrast to androstenone, skatole and indole (final concentrations, 1, 10, and 100 nM) had a stimulatory effect on CYP2A6 expression. The effect of indole was more pronounced than that of skatole (maximum induction by 145 and 70%, respectively). Estrone sulfate and testosterone did not have a significant effect on CYP2A6 protein level. This is, as far as we know, the first communication to report the regulation of pig hepatic CYP2A6 expression by steroids and boar taint compounds. The hormonal modulation of CYP2A6 expression might contribute to gender-related differences in pig hepatic CYP2A6 activity and skatole accumulation in pig adipose tissue.

Biodegradation of phenol at high initial concentration by Alcaligenes faecalis

Strain Alcaligenes faecalis was isolated and identified as a member of the genus Alcaligenes by using BIOLOG and 16S rDNA sequence analysis. The phenol biodegradation tests showed that the phenol-degrading potential of A. faecalis related greatly to the different physiological phases of inoculum. The maximum phenol degradation occurred at the late phase of the exponential growth stages, where 1600 mg L(-1) phenol was completely degraded within 76 h. A. faecalis secreted and accumulated a vast quantity of phenol hydroxylase in this physiological phase, which ensured that the cells could quickly utilize phenol as a sole carbon and energy source. In addition, the kinetic behavior of A. faecalis in batch cultures was also investigated over a wide range of initial phenol concentrations (0-1600 mg L(-1)) by using Haldane model. It was clear that the Haldane kinetic model adequately described the dynamic behavior of the phenol biodegradation by the strain of A. faecalis.

Salicylate and catechol levels are maintained in nahG transgenic poplar

Metabolic profiling was used to investigate the molecular phenotypes of a transgenic Populus tremula x P. alba hybrid expressing the nahG transgene, a bacterial gene encoding salicylate hydroxylase that converts salicylic acid to catechol. Despite the efficacy of this transgenic approach to reduce salicylic acid levels in other model systems and thereby elucidate roles for salicylic acid in plant signaling, transgenic poplars had similar foliar levels of salicylic acid and catechol to that of non-transformed controls and exhibited no morphological phenotypes. To gain a deeper understanding of the basis for these observations, we analyzed metabolic profiles of leaves as influenced by transgene expression. Expression of nahG decreased quinic acid conjugates and increased catechol glucoside, while exerting little effect on levels of salicylic acid and catechol, the substrate and product, respectively, of the nahG enzyme. This suggests a biological role of elevated constitutive salicylic acid levels in Populus, in contrast to other plant systems in which nahG dramatically reduces salicylic acid levels.

Human CYP2A6 Is Induced by Estrogen via Estrogen Receptor

Human CYP2A6, which is predominantly expressed in liver, is a key enzyme responsible for the metabolism of nicotine, coumarin, and some pharmaceutical drugs. CYP2A6 is also expressed in sex steroid-responsive tissues such as breast, ovary, uterus, testis, and adrenal grand. In this study, we examined the regulation of CYP2A6 gene by estrogen. Reverse transcription-polymerase chain reaction (RT-PCR) assays revealed that CYP2A6 mRNA was induced by estradiol in estrogen receptor (ER)-positive MCF-7 (2.9-fold) and HepG2 (1.3-fold) cells, but not in ER-negative MDA-MB-435 cells. Real-time RT-PCR assays revealed the CYP2A6 induction by estradiol in human hepatocytes (1.2- to 1.5-fold). Computer-assisted homology search identified a putative estrogen response element (ERE) at -2436 on the CYP2A6 gene. Electrophoretic mobility shift assays demonstrated specific binding of ERalpha to this element. Luciferase assays using MCF-7 cells revealed that the transcriptional activity of the CYP2A6 promoter was significantly activated by estradiol in an ERalpha-dependent manner, in which ERE was responsible for the activation. Chromatin immunoprecipitation assays verified the in vivo association of ERalpha with the ERE on the CYP2A6 gene. Immunohistochemical analyses using human endometrial tissues indicated that the CYP2A6 protein level in glandular cells was significantly higher in the proliferative phase than in the secretory phase, concomitant with local estrogen secretion during the menstrual cycle. These findings clearly demonstrated that CYP2A6 is directly induced by estrogen in an ERalpha-dependent manner, implying a biological role of CYP2A6 in estrogen-responsive tissues. Furthermore, this mechanism can also explain clinical aspects of increased nicotine metabolism under estrogen-rich environments.

Molecular cloning and functional expression of bovine deoxyhypusine hydroxylase cDNA and homologs

Deoxyhypusine hydroxylase is the second of the two enzymes that catalyzes the maturation of eukaryotic initiation factor 5A (eIF5A). The mature eIF5A is the only known protein in eukaryotic cells that contains the unusual amino acid hypusine (N(epsilon)-(4-amino-2(R)-hydroxybutyl)lysine). Synthesis of hypusine is essential for the function of eIF5A in eukaryotic cell proliferation and survival. Here, we describe the cloning and characterization of bovine deoxyhypusine hydroxylase cDNA and its homologs. The deduced bovine deoxyhypusine hydroxylase protein is 87% identical to human enzyme and 45% identical to yeast enzyme. The overexpressed enzyme showed activity in catalyzing the hydroxylation of the deoxyhypusine residue in the eIF5A intermediate. An amino acid substitution from Glu 57 to Gly located at one of the four conserved His-Glu (HE) pairs, the potential metal coordination sites, resulted in severe reduction of deoxyhypusine hydroxylase activity. A deletion at the HEAT-repeats 1-3 resulted in complete losses of deoxyhypusine hydroxylase activity.

Copper induction of lactate oxidase of Lactococcus lactis: a novel metal stress response

Lactococcus lactis IL1403, a lactic acid bacterium widely used for food fermentation, is often exposed to stress conditions. One such condition is exposure to copper, such as in cheese making in copper vats. Copper is an essential micronutrient in prokaryotes and eukaryotes but can be toxic if in excess. Thus, copper homeostatic mechanisms, consisting chiefly of copper transporters and their regulators, have evolved in all organisms to control cytoplasmic copper levels. Using proteomics to identify novel proteins involved in the response of L. lactis IL1403 to copper, cells were exposed to 200 muM copper sulfate for 45 min, followed by resolution of the cytoplasmic fraction by two-dimensional gel electrophoresis. One protein strongly induced by copper was LctO, which was shown to be a NAD-independent lactate oxidase. It catalyzed the conversion of lactate to pyruvate in vivo and in vitro. Copper, cadmium, and silver induced LctO, as shown by real-time quantitative PCR. A copper-regulatory element was identified in the 5' region of the lctO gene and shown to interact with the CopR regulator, encoded by the unlinked copRZA operon. Induction of LctO by copper represents a novel copper stress response, and we suggest that it serves in the scavenging of molecular oxygen.

Enhanced induction of cytochromes P450alk that oxidize methyl-ends of n-alkanes and fatty acids in the long-chain dicarboxylic acid-hyperproducing mutant of Candida maltosa

In the long-chain dicarboxylic acids (DCA)-hyperproducing mutant Candida maltosa strains, methyl-ends of n-alkanes and fatty acids are hydroxylated by n-alkane inducible cytochromes P450 (P450alk), presumably as an essential step in DCA production. A significantly higher production of P450alks was observed in response to n-alkane in the DCA-hyperproducing mutant strain M2030 than in the wild-type strain 1098. Northern analysis demonstrated that n-tetradecane induction levels of mRNAs of all four ALK genes encoding major P450alk isoforms involved in n-alkane assimilation were significantly higher in the DCA-hyperproducing mutant than in the wild-type strain. Among these four ALK genes, enhancement of the transcriptional induction level of ALK5, which prefers fatty acids as substrates, was prominent in the mutant. In agreement with Northern analysis, promoters of ALK genes, especially that of ALK5, more strongly responded to n-alkanes in the DCA-hyperproducing mutant than in the wild-type strain. These results suggest that the transcriptional control of ALK genes in the DCA-hyperproducing mutant strains was altered preferably to accelerate DCA production.

Development of a fed-batch process for the production of the cytochrome P450 monooxygenase CYP102A1 from Bacillus megaterium in E. coli

A fed-batch process utilizing a pET-based expression system (pET28a+ derivative) and E. coli BL21(DE3) as production strain for the heterologous expression of recombinant cytochrome P450 monooxygenase CYP102A1 from Bacillus megaterium was developed. In a first step the expression was optimized during a series of flask experiments testing several parameters for their influence on the expression level, activity and solubility of the recombinant protein. The optimal process parameters found in the flask experiments were transferred to a cultivation process in a 5l (operating volume) bioreactor with a special focus on the feeding strategy and the aeration during expression. Glycerol feeding proved to be superior over glucose as carbon source since the formation of larger amounts of acetate was prevented. Expression levels exceeding 12,500nmoll(-1), corresponding to approximately 1.5gl(-1) of product in culture medium ( approximately 11% of CDW) could be demonstrated. The P450 enzyme showed high activity and high solubility. The findings now can be transferred to other enzyme variants and different P450 monooxygenases to increase production of recombinant proteins.

Multiple levels of control of the expression of the human A beta H-J-J locus encoding aspartyl-beta-hydroxylase, junctin, and junctate

The human AbetaH-J-J locus is a genomic sequence which generates three functionally distinct proteins, the enzyme aspartyl-beta-hydroxylase (AbetaH), the structural protein of sarcoplasmic reticulum junctin, and the membrane-bound calcium binding protein junctate. The first and second exons are mutually exclusive when mature mRNAs are produced. Moreover, the use of different splice donors has been shown to be involved in the generation of protein diversity by alternative splicing. As to transcriptional regulation, two promoters (P1 and P2) were identified. When the P1 and P2 promoter sequences are compared, important differences are clearly detectable. The most interesting result emerging from studies focused on the P2 promoter is that the calcium-dependent transcriptional factor MEF-2 activates the transcription of junctin, junctate, and AbetaH in excitable tissues and, to a lesser extent, in kidney. No Sp1 binding sites are present in the P2 promoter. In contrast, P1 promoter contains GC-rich sequences, which have homologies with the Sp1 consensus binding site.

Fatty acid 2-hydroxylase, encoded by FA2H, accounts for differentiation-associated increase in 2-OH ceramides during keratinocyte differentiation

Ceramides in mammalian stratum corneum comprise a heterogeneous mixture of molecular species that subserve the epidermal permeability barrier, an essential function for survival in a terrestrial environment. In addition to a variation of sphingol species, hydroxylation of the amide-linked fatty acids contributes to the diversity of epidermal ceramides. Fatty acid 2-hydroxylase, encoded by the gene FA2H, the mammalian homologue of FAH1 in yeast, catalyzes the synthesis of 2-hydroxy fatty acid-containing sphingolipids. We assessed here whether FA2H accounts for 2-hydroxyceramide/2-hydroxyglucosylceramide synthesis in epidermis. Reverse transcription-PCR and Western immunoblots demonstrated that FA2H is expressed in cultured human keratinocytes and human epidermis, with FA2H expression and fatty acid 2-hydroxylase activity increased with differentiation. FA2H-siRNA suppressed 2-hydroxylase activity and decreased 2-hydroxyceramide/2-hydroxyglucosylceramide levels, demonstrating that FA2H accounts for synthesis of these sphingolipids in keratinocytes. Whereas FA2H expression and 2-hydroxy free fatty acid production increased early in keratinocyte differentiation, production of 2-hydroxyceramides/2-hydroxyglucosylceramides with longer chain amide-linked fatty acids (> or =C24) increased later. Keratinocytes transduced with FA2H-siRNA contained abnormal epidermal lamellar bodies and did not form the normal extracellular lamellar membranes required for the epidermal permeability barrier. These results reveal that 1) differentiation-dependent up-regulation of ceramide synthesis and fatty acid elongation is accompanied by up-regulation of FA2H; 2) 2-hydroxylation of fatty acid by FA2H occurs prior to generation of ceramides/glucosylceramides; and 3) 2-hydroxyceramides/2-hydroxyglucosylceramides are required for epidermal lamellar membrane formation. Thus, late differentiation-linked increases in FA2H expression are essential for epidermal permeability barrier homeostasis.

Optimization of fermentation conditions for P450 BM-3 monooxygenase production by hybrid design methodology

Factorial design and response surface techniques were used to design and optimize increasing P450 BM-3 expression in E. coli. Operational conditions for maximum production were determined with twelve parameters under consideration: the concentration of FeCl(3), induction at OD(578) (optical density measured at 578 nm), induction time and inoculum concentration. Initially, Plackett-Burman (PB) design was used to evaluate the process variables relevant in relation to P450 BM-3 production. Four statistically significant parameters for response were selected and utilized in order to optimize the process. With the 416C model of hybrid design, response surfaces were generated, and P450 BM-3 production was improved to 57.90x10(-3) U/ml by the best combinations of the physicochemical parameters at optimum levels of 0.12 mg/L FeCl(3), inoculum concentration of 2.10%, induction at OD(578) equal to 1.07, and with 6.05 h of induction.

Large scale production of the copper enzyme peptidylglycine monooxygenase using an automated bioreactor

Rat PHM (peptidylglycine alpha-hydroxylating monooxygenase; EC 1.14.17.3) expressed in CHO DG44 cells as a recombinant protein (rat PHMcc, residues 42-356 cloned in the pCIS vector, A.S. Kolhekar, H.T. Keutman, R. E. Mains, A.S.W. Quon, B.A. Eipper, Biochemistry 36 (1997) 10901-10909), was produced in two different bioreactors, a Cellmax 100 (B1) and an Accusyst-MiniMax (B2). B2 contains features not present in B1, which contribute to environmental control, and ease of operation, and was more successful at producing high quality PHM than B1 in both yield (B1: 5mg/day, B2: 12-15 mg/day), activity (B1: 12-20 micromol O(2)/min/mg, B2: 24-36 micromol O(2)/min/mg), and viability (B1: <6 months, B2: indefinite). Additionally, B1 exhibited clipping at Ser 61, and a decline in quality late in the run. PHM from B2 was of consistent quality and homogeneity throughout the run. The increased yield and purity made possible collection of visible spectra of the Cu(II) sites, and mass spectrometric data not previously available.