cblB defect is a rare type of methylmalonic aciduria. In this study, a Chinese boy was diagnosed with methylmalonic aciduria cblB type and a novel mutation in the MMAB gene. The clinical presentations, blood acylcarnitines profiles, urine organic acids and genetic features of the patient were reported. The boy presented with fever, feeding difficulty and lethargy at the age of 2 months. Seven days later, he had coma, cold limb, thrombocytopenia, metabolic acidosis and liver damage. His blood propionylcarnitine and urinary methylmalonic acid levels increased significantly, but the plasma total homocysteine level was in the normal range, which supported the diagnosis of isolated methylmalonic aciduria. Gene analysis was performed by direct sequencing. No mutation in the MUT gene was found. However, a reported mutation c.577G>A (p.E193K) and a novel mutation c.562G>A (p.V188M) in the MMAB gene were identified, which confirmed the diagnosis of methylmalonic aciduria cblB type. Progressive clinical and biochemical improvement has been observed after hydroxylcobalamin injection, protein-restricted diet with the supplements of special formula and L-carnitine. He is currently 3 years and 11 months old and has a normal development condition. The phenotypes of the patients with cblB defect are nonspecific. Metabolic analysis and MMAB gene analysis are keys for the diagnosis of the disorder.
Alkyl and Aryl Transferases ; genetics ; Amino Acid Metabolism, Inborn Errors ; genetics ; Humans ; Infant ; Male ; Mutation

Diterpenes, an important class of natural compounds, are widely distributed in nature. As the valuable diterpenoids continue to be found, diterpene synthase in the course of diterpene synthesis get as much attention as possible. The multiformity of end-product-diterpenoids were also due to the diversity of diterpene synthase. This paper focuses on the advances in recent biosynthesis pathway of diterpene and types, cloning, catalytic mechanism, synthetic biology application.
Alkyl and Aryl Transferases ; metabolism ; Biosynthetic Pathways ; Diterpenes ; metabolism ; Isomerases ; metabolism ; Phosphorus-Oxygen Lyases ; metabolism ; Plant Proteins ; metabolism

To construct an engineered Saccharomyces cerevisiae producing high titres of amorpha-4,11-diene, we investigated the possible synergistic effect of different vectors containing amorpha-4,11-diene synthase(ADS) gene within one yeast cell. We constructed the ADS recombinant plasmid pGADADS. This plasmid and another ADS recombinant plasmid pYeDP60/G/ADS were alone, or co-transformed into yeast Saccharomyces cerevisiae W303-1B and WK1, respectively, resulting in the following engineered yeasts, W303B[pGADADS], W303B[pYGADS], W303B[pYGADS+pGADADS], WK1[pGADADS], WK1[pYGADS] and WK1[pYGADS+pGADADS]. All of the six strains were cultured for GC-MS analysis of amorpha-4,11-diene. The results showed that all of the engineered yeasts could produce amorpha-4,11-diene. The yield of the product was improved with increasing ADS gene copies while no deleterious effect on the strain growth was found. Moreover, the product yield of the engineered yeast co-transformed with multiple plasmids was much higher than the total yield of the different engineered yeasts with only one plasmid, respectively. In conclusion, there was a distinct synergistic effect between different recombinant ADS plasmids within one cell. Our results facilitate the construction of the engineered yeast with high yield of amorpha-4,11-diene, the precursor of artemisinin.
Alkyl and Aryl Transferases ; biosynthesis ; genetics ; Artemisinins ; chemistry ; metabolism ; Genetic Engineering ; methods ; Genetic Vectors ; genetics ; Recombination, Genetic ; Saccharomyces cerevisiae ; genetics ; metabolism

Artemisinin-based combination therapies (ACTs) are recommended to be the most effective therapies for the first-line treatment of uncomplicated falciparum malaria. However, artemisinin is often in short supply and unaffordable to most malaria patients, which limits the wide use of ACTs. Production of amorpha-4,11-diene, an artemisinin precursor, was investigated by engineering a heterologous isoprenoid biosynthetic pathway in Escherichia coli. The production of amorpha-4,11-diene was achieved by expression of a synthetic amorpha-4,11-diene synthase gene in Escherichia coli DHGT7 and further improved by about 13.3 fold through introducing the mevalonate pathway from Enterococcus faecalis. After eliminating three pathway bottlenecks including amorpha-4,11-diene synthase, HMG-CoA reducase and mevalonate kinase by optimizing the metabolic flux, the yield of amorpha-4,11-diene was increased by nearly 7.2 fold and reached at 235 mg/L in shaking flask culture. In conclusion, an engineered Escherichia coli was constructed for high-level production of amorpha-4,11-diene.
Alkyl and Aryl Transferases ; genetics ; Antimalarials ; metabolism ; Artemisinins ; metabolism ; Enterococcus faecalis ; genetics ; Escherichia coli ; genetics ; metabolism ; Metabolic Engineering ; methods ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; Sesquiterpenes ; metabolism ; Transformation, Bacterial

Artemisinin, a new and a very potent antimalarial drug, is produced by the Chinese medicinal herb Artemisia annua L. It is a sesquiterpene lactone with an endoperoxide bridge and is active against chloroquine resistant forms of Plasmodium falciparum. The relatively low yield (0.01% - 0.6%) of artemisinin in A. annua is a serious limitation to the commercialization of the drug. Therefore, a through understanding of the biosynthetic pathway and the characterization of the involved enzymes are important for the biology production of artemisinin. This review is focused on the recent progress in the molecular regulation of artemisinin biosynthesis from the following aspects: the biosynthetic pathway of artemisinin, the key enzymes involved in artemisinin biosynthesis, and the molecular regulation of artemisinin biosynthesis. The biosynthetic pathway of artemisinin belongs to the isoprenoid metabolite pathway, the key enzymes involved in the biosynthesis of artemisinin include: 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), farnesyl diphosphate synthase (FDPS), and amorpha-4, 11-diene synthase, of which amorpha-4, 11-diene synthase catalyzes the cyclisation of the ubiquitous precursor farnesyl diphosphate to the highly specific olefinic sesquiter-pene skeletons and has been postulated as the regulatory step in the biosynthesis of artemisinin. Recently the gene encoding of the amorpha-4, 11-diene synthase has been cloned and the functional expressions have been studied by several research teams, therefore, the breakthroughs in production of artemisinin could hopefully be achieved by metabolic engineering of the plant, in particular, by over-expressing enzyme(s) catalyzing the rate limiting step(s) of artemisinin biosynthesis or by inhibiting the enzyme(s) of other pathway competing for its precursors. Besides, the effects of the heterogenesis isoprenoid pathway related genes on artemisinin biosynthesis of the transformed plants were also discussed.
Alkyl and Aryl Transferases ; genetics ; metabolism ; Antimalarials ; metabolism ; Artemisia annua ; enzymology ; genetics ; metabolism ; Artemisinins ; metabolism ; Biotechnology ; methods ; Models, Biological ; Signal Transduction ; genetics ; physiology

Sclareol is a member of labdane type diterpenes mostly used as fragrance ingredient. To enable microbial production of sclareol, synthetic pathways were constructed by incorporating labdenediol diphosphate synthase (LPPS) and terpene synthase (TPS) of the plant Salvia sclarea into Saccharomyces cerevisiae. It was found that sclareol production could be benefited by overexpression of key enzyme for precursor biosynthesis, construction of fusion protein for substrate channeling, and removal of signal peptides from LPPS and TPS. Under optimal shake flask culture conditions, strain S6 produced 8.96 mg/L sclareol. These results provided useful information for development of heterologous hosts for production of terpenoids.
Alkyl and Aryl Transferases ; biosynthesis ; genetics ; Diterpenes ; metabolism ; Metabolic Engineering ; methods ; Metabolic Networks and Pathways ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Saccharomyces cerevisiae ; genetics ; metabolism ; Salvia ; chemistry ; enzymology ; genetics

OBJECTIVETo try to find the ways to enhance the expression of ADS gene encoding amorpha-4,11-diene synthase, a key enzyme in artemisinin biosynthesis pathway catalyzing the formation of amorpha-4,11-diene from farnesyl diphosphate, and accelerate the artemisinin synthesis, the promoter of ADS was isolated and characterized.

METHOD5' untranslated regions of ADS were isolated from Artemisia annua with PCR. For functional characterization, the isolated fragment was fused with GUS reporter gene and introduced into Nicotiana tabacum by Agrobacterium-mediated transformation. The GUS expression regulated by 5' untranslated regions of ADS in transgenic N. tabacum under the normal or stressed conditions were detected by histochemical staining and quantitative spectrophotometry assay.

RESULTThe 2 448 bp DNA fragment upstream of ADS coding sequence was isolated from A. annua and introduced into N. tabacum. Histochemical staining showed that the isolated fragment conferred stable GUS expression in transgenic plants. The quantitative results showed that the GUS activity in transgenic tobacco plants treated by low-temperature (4 degrees C) and ultraviolet irradiation were 1. 6 and 2.2 folds higher than that in the controls.

CONCLUSIONIt was suggested that the isolated fragment had promoter activity and maybe responsive to adverse environmental stresses.

5' Untranslated Regions ; genetics ; Alkyl and Aryl Transferases ; genetics ; metabolism ; Artemisia annua ; enzymology ; genetics ; Gene Expression Regulation, Plant ; Genetic Vectors ; genetics ; Molecular Sequence Data ; Promoter Regions, Genetic ; genetics

A sesquiterpene synthase (AsSS4) full-length open reading frame (ORF) cDNA was cloned from wounded stems of Aquilaria sinensis by RT-PCR method. The result showed that the ORF of AsSS4 was 1,698 bp encoding 565 amino acids. Prokaryotic expression vector pET28a-AsSS4 was constructed and transformed into E. coli BL21 (DE3) pLysS. Recombinant AsSS4 protein was obtained after induction by IPTG and SDS-PAGE analysis with a MW of 64 kD. Enzymatic reactions using farnesyl pyrophosphate showed that recombinant AsSS4 protein purified by Ni-agarose gel yielded five sesquiterpene compounds, cyclohexane, 1-ethenyl-1-methyl-2, 4-bis(1-methylethenyl)-, β-elemene, α-guaiene, α-caryophyllene and δ-guaiene. This paper reported the first cloning and functional characterization of AsSS4 gene from A. sinensis, which will establish a foundation for future studies on the molecular mechanisms of wound-induce agarwood formation in A. sinensis
Alkyl and Aryl Transferases ; biosynthesis ; genetics ; Azulenes ; Cloning, Molecular ; DNA, Complementary ; Escherichia coli ; Open Reading Frames ; Polyisoprenyl Phosphates ; Recombinant Proteins ; biosynthesis ; Sesquiterpenes ; metabolism ; Sesquiterpenes, Guaiane ; Thymelaeaceae ; enzymology ; genetics

Amorpha-4,11-diene synthase (ADS) can convert farnesyl pyrophosphate (FPP) to amorpha-4, 11-diene, a precursor of artemisinin. ADS plays an important role in the biosynthesis of artemisinin. This review summarizes the molecular biology and metabolic engineering study of ADS in recent years. The genomic DNA and its cDNA sequences of amorpha-4, 11-diene synthase were cloned from Artemisia annua L. The cDNA encoding amorpha-4, 11-diene synthase contains a 1 641 bp open reading frame coding for 546 amino acids. ADS shows a broad pH optimum and an absolute requirement for divalent metal ions as cofactors. The specificity of ADS to the substrates and products is not high and the formation of amorpha-4, 11-diene by ADS from FPP is achieved by an initial 1, 6-closure with subsequent 1, 10-closure. The ADS cDNA cloned from Artemisia annua L, or totally synthesized by PCR, was introduced into different hosts including E. coli, S. cerevisiae, Nicotiana tabacum L. Arabidopsis thaliana and A. nidulans resulting in varied engineering microorganisms and cells producing amorpha-4, 11-diene. The way to improve the production of amorpha-4, 11-diene was investigated by two strategies such as improving the supply of substrate and directing FPP flux to amorpha-4, 11-diene production from competing pathways.
Alkyl and Aryl Transferases ; biosynthesis ; genetics ; Amino Acid Sequence ; Antimalarials ; metabolism ; Arabidopsis ; enzymology ; genetics ; Artemisia annua ; enzymology ; genetics ; Artemisinins ; metabolism ; Aspergillus ; genetics ; metabolism ; Cloning, Molecular ; DNA, Complementary ; genetics ; Escherichia coli ; genetics ; metabolism ; Metabolic Engineering ; Saccharomyces cerevisiae ; genetics ; metabolism ; Tobacco ; enzymology ; genetics

OBJECTIVETo evaluate the expression of COX10 mRNA in the testes of non-obstructive azoospermia patients and normal men.

METHODSA cDNA microarray containing COX10 and some other genes as RBM and EIF1AY was used to identify the differential gene expression profiles in the normal and azoospermic testes. The cDNA probes were prepared by labeling mRNA from azoospermic and normal testis tissues with Cy5-dUTP and Cy3-dUTP respectively through reverse transcription. The mixed cDNA probes were then hybridized with cDNA microarray. Later the fluorescent signals were scanned and the values of Cy5-dUTP and Cy3-dUTP on each spot were calculated and analyzed. After that an ISH was employed to detect the expression of COX10 mRNA in 10 fertile and 39 non-obstructive azoospermic testes, and the expression levels were compared to evaluate the significance.

RESULTSWe obtained 128 differentially expressed genes that might be related with azoospermia, among which 56 were up-regulated and 72 down-regulated, with the expression of COX10 significantly decreased. In situ hybridization confirmed that the mRNA expression of COX10 was stronger in the spermatogenic cells of the normal fertile than the azoospermic testes.

CONCLUSIONCOX10 may play a certain role in the development and progression of azoospermia. The technique of cDNA microarray can be applied to further studies of screening non-obstructive azoospermia associated genes.

Alkyl and Aryl Transferases ; genetics ; metabolism ; Azoospermia ; genetics ; metabolism ; Electron Transport Complex IV ; Gene Expression Profiling ; Humans ; In Situ Hybridization ; Male ; Membrane Proteins ; genetics ; metabolism ; Oligonucleotide Array Sequence Analysis ; Testis ; metabolism