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Cyclase Gene (cyclase + gene)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

ABA activates ADPR cyclase and cADPR induces a subset of ABA-responsive genes in Arabidopsis

THE PLANT JOURNAL, Issue 3 2004
Juan-Pablo Sánchez
Summary Cyclic ADP-ribose (cADPR) was previously shown to activate transient expression of two abscisic acid (ABA)-responsive genes in tomato cells. Here, we show that the activity of the enzyme responsible for cADPR synthesis, ADP-ribosyl (ADPR) cyclase, is rapidly induced by ABA in both wild-type (WT) and abi1-1 mutant Arabidopsis plants in the absence of protein synthesis. Furthermore, in transgenic Arabidopsis plants, induced expression of the Aplysia ADPR cyclase gene resulted in an increase in ADPR cyclase activity and cADPR levels, as well as elevated expression of ABA-responsive genes KIN2, RD22, RD29a, and COR47 (although to a lesser extent than after ABA induction). Genome-wide profiling indicated that about 28% of all ABA-responsive genes in Arabidopsis are similarly up- and downregulated by cADPR and contributed to the identification of new ABA-responsive genes. Our results suggest that activation of ADPR cyclase is an early ABA-signaling event partially insensitive to the abi1-1 mutation and that an increase in cADPR plays an important role in downstream molecular and physiological ABA responses. [source]

Biosynthesis of the Vitamin E Compound ,-Tocotrienol in Recombinant Escherichia coli Cells

CHEMBIOCHEM, Issue 15 2008
Christoph Albermann Dr.
Abstract The biosynthesis of natural products in a fast growing and easy to manipulate heterologous host system, such as Escherichia coli, is of increasing interest in biotechnology. This procedure allows the investigation of complex natural product biosynthesis and facilitates the engineering of pathways. Here we describe the cloning and the heterologous expression of tocochromanol (vitamin E) biosynthesis genes in E. coli. Tocochromanols are synthesized solely in photosynthetic organisms (cyanobacteria, algae, and higher green plants). For recombinant tocochromanol biosynthesis, the genes encoding hydroxyphenylpyruvate dioxygenase (hpd), geranylgeranylpyrophosphate synthase (crtE), geranylgeranylpyrophosphate reductase (ggh), homogentisate phytyltransferase (hpt), and tocopherol-cyclase (cyc) were cloned in a stepwise fashion and expressed in E. coli. Recombinant E. coli cells were cultivated and analyzed for tocochromanol compounds and their biosynthesis precursors. The expression of only hpd from Pseudomonas putida or crtE from Pantoea ananatis resulted in the accumulation of 336 mgL,1 homogentisate and 84 ,gL,1 geranylgeranylpyrophosphate in E. coli cultures. Simultaneous expression of hpd, crtE, and hpt from Synechocystis sp. under the control of single tac-promoter resulted in the production of methyl-6-geranylgeranyl-benzoquinol (67.9 ,g,g,1). Additional expression of the tocopherol cyclase gene vte1 from Arabidopsis thaliana resulted in the novel formation of a vitamin E compound,,-tocotrienol (15 ,g,g,1),in E. coli. [source]

Adenylyl cyclase Rv0386 from Mycobacterium tuberculosis H37Rv uses a novel mode for substrate selection

FEBS JOURNAL, Issue 12 2005
Lucila I. Castro
Class III adenylyl cyclases usually possess six highly conserved catalytic residues. Deviations in these canonical amino acids are observed in several putative adenylyl cyclase genes as apparent in several bacterial genomes. This suggests that a variety of catalytic mechanisms may actually exist. The gene Rv0386 from Mycobacterium tuberculosis codes for an adenylyl cyclase catalytic domain fused to an AAA-ATPase and a helix-turn-helix DNA-binding domain. In Rv0386, the standard substrate, adenine-defining lysine-aspartate couple is replaced by glutamine-asparagine. The recombinant adenylyl cyclase domain was active with a Vmax of 8 nmol cAMP·mg,1·min,1. Unusual for adenylyl cyclases, Rv0386 displayed 20% guanylyl cyclase side-activity with GTP as a substrate. Mutation of the glutamine-asparagine pair either to alanine residues or to the canonical lysine-aspartate consensus abolished activity. This argues for a novel mechanism of substrate selection which depends on two noncanonical residues. Data from individual and coordinated point mutations suggest a model for purine definition based on an amide switch related to that previously identified in cyclic nucleotide phosphodiesterases. [source]

Targeted genomic detection of biosynthetic pathways: anaerobic production of hopanoid biomarkers by a common sedimentary microbe

GEOBIOLOGY, Issue 1 2005
W. W. FISCHER
ABSTRACT The lipid biomarker principle requires that preservable molecules (molecular fossils) carry specific taxonomic, metabolic, or environmental information. Historically, an empirical approach was used to link specific taxa with the compounds they produce. The lipids extracted from numerous, but randomly cultured species provided the basis for the interpretation of biomarkers in both modern environments and in the geological record. Now, with the rapid sequencing of hundreds of microbial genomes, a more focused genomic approach can be taken to test phylogenetic patterns and hypotheses about the origins of biomarkers. Candidate organisms can be selected for study on the basis of genes that encode proteins fundamental to the synthesis of biomarker compounds. Hopanoids, a class of pentacyclic triterpenoid lipid biomarkers, provide an illustrative example. For many years, interpretations of biomarker data were made with the assumption that hopanoids are produced only by aerobic organisms. However, the recent discovery of 13C-depleted hopanoids in environments undergoing anaerobic methane oxidation and in enrichment cultures of anammox planctomycetes indicates that some hopanoids are produced anaerobically. To further examine the potential distribution of hopanoid biosynthesis by anaerobes, we searched publicly available genomic databases for the presence of squalene-hopene cyclase genes in known obligate or facultative anaerobes. Here we present evidence that Geobacter sulfurreducens, Geobacter metallireducens, and Magnetospirillum magnetotacticum, all bacteria common in anoxic environments, have the appropriate genes for hopanoid biosynthesis. We further show that these data accurately predict that G. sulfurreducens does produce a variety of complex hopanoids under strictly anaerobic conditions in pure culture. [source]

Elucidation of Oxygenation Steps during Oviedomycin Biosynthesis and Generation of Derivatives with Increased Antitumor Activity

CHEMBIOCHEM, Issue 2 2009
Felipe Lombó Dr.
Abstract Eight different angucyclinones have been produced in Streptomyces albus by combining three oxygenase genes together with the polyketide synthase and cyclases genes from the oviedomycin biosynthetic gene cluster from Streptomyces antibioticus ATCC 11891. Four of these compounds were fully characterized for the first time. Three of these angucyclinones,prejadomycin-2-carboxylate (2), 4a,12b-dehydro-UWM6 (5), and prejadomycin (3),show a significant increase in their in vitro antitumor activity relative to oviedomycin (1). A hypothesis for the sequence of tailoring events catalyzed by these three oxygenases during oviedomycin biosynthesis is proposed. In this hypothesis OvmOII acts as a bifunctional oxygenase/dehydratase. [source]