Search results for "Operon"

Generation and characterization of tTS-H4: a novel transcriptional repressor that is compatible with the reverse tetracycline-controlled TET-ON system

2007

Background Conditional gene regulatory systems ensuring tight and adjustable expression of therapeutic genes are central for developing future gene therapy strategies. Among various regulatory systems, tetracycline-controlled gene expression has emerged as a safe and reliable option. Moreover, the tightness of tetracycline-regulated gene switches can be substantially improved by complementing transcriptional activators with antagonizing repressors. Methods To develop novel tetracycline-responsive transcriptional repressors, we fused various transcriptional silencing domains to the TetR (B/E) DNA-binding and dimerization domain of the Tn10-encoded tetracycline resistance operon (TetR (B/E)).…

Two master switch regulators trigger A40926 biosynthesis in Nonomuraea sp. strain ATCC 39727

2015

ABSTRACT The actinomycete Nonomuraea sp. strain ATCC 39727 produces the glycopeptide A40926, the precursor of dalbavancin. Biosynthesis of A40926 is encoded by the dbv gene cluster, which contains 37 protein-coding sequences that participate in antibiotic biosynthesis, regulation, immunity, and export. In addition to the positive regulatory protein Dbv4, the A40926-biosynthetic gene cluster encodes two additional putative regulators, Dbv3 and Dbv6. Independent mutations in these genes, combined with bioassays and liquid chromatography-mass spectrometry (LC-MS) analyses, demonstrated that Dbv3 and Dbv4 are both required for antibiotic production, while inactivation of dbv6 had no effect. In …

Capillary enlargement, not sprouting angiogenesis, determines beneficial therapeutic effects and side effects of angiogenic gene therapy.

2010

Aims Currently, it is still unclear which mechanisms drive metabolic benefits after angiogenic gene therapy. The side-effect profile of efficient angiogenic gene therapy is also currently incompletely understood. In this study, the effects of increasing doses of adenoviral (Ad) vascular endothelial growth factor-A (VEGF-A) were evaluated on vascular growth, metabolic benefits, and systemic side effects. Methods and results Adenoviral vascular endothelial growth factor-A or AdLacZ control was injected intramuscularly (109–1011 vp/mL) or intra-arterially (5 × 1011 vp/mL) into rabbit ( n = 102) hindlimb muscles and examined 6 or 14 days later. Blood flow, tissue oedema, metabolic benefits, and…

Harvesting canthinones: identification of the optimal seasonal point of harvest of Zanthoxylum chiloperone leaves as a source of 5-methoxycanthin-6-o…

2015

This article is focused on the seasonal variation in the contents of 5-methoxycanthin-6-one from the leaves of Zanthoxylum chiloperone (Rutaceae). Based on the pharmacological interest presented by 5-methoxycanthin-6-one, its seasonal variation in Z. chiloperone leaves was analysed in order to determine the best time for harvesting, optimising the 5-methoxycanthin-6-one content. The seasonal dynamics of canthinone alkaloids can be the key to improve the isolation from natural sustainable sources, such as leaves. Complementarily, this study describes the phytochemistry of leaf from this Ruraceae species.

Calcium signaling in plant defense: involvement of subcellular compartments and glutamate receptorsCalcium signaling in plant defense: involvement of…

2012

Distinct 5' SCL enhancers direct transcription to developing brain, spinal cord, and endothelium: neural expression is mediated by GATA factor bindin…

1999

The SCL gene encodes a basic helix-loop-helix transcription factor with a pivotal role in the development of endothelium and of all hematopoietic lineages. SCL is also expressed in the central nervous system, although its expression pattern has not been examined in detail and its function in neural development is unknown. In this article we present the first analysis of SCL transcriptional regulation in vivo. We have identified three spatially distinct regulatory modules, each of which was both necessary and sufficient to direct reporter gene expression in vivo to three different regions within the normal SCL expression domain, namely, developing endothelium, midbrain, and hindbrain/spinal …

The L-tartrate/succinate antiporter TtdT (YgjE) of L-tartrate fermentation in Escherichia coli.

2007

ABSTRACT Escherichia coli ferments l -tartrate under anaerobic conditions in the presence of an additional electron donor to succinate. The carrier for l -tartrate uptake and succinate export and its relation to the general C 4 -dicarboxylate carriers DcuA, DcuB, and DcuC were studied. The secondary carrier TtdT, encoded by the ttdT (previously called ygjE ) gene, is required for the uptake of l -tartrate. The ttdT gene is located downstream of the ttdA and ttdB genes, encoding the l -tartrate dehydratase TtdAB. Analysis of mRNA by reverse transcription-PCR showed that ttdA , ttdB , and ttdT are cotranscribed. Deletion of ttdT abolished growth by l -tartrate and degradation of l -tartrate c…

Production of soluble eukaryotic recombinant proteins in E. coli is favoured in early log-phase cultures induced at low temperature

2013

Abstract Background Producing recombinant plant proteins expressed in Escherichia coli produce in high yields and in a soluble and functional form can be difficult. Under overexpression conditions, proteins frequently accumulate as insoluble aggregates (inclusion bodies) within the producing bacteria. We evaluated how the initial culture density, temperature and duration of the expression stage affect the production of some eukaryotic enzymes in E. coli. Findings A high yield of active soluble proteins was obtained by combining early-log phase cultures and low temperatures for protein induction. When IPTG was added at OD600 = 0.1 and cultures were maintained at 4°C for 48-72 h, the soluble …

Staphylococcal NreB: an O2-sensing histidine protein kinase with an O2-labile iron-sulphur cluster of the FNR type

2004

Summary The nreABC ( n itrogen re gulation) operon encodes a new staphylococcal two-component regulatory sys- tem that controls dissimilatory nitrate/nitrite reduc- tion in response to oxygen. Unlike other two- component sensors NreB is a cytosolic protein with four N-terminal cysteine residues. It was shown that both the NreB-cysteine cluster and Fe ions are required for function. Isolated NreB was converted to the active form by incubation with cysteine desul- phurase, ferrous ions and cysteine. This activation is typical for FeS-containing proteins and was reversed by oxygen. During reconstitution an absorption band at 420 nm and a yellow-brownish colour (typical for an FNR-type iron-sul…

Blueprint for a minimal photoautotrophic cell: conserved and variable genes in Synechococcus elongatus PCC 7942.

2011

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.-- et al.