scholarly journals Fungal Gene Expression on Demand: an Inducible, Tunable, and Metabolism-Independent Expression System for Aspergillus niger

2011 ◽  
Vol 77 (9) ◽  
pp. 2975-2983 ◽  
Author(s):  
Vera Meyer ◽  
Franziska Wanka ◽  
Janneke van Gent ◽  
Mark Arentshorst ◽  
Cees A. M. J. J. van den Hondel ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Expression System ◽  
Constitutive Expression ◽  
Plant Diseases ◽  
Fine Tuning ◽  
Gene Copy ◽  
Limited Information ◽  
Genomic Locus ◽  
Expression Levels ◽  
Fungal Genes

ABSTRACTFilamentous fungi are the cause of serious human and plant diseases but are also exploited in biotechnology as production platforms. Comparative genomics has documented their genetic diversity, and functional genomics and systems biology approaches are under way to understand the functions and interaction of fungal genes and proteins. In these approaches, gene functions are usually inferred from deletion or overexpression mutants. However, studies at these extreme points give only limited information. Moreover, many overexpression studies use metabolism-dependent promoters, often causing pleiotropic effects and thus limitations in their significance. We therefore established and systematically evaluated a tunable expression system forAspergillus nigerthat is independent of carbon and nitrogen metabolism and silent under noninduced conditions. The system consists of two expression modules jointly targeted to a defined genomic locus. One module ensures constitutive expression of the tetracycline-dependent transactivator rtTA2S-M2, and one module harbors the rtTA2S-M2-dependent promoter that controls expression of the gene of interest (the Tet-on system). We show here that the system is tight, responds within minutes after inducer addition, and allows fine-tuning based on the inducer concentration or gene copy number up to expression levels higher than the expression levels of thegpdApromoter. We also validate the Tet-on system for the generation of conditional overexpression mutants and demonstrate its power when combined with a gene deletion approach. Finally, we show that the system is especially suitable when the functions of essential genes must be examined.

scholarly journals Transcriptional Regulation oficaADBCby both IcaR and TcaR inStaphylococcus epidermidis

2019 ◽  
Vol 201 (6) ◽  
Author(s):  
Tra-My Hoang ◽  
C. Zhou ◽  
J. K. Lindgren ◽  
M. R. Galac ◽  
B. Corey ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Constitutive Expression ◽  
Skin Surface ◽  
Fine Tuning ◽  
Transcriptional Repressors ◽  
Content Type ◽  
Expression Levels ◽  
Dnase I Footprinting ◽  
Genetic Mechanisms ◽  
Operon Expression

ABSTRACTS. epidermidisis a primary cause of biofilm-mediated infections in humans due to adherence to foreign bodies. A major staphylococcal biofilm accumulation molecule is polysaccharide intracellular adhesin (PIA), which is synthesized by enzymes encoded by theicaADBCoperon. Expression of PIA is highly variable among clinical isolates, suggesting that PIA expression levels are selected in certain niches of the host. However, the mechanisms that govern enhancedicaADBCtranscription and PIA synthesis in these isolates are not known. We hypothesized that enhanced PIA synthesis in these isolates was due to function of IcaR and/or TcaR. Thus, twoS. epidermidisisolates (1457 and CSF41498) with differenticaADBCtranscription and PIA expression levels were studied. Constitutive expression of bothicaRandtcaRdemonstrated that both repressors are functional and can completely repressicaADBCtranscription in both 1457 and CSF41498. However, it was found that IcaR was the primary repressor for CSF41498 and TcaR was the primary repressor for 1457. Further analysis demonstrated thaticaRtranscription was repressed in 1457 in comparison to CSF41498, suggesting that TcaR functions as a repressor only in the absence of IcaR. Indeed, DNase I footprinting suggests IcaR and TcaR may bind to the same site within theicaR-icaAintergenic region. Lastly, we found mutants expressing variable amounts of PIA could rapidly be selected from both 1457 and CSF41498. Collectively, we propose that strains producing enhanced PIA synthesis are selected within certain niches of the host through several genetic mechanisms that function to repressicaRtranscription, thus increasing PIA synthesis.IMPORTANCEStaphylococcus epidermidisis a commensal bacterium that resides on our skin. As a commensal, it protects humans from bacterial pathogens through a variety of mechanisms. However, it is also a significant cause of biofilm infections due to its ability to bind to plastic. Polysaccharide intercellular adhesin is a significant component of biofilm, and we propose that the expression of this polysaccharide is beneficial in certain host niches, such as providing extra strength when the bacterium is colonizing the lumen of a catheter, and detrimental in others, such as colonization of the skin surface. We show here that fine-tuning oficaADBCtranscription, and thus PIA synthesis, is mediated via two transcriptional repressors, IcaR and TcaR.

scholarly journals Functional Analysis of the FOXO3 Gene on the Induction of Fetal Hemoglobin in K562 Cells

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2390-2390
Author(s):  
Flávia Peixoto Albuquerque ◽  
Pedro Luis Franca-Neto ◽  
Rafael de Oliveira Franca ◽  
Aderson da Silva Araujo ◽  
Fernando F. Costa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Conflicts Of Interest ◽  
Statistical Significance ◽  
Expression System ◽  
Clinical Manifestations ◽  
Constitutive Expression ◽  
Fetal Hemoglobin ◽  
No Production ◽  
Clinical Prognosis ◽  
Expression Levels

Abstract The β-hemoglobinopathies are known as genetic disorders of high impact and wide distribution worldwide, with chronic and variable clinical prognosis. These pathologies have their symptoms and sequelae alleviated by increased levels of fetal hemoglobin (HbF; α2γ2). The Hydroxyurea, a drug used for the treatment of β-hemoglobinopathies, is effective for the maintenance and control of the development of the main clinical manifestations, however, it needs some prerequisites for its use, which indicates the need for new therapeutic approaches for this group of individuals. The family of Forkhead Box O transcription factors (FOXO), composed of FOXO1, FOXO3, FOXO4 and FOXO6, plays a key role in the regulation of several biological processes such as: regulation of the cell cycle, modulation oxidative stress, regulation mechanisms of response to DNA damage, controlling apoptosis and inflammatory response. Among members of the FOXO family, FOXO3 has been described as a physiological regulator of the erythroid maturation process and indicated as a positive regulator of HbF levels. In the present work, we evaluated the expression levels of the FOXO3 gene in patients with hemoglobinopathies and, in an attempt to better understand the pathophysiology of the disease, we performed a subcloning of the FOXO3 gene into a lentiviral expression system for its constitutive expression in vitro and subsequent evaluation of its activity as a possible transcription factor for γ globin genes (HBG1 and HBG2). In our clinical study, FOXO3 expression was significantly higher in patients with sickle cell anemia when compared to healthy donors (HbAA) (P <0.001) . In addition, a differential expression of FOXO3 was associated with the development of lower limb ulcer (P <0.005). Although we observed a tendency to increase FOXO3 expression in patients with 2 or more clinical manifestations, this association was not statistically significant (P = 0.06). The same was observed when we compared the number of clinical complications presented by patients last year with HbF levels: patients with 2 or more complications had lower levels of HbF, although this difference did not reach statistical significance (P = 0.182). There was no correlation between FOXO3 expression levels and HbF dosage (r = -0.12). Because of the activity of the FOXO3 gene in the control of oxidative stress, experiments were performed to evaluate the ROS and NO rates in the cell culture and a significant role was found, the FOXO3 increasing NO production (P = 0.0001) as well as in control of ROS produced in mitochondria. Disclosures No relevant conflicts of interest to declare.

High Level Expression of Active Human Prothrombin in a Vaccina Virus Expression System

1992 ◽  
Vol 68 (02) ◽  
pp. 119-124 ◽  
Author(s):  
F G Falkner ◽  
P L Turecek ◽  
R T A MacGillivray ◽  
W Bodemer ◽  
F Scheiflinger ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Cell Lines ◽  
Expression System ◽  
Human Cell Line ◽  
Cell System ◽  
Time Saving ◽  
Expression Levels ◽  
Mammalian Cell Lines ◽  
Cell Line Hela ◽  
Virus Expression

SummaryWe have worked out an efficient and time saving procedure for the expression of recombinant human prothrombin. The glycoprotein was expressed in the vaccinia virus expression system in several mammalian cell lines. The kidney cell lines Vero and BHK and the human cell line Hela were found to efficiently secrete prothrombin. Expression levels of 3–4 µg of factor II per 106 cells per day corresponding to 18–23 mU per 106 cells per day were achieved. Since the expression levels obtained with the vaccinia virus/Vero cell system were comparable to those obtained in amplified transformed CHO cells it provides an alternative system for the efficient expression of human prothrombin and may allow to further elucidate structure-function relationships of (pro)thrombin and its various effectors.

scholarly journals Gene Expression Space Shapes the Bioprocess Trade-Offs among Titer, Yield and Productivity

2021 ◽  
Vol 11 (13) ◽  
pp. 5859
Author(s):  
Fernando N. Santos-Navarro ◽  
Yadira Boada ◽  
Alejandro Vignoni ◽  
Jesús Picó
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Performance Metrics ◽  
Cell Mass ◽  
Gene Copy ◽  
Substrate Uptake ◽  
Promoter Strength ◽  
Expression Levels ◽  
Trade Offs ◽  
Wide Range

Optimal gene expression is central for the development of both bacterial expression systems for heterologous protein production, and microbial cell factories for industrial metabolite production. Our goal is to fulfill industry-level overproduction demands optimally, as measured by the following key performance metrics: titer, productivity rate, and yield (TRY). Here we use a multiscale model incorporating the dynamics of (i) the cell population in the bioreactor, (ii) the substrate uptake and (iii) the interaction between the cell host and expression of the protein of interest. Our model predicts cell growth rate and cell mass distribution between enzymes of interest and host enzymes as a function of substrate uptake and the following main lab-accessible gene expression-related characteristics: promoter strength, gene copy number and ribosome binding site strength. We evaluated the differential roles of gene transcription and translation in shaping TRY trade-offs for a wide range of expression levels and the sensitivity of the TRY space to variations in substrate availability. Our results show that, at low expression levels, gene transcription mainly defined TRY, and gene translation had a limited effect; whereas, at high expression levels, TRY depended on the product of both, in agreement with experiments in the literature.

scholarly journals A Constitutive Expression System for Cellulase Secretion in Escherichia coli and Its Use in Bioethanol Production

PLoS ONE ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. e0119917 ◽  
Author(s):  
Neha Munjal ◽  
Kamran Jawed ◽  
Saima Wajid ◽  
Syed Shams Yazdani
Keyword(s):  
Escherichia Coli ◽  
Expression System ◽  
Constitutive Expression ◽  
Bioethanol Production ◽  
Cellulase Secretion

scholarly journals Use of a Beet necrotic yellow vein virus RNA-5-derived replicon as a new tool for gene expression

2005 ◽  
Vol 86 (2) ◽  
pp. 463-467 ◽  
Author(s):  
Laure Schmidlin ◽  
Didier Link ◽  
Jérôme Mutterer ◽  
Hubert Guilley ◽  
David Gilmer
Keyword(s):  
Gene Expression ◽  
Recombinant Proteins ◽  
Expression System ◽  
Green Fluorescence Protein ◽  
Yellow Vein ◽  
Expression Levels ◽  
Virus Rna ◽  
New Gene ◽  
Infected Cells ◽  
Fluorescence Protein

A new gene-expression system based on RNA-5 of Beet necrotic yellow vein virus (BNYVV) was constructed to allow the expression of recombinant proteins in virally infected cells. Replication and expression levels of the RNA-5-based replicon containing the green fluorescence protein (GFP) gene were compared with those obtained with the well-characterized RNA-3-derived replicon (Rep-3). When RNA-3 and/or RNA-4 BNYVV RNAs were added to the inoculum, the expression levels of RNA-5-encoded GFP were considerably reduced. To a lesser extent, RNA-3-derived GFP expression was also affected by the presence of RNA-4 and -5. Both RNA-3- and RNA-5-derived molecules were able to express proteins within the same infected cells. Together with Rep-3, the RNA-5-derived replicon thus provides a new tool for the co-expression of different recombinant proteins. In Beta macrocarpa, Rep-5-GFP was able to move in systemic tissues in the presence of RNA-3 and thus provides a new expression system that is not restricted to the inoculated leaves.

scholarly journals A constitutive expression system for glycosyl hydrolase family 7 cellobiohydrolases in Hypocrea jecorina

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Jeffrey G Linger ◽  
Larry E Taylor ◽  
John O Baker ◽  
Todd Vander Wall ◽  
Sarah E Hobdey ◽  
...  
Keyword(s):  
Glycosyl Hydrolase ◽  
Expression System ◽  
Constitutive Expression ◽  
Hypocrea Jecorina ◽  
Glycosyl Hydrolase Family ◽  
Hydrolase Family

scholarly journals Constructing a DNAzyme Delivery and Expression System for Escherichia coli: A Prototype for Phage Therapy

2021 ◽  
Vol 2 (2) ◽  
pp. 19-25
Author(s):  
Hugo V. C. Oliveira ◽  
Spartaco Astolfi-Filho ◽  
Edmar V. Andrade
Keyword(s):  
Escherichia Coli ◽  
Protein Delivery ◽  
Phage Therapy ◽  
Leukemia Virus ◽  
Expression System ◽  
Constitutive Expression ◽  
Primary Component ◽  
Morphological Pattern ◽  
Filamentous Form ◽  
E Coli

Antisense oligonucleotides exhibit high potential for use as therapeutic agents. '10-23' DNAzymes are antisense molecules with a high chemical stability and catalytic efficiency. In the present study, we developed a phagemid containing a DNAzyme expression system regulated by two promoters. One of these promoters, pA1, promotes constitutive expression of Moloney murine leukemia virus reverse transcriptase (MoMuLV-RT). The other promoter, plac, regulates transcription of the RNA substrate from which MoMuLV-RT produces the DNAzyme by reverse transcription. The ftsZ DNAzyme was used to validate this expression system in the phagemid, named pDESCP. ftsZ DNAzyme expression altered the morphological pattern of Escherichia coli from a bacillary to filamentous form. In E. coli FtsZ is the primary component of the cell division apparatus, forming a structure known as Z-ring, which is the place of division. It is suggested that the DNAzyme ftsZ is decreasing the translation of this protein. Delivery of pDESCP into F+ strain of E. coli cells, using VCSM13, and the possible insertion of other DNAzymes into the cassette makes this phagemid an important prototype for phage therapy.

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