scholarly journals Targeted Gene Disruption of the 14-α Sterol Demethylase (cyp51A) in Aspergillus fumigatus and Its Role in Azole Drug Susceptibility

2005 ◽  
Vol 49 (6) ◽  
pp. 2536-2538 ◽  
Author(s):  
E. Mellado ◽  
G. Garcia-Effron ◽  
M. J. Buitrago ◽  
L. Alcazar-Fuoli ◽  
M. Cuenca-Estrella ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Type Strain ◽  
Gene Disruption ◽  
Wild Type Strain ◽  
Drug Susceptibility ◽  
Wild Type ◽  
Targeted Disruption ◽  
Targeted Gene Disruption ◽  
Resistant Strains

ABSTRACT The role of Aspergillus fumigatus 14α-sterol demethylase (Cyp51A) in azole drug susceptibility was assessed. Targeted disruption of cyp51A in azole-susceptible and -resistant strains decreased MICs from 2- to 40-fold. The cyp51A mutants were morphologically indistinguishable from the wild-type strain, retaining the ability to cause pulmonary disease in neutropenic mice.

scholarly journals A Point Mutation in the 14α-Sterol Demethylase Gene cyp51A Contributes to Itraconazole Resistance in Aspergillus fumigatus

2003 ◽  
Vol 47 (3) ◽  
pp. 1120-1124 ◽  
Author(s):  
T. M. Diaz-Guerra ◽  
E. Mellado ◽  
M. Cuenca-Estrella ◽  
J. L. Rodriguez-Tudela
Keyword(s):  
Amino Acid ◽  
Aspergillus Fumigatus ◽  
Point Mutation ◽  
Resistant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Gene Copy ◽  
Wild Type ◽  
Genes Encoding ◽  
Resistant Strains

ABSTRACT The genes encoding 14α-sterol demethylases (cyp51A and cyp51B) were analyzed in 12 itraconazole (ITC)-resistant and three ITC-susceptible clinical isolates of Aspergillus fumigatus. Six ITC-resistant strains exhibited a substitution of another amino acid for glycine at position 54, which is located at a very conserved region of the Cyp51A protein. The cyp51A gene from the A. fumigatus wild-type strain (CM-237) was replaced with the mutated cyp51A gene copy of an ITC-resistant strain (AF-72). Two transformants exhibited resistance to ITC, both of which had incorporated the mutated copy of the cyp51A gene.

Role of melanotransferrin in iron metabolism: studies using targeted gene disruption in vivo

Blood ◽  
2006 ◽  
Vol 107 (7) ◽  
pp. 2599-2601 ◽  
Author(s):  
Eric O. Sekyere ◽  
Louise L. Dunn ◽  
Yohan Suryo Rahmanto ◽  
Des R. Richardson
Keyword(s):  
Metabolic Pathways ◽  
Gene Disruption ◽  
Vital Role ◽  
Plasminogen Activation ◽  
Serum Chemistry ◽  
Wild Type ◽  
Targeted Disruption ◽  
Targeted Gene Disruption

AbstractMelanotransferrin (MTf) or tumor antigen p97 is a transferrin homolog that binds one iron (Fe) atom and has been suggested to play roles in a variety of processes, including Fe metabolism, eosinophil differentiation, and plasminogen activation. Considering the vital role of Fe in many metabolic pathways, such as DNA and heme synthesis, it is important to understand the function of MTf. To define this, a MTf knockout (MTf–/–) mouse was generated through targeted disruption of the MTf gene. The MTf–/– mice were viable and fertile and developed normally, with no morphologic or histologic abnormalities. Assessment of Fe indices, tissue Fe levels, hematology, and serum chemistry parameters demonstrated no differences between MTf–/– and wild-type (MTf+/+) mice, suggesting MTf was not essential for Fe metabolism.

scholarly journals Role of Aspergillus lentulus 14-α Sterol Demethylase (Cyp51A) in Azole Drug Susceptibility

2011 ◽  
Vol 55 (12) ◽  
pp. 5459-5468 ◽  
Author(s):  
Emilia Mellado ◽  
Laura Alcazar-Fuoli ◽  
Manuel Cuenca-Estrella ◽  
Juan L. Rodriguez-Tudela
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Gene Knockout ◽  
Corticosteroid Treatment ◽  
Drug Susceptibility ◽  
Wild Type ◽  
Primary Resistance ◽  
Content Type ◽  
Aspergillus Lentulus

ABSTRACTRecent studies have demonstrated that some morphologically atypicalAspergillus fumigatusstrains are different species belonging to the sectionFumigati.Aspergillus lentulus, one of these sibling species, is increasingly reported in patients under corticosteroid treatment. MICs of most antifungals in clinical use are elevated againstA. lentulus, and it shows primary resistance to azole drugs. TwoA. lentuluscytochrome P450 14-α sterol demethylases, encoded byA. lentuluscyp51A (Alcyp51A) and Alcyp51Bgenes, were identified. Targetedcyp51Agene knockout inA. lentulusshowed that the intrinsic azole resistance of this species iscyp51Adependent. The Δcyp51Astrain was morphologically indistinguishable from theA. lentuluswild-type strain, retaining the ability to cause pulmonary disease in neutropenic mice. The heterologous expression ofA. lentuluscyp51Awas performed in anA. fumigatuscyp51A-deficient strain, confirming that Cyp51A is responsible for the differences inA. lentulus-azole drug interaction.

scholarly journals Role Of Selected Fimbrial Adheins In Pathogenesis Of Acid-Induced Eneterohemorrhagic Escherichia Coli 0157:H7

2021 ◽  
Author(s):  
Shahnaz Haque
Keyword(s):  
Fatty Acid ◽  
Type Strain ◽  
Wild Type Strain ◽  
Short Chain Fatty Acid ◽  
Acid Stress ◽  
Chain Fatty Acid ◽  
Short Chain ◽  
Wild Type ◽  
Food Borne

Enterohemorrhagic Escherichia coli (EHEC) 0157:H7 is a food-borne pathogen that causes hemolytic uremic syndrome and hemorrhagic colitis. The mechanisms underlying the adhesion of EHEC 0157:H7 to intestinal epithelial cells are not well understood. Like other food-borne pathogens, ECEC 0157:H7 must survive the acid stress of the gastric juice in the stomach and short chain fatty acid in the intestine in order to colonize the large intestine. We have found that acid stress and short chain fatty acid stress significantly enhance host-adhesion of EHEC 0157:H7 and also upregulates expression of EHEC fimbrial genes, lpfA1, lpfA2 and yagZ, as demonstrated by our DNA microarray. We now report that disruption of the yagZ (also known as the E. coli common pilus A) gene results in loss of the acid-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the sress-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the stress-induced adhesion pehnotype is restored, confirming the role of yagZ in the acid as well as short chain fatty acid induced adhesion to HEp-2 cells. On the other hand, neither disruption in the long polar fimbria genes lpfA1 or lpfA2 in the wild type showed any effect in adherence to HEp-2 cells; rather displaying a hyperadherant phenotype to HEp-2 cells after acid-induced or short chain fatty acid-induced stress. The results also indicate that acid or short chain fatty acid stress, which is a part of the host's natural defense mechanism against pathogens, may regulate virulence factors resulting in enhanced bacteria-host attachment during colonization in the human or bovine host.

scholarly journals Role of CpALS4790 and CpALS0660 in Candida parapsilosis Virulence: Evidence from a Murine Model of Vaginal Candidiasis

2020 ◽  
Vol 6 (2) ◽  
pp. 86
Author(s):  
Marina Zoppo ◽  
Fabrizio Fiorentini ◽  
Cosmeri Rizzato ◽  
Mariagrazia Di Luca ◽  
Antonella Lupetti ◽  
...  
Keyword(s):  
Cell Wall ◽  
Murine Model ◽  
Type Strain ◽  
Wild Type Strain ◽  
Candida Parapsilosis ◽  
Vaginal Candidiasis ◽  
Phenotypic Characterization ◽  
Wild Type ◽  
Mutant Strains

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

scholarly journals The RcsCB His-Asp Phosphorelay System Is Essential To Overcome Chlorpromazine-Induced Stress in Escherichia coli

2002 ◽  
Vol 184 (10) ◽  
pp. 2850-2853 ◽  
Author(s):  
Annie Conter ◽  
Rachel Sturny ◽  
Claude Gutierrez ◽  
Kaymeuang Cam
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cell Envelope ◽  
Wild Type ◽  
E Coli ◽  
Induced Stress ◽  
Mutant Strains ◽  
Molecular Nature

ABSTRACT The RcsCB His-Asp phosphorelay system regulates the expression of several genes of Escherichia coli, but the molecular nature of the inducing signal is still unknown. We show here that treatment of an exponentially growing culture of E. coli with the cationic amphipathic compound chlorpromazine (CPZ) stimulates expression of a set of genes positively regulated by the RcsCB system. This induction is abolished in rcsB or rcsC mutant strains. In addition, treatment with CPZ inhibits growth. The wild-type strain is able to recover from this inhibition and resume growth after a period of adaptation. In contrast, strains deficient in the RcsCB His-Asp phosphorelay system are hypersensitive to CPZ. These results suggest that cells must express specific RcsCB-regulated genes in order to cope with the CPZ-induced stress. This is the first report of the essential role of the RcsCB system in a stress situation. These results also strengthen the notion that alterations of the cell envelope induce a signal recognized by the RcsC sensor.

scholarly journals Role of Calcineurin in Stress Resistance, Morphogenesis, and Virulence of a Candida albicans Wild-Type Strain

2006 ◽  
Vol 74 (7) ◽  
pp. 4366-4369 ◽  
Author(s):  
Teresa Bader ◽  
Klaus Schröppel ◽  
Stefan Bentink ◽  
Nina Agabian ◽  
Gerwald Köhler ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Type Strain ◽  
Pulmonary Infection ◽  
Wild Type Strain ◽  
Selection Marker ◽  
Wild Type ◽  
Environmental Signals ◽  
Successful Infection ◽  
Strain Sc5314

ABSTRACT By generating a calcineurin mutant of the Candida albicans wild-type strain SC5314 with the help of a new recyclable dominant selection marker, we confirmed that calcineurin mediates tolerance to a variety of stress conditions but is not required for the ability of C. albicans to switch to filamentous growth in response to hypha-inducing environmental signals. While calcineurin was essential for virulence of C. albicans in a mouse model of disseminated candidiasis, deletion of CMP1 did not significantly affect virulence during vaginal or pulmonary infection, demonstrating that the requirement for calcineurin for a successful infection depends on the host niche.

scholarly journals Fructose Utilization and Phytopathogenicity of Spiroplasma citri

2000 ◽  
Vol 13 (10) ◽  
pp. 1145-1155 ◽  
Author(s):  
Patrice Gaurivaud ◽  
Jean-Luc Danet ◽  
Frédéric Laigret ◽  
Monique Garnier ◽  
Joseph M. Bové
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Carbon Sources ◽  
Wild Type ◽  
Spiroplasma Citri ◽  
Companion Cells ◽  
Transmission Period ◽  
Sieve Tubes ◽  
Sucrose Loading

Spiroplasma citri is a plant-pathogenic mollicute. Recently, the so-called nonphytopathogenic S. citri mutant GMT 553 was obtained by insertion of transposon Tn4001 into the first gene of the fructose operon. Additional fructose operon mutants were produced either by gene disruption or selection of spontaneous xylitol-resistant strains. The behavior of these spiroplasma mutants in the periwinkle plants has been studied. Plants infected via leafhoppers with the wild-type strain GII-3 began to show symptoms during the first week following the insect-transmission period, and the symptoms rapidly became severe. With the fructose operon mutants, symptoms appeared only during the fourth week and remained mild, except when reversion to a fructose+ phenotype occurred. In this case, the fructose+ revertants quickly overtook the fructose¯ mutants and the symptoms soon became severe. When mutant GMT 553 was complemented with the fructose operon genes that restore fructose utilization, severe pathogenicity, similar to that of the wild-type strain, was also restored. Finally, plants infected with the wild-type strain and grown at 23°C instead of 30°C showed late symptoms, but these rapidly became severe. These results are discussed in light of the role of fructose in plants. Fructose utilization by the spiroplasmas could impair sucrose loading into the sieve tubes by the companion cells and result in accumulation of carbohydrates in source leaves and depletion of carbon sources in sink tissues.

scholarly journals Evidence for Contribution of Neutral Trehalase in Barotolerance of Saccharomyces cerevisiae

2000 ◽  
Vol 66 (12) ◽  
pp. 5182-5185 ◽  
Author(s):  
Hitoshi Iwahashi ◽  
Solomon Nwaka ◽  
Kaoru Obuchi
Keyword(s):  
Hydrostatic Pressure ◽  
Stationary Phase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Glucose Repression ◽  
Logarithmic Phase ◽  
Wild Type ◽  
Neutral Trehalase ◽  
I Gene

ABSTRACT In yeast, trehalose accumulation and its hydrolysis, which is catalyzed by neutral trehalase, are believed to be important for thermotolerance. We have shown that trehalose is one of the important factors for barotolerance (resistance to hydrostatic pressure); however, nothing is known about the role of neutral trehalase in barotolerance. To estimate the contribution of neutral trehalase in resisting high hydrostatic pressure, we measured the barotolerance of neutral trehalase I and/or neutral trehalase II deletion strains. Under 180 MPa of pressure for 2 h, the neutral trehalase I deletion strain showed higher barotolerance in logarithmic-phase cells and lower barotolerance in stationary-phase cells than the wild-type strain. Introduction of the neutral trehalase I gene (NTH1) into the deletion mutant restored barotolerance defects in stationary-phase cells. Furthermore, we assessed the contribution of neutral trehalase during pressure and recovery conditions by varying the expression ofNTH1 or neutral trehalase activity with a galactose-inducible GAL1 promoter with either glucose or galactose. The low barotolerance observed with glucose repression of neutral trehalase from the GAL1 promoter was restored during recovery with galactose induction. Our results suggest that neutral trehalase contributes to barotolerance, especially during recovery.

scholarly journals Role of β-Lactamases and Porins in Resistance to Ertapenem and Other β-Lactams in Klebsiella pneumoniae

2004 ◽  
Vol 48 (8) ◽  
pp. 3203-3206 ◽  
Author(s):  
George A. Jacoby ◽  
Debra M. Mills ◽  
Nancy Chow
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
Resistant Mutants ◽  
High Level ◽  
Level Resistance

ABSTRACT High-level resistance to ertapenem was produced by β-lactamases of groups 1, 2f, and 3 in a strain of Klebsiella pneumoniae deficient in Omp35 and Omp36. From a wild-type strain producing ACT-1 β-lactamase, ertapenem-resistant mutants for which the ertapenem MICs were up to 128 μg/ml and expression of outer membrane proteins was diminished could be selected.

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