scholarly journals Teicoplanin Stress-Selected Mutations Increasing ςB Activity in Staphylococcus aureus

2001 ◽  
Vol 45 (6) ◽  
pp. 1714-1720 ◽  
Author(s):  
Markus Bischoff ◽  
Brigitte Berger-Bächi
Keyword(s):  
Staphylococcus Aureus ◽  
Target Genes ◽  
Point Mutations ◽  
Pigment Formation ◽  
Genetic Manipulations ◽  
Alternative Transcription ◽  
Selection For ◽  
Dehydrosqualene Synthase ◽  
Promoter Mutations ◽  
Orange Color

ABSTRACT A natural rsbU mutant of Staphylococcus aureus, unable to activate the alternative transcription factor ςB via the RsbU pathway and therefore forming unpigmented colonies, produced first-step teicoplanin-resistant mutants upon selection for growth in the presence of teicoplanin, of which the majority were of an intense orange color. By using an asp23promoter-luciferase fusion as an indicator, the pigmented mutants were shown to express increased ςB activity. Increased ςB activity was associated with point mutations inrsbW, releasing ςB from sequestration by the anti-sigma factor RsbW, or to promoter mutations increasing the ςB/RsbW ratio. Genetic manipulations involving thesigB operon suggested that the mutations within the operon were associated with the increase in teicoplanin resistance. The upregulation of ςB suggests that a ςB-controlled gene(s) is directly or indirectly involved in the development of teicoplanin resistance in S. aureus. Carotenoids do not contribute to teicoplanin resistance, since inactivation of the dehydrosqualene synthase gene crtMabolished pigment formation without affecting teicoplanin resistance. The relevant ςB-controlled target genes involved in teicoplanin resistance remain to be identified.

scholarly journals Reconstruction ofmreBExpression in Staphylococcus aureus via a Collection of New Integrative Plasmids

2014 ◽  
Vol 80 (13) ◽  
pp. 3868-3878 ◽  
Author(s):  
Ana Yepes ◽  
Gudrun Koch ◽  
Andrea Waldvogel ◽  
Juan-Carlos Garcia-Betancur ◽  
Daniel Lopez
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Protein Localization ◽  
Antibiotic Resistance Genes ◽  
Wall Material ◽  
Content Type ◽  
Genetic Manipulations ◽  
Discrete Structures

ABSTRACTProtein localization has been traditionally explored in unicellular organisms, whose ease of genetic manipulation facilitates molecular characterization. The two rod-shaped bacterial modelsEscherichia coliandBacillus subtilishave been prominently used for this purpose and have displaced other bacteria whose challenges for genetic manipulation have complicated any study of cell biology. Among these bacteria is the spherical pathogenic bacteriumStaphylococcus aureus. In this report, we present a new molecular toolbox that facilitates gene deletion in staphylococci in a 1-step recombination process and additional vectors that facilitate the insertion of diverse reporter fusions into newly identified neutral loci of theS. aureuschromosome. Insertion of the reporters does not add any antibiotic resistance genes to the chromosomes of the resultant strains, thereby making them amenable for further genetic manipulations. We used this toolbox to reconstitute the expression ofmreBinS. aureus, a gene that encodes an actin-like cytoskeletal protein which is absent in coccal cells and is presumably lost during the course of speciation. We observed that inS. aureus, MreB is organized in discrete structures in association with the membrane, leading to an unusual redistribution of the cell wall material. The production of MreB also caused cell enlargement, but it did not revert staphylococcal shape. We present interactions of MreB with key staphylococcal cell wall-related proteins. This work facilitates the useS. aureusas a model system in exploring diverse aspects of cellular microbiology.

Enterotoxin B formation by fermentation mutants of Staphylococcus aureus

1976 ◽  
Vol 22 (2) ◽  
pp. 182-188
Author(s):  
Robert A. Altenbern
Keyword(s):  
Staphylococcus Aureus ◽  
Point Mutations ◽  
Type A ◽  
Enterotoxin B

An appreciable fraction of carbohydrate-negative (car) mutants of Staphylococcus aureus strains ATCC 14458,778, and S-6 exhibit increased enterotoxin B (SEB) production. In addition, some lac and mtl mutants of these strains also display enhanced SEB formation. All such mutants appear to be point mutations. Mutagen-induced reversions of high SEB producing car, mtl, or lac mutants yield varying amounts of SEB and some clones seem to be restored to the characteristics of the parent type. A few sequentially isolated lac, mtl double mutants of strain 778 elaborate much more or much less SEB than either the lac or the mtl single mutants.

Screening candidate microR-15a- IRAK2 regulatory pairs for predicting the response to Staphylococcus aureus-induced mastitis in dairy cows

2019 ◽  
Vol 86 (4) ◽  
pp. 425-431 ◽  
Author(s):  
Zhi Chen ◽  
Jingpeng Zhou ◽  
Xiaolong Wang ◽  
Yang Zhang ◽  
Xubin Lu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Differential Expression ◽  
High Throughput Sequencing ◽  
Target Genes ◽  
Interleukin 1 ◽  
Differentially Expressed ◽  
Luciferase Reporter ◽  
Expression Of Genes ◽  
Chinese Holstein Cows ◽  
Reporter Assays

AbstractWe established a mastitis model using exogenous infection of the mammary gland of Chinese Holstein cows with Staphylococcus aureus and extracted total RNA from S. aureus-infected and healthy mammary quarters. Differential expression of genes due to mastitis was evaluated using Affymetrix technology and results revealed a total of 1230 differentially expressed mRNAs. A subset of affected genes was verified via Q-PCR and pathway analysis. In addition, Solexa high-throughput sequencing technology was used to analyze profiles of miRNA in infected and healthy quarters. These analyses revealed a total of 52 differentially expressed miRNAs. A subset of those results was verified via Q-PCR. Bioinformatics techniques were used to predict and analyze the correlations among differentially expressed miRNA and mRNA. Results revealed a total of 329 pairs of negatively associated miRNA/mRNA, with 31 upregulated pairs of mRNA and 298 downregulated pairs of mRNA. Differential expression of miR-15a and interleukin-1 receptor-associated kinase-like 2 (IRAK2), were evaluated by western blot and luciferase reporter assays. We conclude that miR-15a and miR-15a target genes (IRAK2) constitute potential miRNA–mRNA regulatory pairs for use as biomarkers to predict a mastitis response.

scholarly journals Causal Role of Single Nucleotide Polymorphisms within themprFGene of Staphylococcus aureus in Daptomycin Resistance

2013 ◽  
Vol 57 (11) ◽  
pp. 5658-5664 ◽  
Author(s):  
Soo-Jin Yang ◽  
Nagendra N. Mishra ◽  
Aileen Rubio ◽  
Arnold S. Bayer
Keyword(s):  
Staphylococcus Aureus ◽  
Single Nucleotide Polymorphisms ◽  
Point Mutations ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Single Nucleotide ◽  
Content Type ◽  
Reading Frame ◽  
A Charge

ABSTRACTSingle nucleotide polymorphisms (SNPs) within themprFopen reading frame (ORF) have been commonly observed in daptomycin-resistant (DAPr)Staphylococcus aureusstrains. Such SNPs are usually associated with a gain-in-function phenotype, in terms of either increased synthesis or enhanced translocation (flipping) of lysyl-phosphatidylglycerol (L-PG). However, it is unclear if suchmprFSNPs are causal in DAPrstrains or are merely a biomarker for this phenotype. In this study, we used an isogenic set ofS. aureusstrains: (i) Newman, (ii) its isogenic ΔmprFmutant, and (iii) several intransplasmid complementation constructs, expressing either a wild-type or point-mutated form of themprFORF cloned from two isogenic DAP-susceptible (DAPs)-DAPrstrain pairs (616-701 and MRSA11/11-REF2145). Complementation of the ΔmprFstrain with singly point-mutatedmprFgenes (mprFS295LormprFT345A) revealed that (i) individual and distinct point mutations within themprFORF can recapitulate phenotypes observed in donor strains (i.e., changes in DAP MICs, positive surface charge, and cell membrane phospholipid profiles) and (ii) these gain-in-function SNPs (i.e., enhanced L-PG synthesis) likely promote reduced DAP binding toS. aureusby a charge repulsion mechanism. Thus, for these two DAPrstrains, the definedmprFSNPs appear to be causally related to this phenotype.

scholarly journals Transcriptional Profiling Analysis of the Global Regulator NorG, a GntR-Like Protein of Staphylococcus aureus

2011 ◽  
Vol 193 (22) ◽  
pp. 6207-6214 ◽  
Author(s):  
Q. C. Truong-Bolduc ◽  
P. M. Dunman ◽  
T. Eidem ◽  
D. C. Hooper
Keyword(s):  
Staphylococcus Aureus ◽  
Target Genes ◽  
Efflux Pump ◽  
Transcriptional Profiling ◽  
Fold Increase ◽  
Regulatory Function ◽  
Drug Transporter ◽  
Content Type ◽  
Global Regulators ◽  
Inorganic Ion

The GntR-like protein NorG has been shown to affectStaphylococcus aureusgenes involved in resistance to quinolones and β-lactams, such as those encoding the NorB and AbcA transporters. To identify the target genes regulated by NorG, we carried out transcriptional-profiling assays usingS. aureusRN6390 and its isogenicnorG::catmutant. Our data showed that NorG positively affected the transcription of global regulatorsmgrA,arlS, andsarZ. The three putative drug efflux pump genes most positively affected by NorG were the NorB efflux pump (5.1-fold), the MmpL-like protein SACOL2566 (5.2-fold), and the BcrA-like drug transporter SACOL2525 (5.7-fold) genes. TheS. aureuspredicted MmpL protein showed 53% homology with the MmpL lipid transporter ofMycobacterium tuberculosis, and the putative SACOL2525 protein showed 87% homology with the bacitracin drug transporter BcrA ofStaphylococcus hominis. Two pump genes most negatively affected by NorG were the NorC (4-fold) and AbcA (6-fold) genes. Other categories of genes, such as those participating in amino acid, inorganic ion, or nucleotide transporters and metabolism, were also affected by NorG. Real-time reverse transcription (RT)-PCR assays formgrA,arlS,sarZ,norB,norC,abcA,mmpL, andbcrA-like were carried out to verify microarray data and showed the same level of up- or downregulation by NorG. ThenorGmutant showed a 2-fold increase in resistance to norfloxacin and rhodamine, both substrates of the NorC transporter, which is consistent with the resistance phenotype conferred by overexpression ofnorCon a plasmid. These data indicate that NorG has broad regulatory function inS. aureus.

scholarly journals Genetic effects of F1 pollen sterility genes S-b, S-d and S-e in rice (Oryza sativa L.)

2019 ◽  
Vol 55 (No. 2) ◽  
pp. 55-60
Author(s):  
Mingsong Jiang ◽  
Jiandi Xu ◽  
Feng Chen ◽  
Wenyin Zhu
Keyword(s):  
Target Genes ◽  
Oryza Sativa L ◽  
Genetic Effect ◽  
Pollen Sterility ◽  
Experimental Population ◽  
Substitution Lines ◽  
Japonica Variety ◽  
Chromosome Segment Substitution Lines ◽  
Selection For ◽  
Sterility Genes

An experimental population commonly used in genetic analyses of gene or quantitative trait loci (QTLs) in rice is chromosome segment substitution lines (CSSLs). In the present study, with the typical indica variety Guangluai 4 as a donor and japonica variety Taichung 65 as a recipient, seven CSSLs carrying F<sub>1 </sub>pollen sterility genes S-b, S-d, S-e, S-b/S-d, S-b/S-e, S-d/S-e, and S-b/S-d/S-e were obtained by specific selection for the target genes, non-specific selection for the genome of the recurrent parents in four backcross populations (BC<sub>1</sub>F<sub>2</sub>, BC<sub>2</sub>F<sub>2</sub>, BC<sub>3</sub>F<sub>2</sub> and BC<sub>3</sub>F<sub>3</sub>). We evaluated the genetic effect of the F<sub>1</sub> pollen sterility genes using 35 F<sub>1 </sub>hybrid individuals in crosses derived from CSSLs and Taichung 65. Pollen fertility of F<sub>1</sub> hybrid plants was observed and the results indicated that the single genes S-b, S-d and S-e can cause 67.7%, 14.6% and 53.2% of pollen sterility, respectively. Multiple genes S-b/S-d, S-b/S-e, S-d/S-e, and S-b/S-d/S-e can cause 76.6%, 85%, 68.7%, and 93% of pollen sterility, respectively.  

scholarly journals Cubitus interruptus Requires DrosophilaCREB-Binding Protein To Activate wingless Expression in theDrosophila Embryo

2000 ◽  
Vol 20 (5) ◽  
pp. 1616-1625 ◽  
Author(s):  
Yang Chen ◽  
R. H. Goodman ◽  
Sarah M. Smolik
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
Binding Protein ◽  
Point Mutations ◽  
Creb Binding Protein ◽  
Wild Type ◽  
Interaction Domain ◽  
Cubitus Interruptus

ABSTRACT CREB-binding protein (CBP) serves as a transcriptional coactivator in multiple signal transduction pathways. The Drosophilahomologue of CBP, dCBP, interacts with the transcription factors Cubitus interruptus (CI), MAD, and Dorsal (DL) and functions as a coactivator in several signaling pathways during Drosophiladevelopment, including the hedgehog (hh),decapentaplegic (dpp), and Tollpathways. Although dCBP is required for the expression of thehh target genes, wingless (wg) andpatched (ptc) in vivo, and potentiatesci-mediated transcriptional activation in vitro, it is not known that ci absolutely requires dCBP for its activity. We used a yeast genetic screen to identify several ci point mutations that disrupt CI-dCBP interactions. These mutant proteins are unable to transactivate a reporter gene regulated by cibinding sites and have a lower dCBP-stimulated activity than wild-type CI. When expressed exogenously in embryos, the CI point mutants cannot activate endogenous wg expression. Furthermore, a CI mutant protein that lacks the entire dCBP interaction domain functions as a negative competitor for wild-type CI activity, and the expression of dCBP antisense RNAs can suppress CI transactivation in Kc cells. Taken together, our data suggest that dCBP function is necessary forci-mediated transactivation of wg duringDrosophila embryogenesis.

scholarly journals Sequence Analysis of Inducible Prophage phIS3501 Integrated into the Haemolysin II Gene of Bacillus thuringiensis var israelensis ATCC35646

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Bouziane Moumen ◽  
Christophe Nguen-The ◽  
Alexei Sorokin
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Bacillus Thuringiensis ◽  
Bacillus Cereus ◽  
Genomic Organization ◽  
Food Poisoning ◽  
Complete Sequence ◽  
Bacterial Host ◽  
Regulation Of Synthesis ◽  
Selection For

Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequenced genome of Bacillus thuringiensis var israelensis ATCC35646 contains several potentially induced prophages, one of them integrated into the hlyII gene. We determined the complete sequence and established the genomic organization of this prophage-designated phIS3501. During induction of excision of this prophage with mitomycin C, intact hlyII gene is formed, thus providing to cells a genetic ability to synthesize the active toxin. Therefore, this prophage, upon its excision, can be implicated in the regulation of synthesis of the active toxin and thus in the virulence of bacterial host. A generality of selection for such systems in bacterial pathogens is indicated by the similarity of this genetic arrangement to that of Staphylococcus aureus  β-haemolysin.

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