scholarly journals Regulation of Staphylococcus aureus Type 5 and Type 8 Capsular Polysaccharides by CO2

2001 ◽  
Vol 183 (15) ◽  
pp. 4609-4613 ◽  
Author(s):  
Silvia Herbert ◽  
Steven W. Newell ◽  
Chia Lee ◽  
Karsten-Peter Wieland ◽  
Bruno Dassy ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Background ◽  
Capsular Polysaccharide ◽  
Promoter Sequence ◽  
Transcriptional Level ◽  
Marginal Effect ◽  
Promoter Regions ◽  
Sequence Variations ◽  
Derivatives Of

ABSTRACT Staphylococcus aureus expression of capsular polysaccharide type 5 (CP5) has been shown to be downregulated by CO2. Here we show that CO2 reduces CP5 expression at the transcriptional level and that CO2regulates CP8 expression depending on the genetic background of the strains. Growth in the presence of air supplemented with 5% CO2 caused a significant decrease in CP8 expression in fourS. aureus strains, a marginal effect in four strains, and higher CP8 expression in strain Becker. Absolute CP8 expression in the nine S. aureus strains differed largely from strain to strain. Four groups of strains were established due to sequence variations in the promoter region of cap5 andcap8. To test whether these sequence variations are responsible for the different responses to CO2, promoter regions from selected strains were fused to the reporter genexylE in pLC4, and the plasmids were electrotransformed into strains Becker and Newman. XylE activity was negatively regulated by CO2 in all derivatives of strain Newman and was always positively regulated by CO2 in all derivatives of strain Becker. Differences in promoter sequences did not influence the pattern of CP8 expression. Therefore, the genetic background of the strains rather than differences in the promoter sequence determines the CO2 response. trans-acting regulatory molecules may be differentially expressed in strain Becker versus strain Newman. The strain dependency of the CP8 expression established in vitro was also seen in lung tissue sections of patients with cystic fibrosis infected with CP8-positive S. aureus strains.

scholarly journals mgr, a Novel Global Regulator in Staphylococcus aureus

2003 ◽  
Vol 185 (13) ◽  
pp. 3703-3710 ◽  
Author(s):  
Thanh T. Luong ◽  
Steven W. Newell ◽  
Chia Y. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Polyacrylamide Gel Electrophoresis ◽  
Protein A ◽  
Sodium Dodecyl ◽  
Binding Motif ◽  
Transcriptional Level ◽  
Virulence Determinants ◽  
Alpha Toxin ◽  
Extracellular Protein Production

ABSTRACT The virulence determinants of Staphylococcus aureus are coordinately controlled by several unlinked chromosomal loci. Here, we report the identification of CYL5614, derived from strain Becker, with a mutation that affects the expression of type 8 capsular polysaccharide (CP8), nuclease, alpha-toxin, coagulase, protease, and protein A. This novel locus, named mgr, was linked by transposon Tn917 and mapped by three-factorial transduction crosses. The region containing the mgr locus was cloned and sequenced. Deletion mutagenesis and genetic complementation showed that the locus consisted of one gene, mgrA. Interestingly, mgrA-null mutants exhibited a phenotype opposite to that of CYL5614. This was due to a T-to-C mutation upstream of mgrA that resulted in a four- to eightfold increase in mgrA transcription in strain CYL5614. Thus, these results indicate that mgrA is an activator of CP8 and nuclease but a repressor of alpha-toxin, coagulase, protease, and protein A. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed that the mgr locus profoundly affected extracellular protein production, suggesting that the locus may regulate many other genes as well. The translated MgrA protein has a region of significant homology, which includes the helix-turn-helix DNA-binding motif, with the Escherichia coli MarR family of transcriptional regulators. Northern slot blot analyses suggested that mgr affected CP8, alpha-toxin, nuclease, and protein A at the transcriptional level.

scholarly journals USA300 and USA500 Clonal Lineages of Staphylococcus aureus Do Not Produce a Capsular Polysaccharide Due to Conserved Mutations in the cap5 Locus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Xue Li ◽  
Md Tauqeer Alam ◽  
Timothy D. Read ◽  
Julia Sieth ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
The United States ◽  
Whole Genome Sequence ◽  
Content Type ◽  
Capsule Production ◽  
Usa300 Strain

ABSTRACTThe surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed againstStaphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistantS. aureus(MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptibleS. aureus(MSSA) isolates were CP negative (CP−). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP−. Whole-genome sequence analysis of 146 CP−USA300 MRSA isolates revealed they all carry acap5locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in thecap5promoter,cap5Dnucleotide 994, andcap5Enucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same fourcap5mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of thecaploci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specificcap5mutations arose sequentially inS. aureusin a common ancestor of USA300 and USA500 isolates.IMPORTANCEThe USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP−) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP+) phenotype is unlikelyin vivoorin vitrosince it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP−and provide new insight into the evolution of the USA300 and USA500 lineages.

scholarly journals The Search for New Antibacterial Agents among 1,2,3-Triazole Functionalized Ciprofloxacin and Norfloxacin Hybrids: Synthesis, Docking Studies, and Biological Activity Evaluation

2021 ◽  
Vol 90 (1) ◽  
pp. 2
Author(s):  
Halyna Hryhoriv ◽  
Illia Mariutsa ◽  
Sergiy M. Kovalenko ◽  
Victoriya Georgiyants ◽  
Lina Perekhoda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Biological Activity ◽  
Antibacterial Agents ◽  
Docking Studies ◽  
Synthetic Method ◽  
Bacillus Subtilis Atcc ◽  
Resistant Strains ◽  
Derivatives Of

Among all modern antibiotics, fluoroquinolones are well known for their broad spectrums of activity and efficiency toward microorganisms and viruses. However, antibiotic resistance is still a problem, which has encouraged medicinal chemists to modify the initial structures in order to combat resistant strains. Our current work is aimed at synthesizing novel hybrid derivatives of ciprofloxacin and norfloxacin and applying docking studies and biological activity evaluations in order to find active promising molecules. We succeeded in the development of a synthetic method towards 1,2,3-triazole-substituted ciprofloxacin and norfloxacin derivatives. The structure and purity of the obtained compounds were confirmed by 1H NMR, 13C NMR, 19F NMR, LC/MS, UV-, IR- spectroscopy. Docking studies, together with in vitro research against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 27853, Candida albicans NCTC 885-653 revealed compounds in which activity exceeded the initial molecules.

scholarly journals Revisiting the regulation of the capsular polysaccharide biosynthesis gene cluster inStaphylococcus aureus

2019 ◽  
Author(s):  
Daniela Keinhörster ◽  
Andrea Salzer ◽  
Alejandra Duque-Jaramillo ◽  
Shilpa E. George ◽  
Gabriella Marincola ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Expression Pattern ◽  
Inverted Repeat ◽  
Capsular Polysaccharide ◽  
Gene Expression Pattern ◽  
Upstream Region ◽  
Transcriptional Level ◽  
Bacterial Cells ◽  
Biosynthesis Gene Cluster ◽  
Polysaccharide Biosynthesis

AbstractInStaphylococcus aureus, the capsular polysaccharide (CP) protects against phagocytosis, but also hinders adherence to endothelial cells and matrix proteins. Its biosynthesis is tightly controlled resulting in a heterogeneous phenotype within a population and CP being mainly detectable in non-growing cells. Capsular biosynthesis genes are encoded by a conservedcapA-Poperon whose expression is driven by an upstream promoter element (Pcap) in front ofcapA. The organization of Pcapis poorly understood, as is the interplay of different regulators that influence the early-Off/late-Heterogeneouscaptranscription pattern. Here, we demonstrate that Pcapcontains a main SigB-dependent promoter. The SigB consensus motif overlaps with a previously described inverted repeat that is crucial forcapexpression. The essentiality of the inverted repeat is derived from this region acting as a SigB binding site rather than as an operator site for the proposedcapactivators RbsR and MsaB. Furthermore, Pcapcontains an extensive upstream region harboring a weak SigA-dependent promoter and binding sites for thecaprepressors SaeR, CodY and Rot. We show that heterogeneous CP synthesis is determined by the combination of SigB activity and repressor binding to the upstream region. The direct SigB dependency and the upstream repressors are also sufficient to explain the temporal gene expression pattern at the transcriptional level. However, CP synthesis remains growth phase-dependent even whencapAtranscription is rendered constitutive, suggesting additional post-transcriptional regulatory circuits. Thus, the interference of multiple repressors with SigB-dependent promoter activity as well as post-transcriptional mechanisms ensure the appropriate regulation of CP synthesis.ImportanceThe majority of bacterial pathogens produce an array of polysaccharides on their surface which are important virulence factors and thus serve as attractive vaccine candidates. However, the synthesis and assembly of these structures is highly variable and tightly regulated at various levels. In the human pathogenStaphylococcus aureus, the synthesis of the capsular polysaccharide (CP) is dependent on a complex regulatory network which ensures that CP is produced only in a fraction of stationary phase cells. Here, we determined main regulators that drive the peculiar CP expression pattern. We found that the interplay of the transcriptional repressors Sae, CodY and Rot with the alternative Sigma factor B is responsible for early-Off/late-Heterogeneous expression at the transcriptional level. The data also implicates post-transcriptional mechanisms that may act to avoid conflict in precursor usage by machineries involved in either synthesis of CP or other glycopolymers in growing bacterial cells.

scholarly journals Suzuki Reaction for the Synthesis of New Derivatives of 4-Chloro-3,5-Dimethyl Phenol and their in vitro Antibacterial Screening

2019 ◽  
Vol 31 (12) ◽  
pp. 2955-2958
Author(s):  
R.H. Zaooli ◽  
F.A. Hussein ◽  
N.N.A. Jafar ◽  
S.N.K. Al-Thamir
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Elemental Analysis ◽  
Proteus Mirabilis ◽  
Suzuki Reaction ◽  
Antibacterial Properties ◽  
Antibacterial Screening ◽  
Derivatives Of ◽  
Dimethyl Phenol

Many derivatives of 4-chloro-3,5-dimethylphenol have been synthesized using Suzuki reaction and characterized by IR, 1H NMR and micro elemental analysis. These compounds also tested in terms of their antibacterial properties against Staphylococcus aureus, Escherichia coli and Proteus mirabilis.

scholarly journals Regulation of Staphylococcus aureus Capsular Polysaccharide Expression by agr and sarA

2002 ◽  
Vol 70 (2) ◽  
pp. 444-450 ◽  
Author(s):  
Thanh Luong ◽  
Subrata Sau ◽  
Marisa Gomez ◽  
Jean C. Lee ◽  
Chia Y. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Reporter Gene ◽  
Capsular Polysaccharide ◽  
Logarithmic Phase ◽  
Transcriptional Level ◽  
Slight Reduction ◽  
Mrna Synthesis ◽  
Global Regulators ◽  
In The Wild ◽  
Isogenic Mutants

ABSTRACT This study addresses the regulation of Staphylococcus aureus type 8 capsular polysaccharide (CP8) expression by the global regulators agr and sarA. We analyzed CP8 production, cap8-specific mRNA synthesis, and blaZ reporter gene activities of the transcriptional and translational fusions in strain Becker and its agr, sarA, and agr-sarA isogenic mutants during different phases of bacterial growth. In the wild-type strain, cap8 mRNA was undetectable until the mid-logarithmic phase of growth, whereas CP8 production was undetectable until 2 h later, at the onset of stationary phase. The delay most likely reflects the time needed for completing CP8 synthesis resulting from translation of cap8 mRNA. The agr mutation caused drastic reductions in CP8 production and cap8 gene transcription, suggesting that agr is a major positive regulator of CP8 expression. The results of gene fusion studies indicated that regulation by agr is exerted at the transcriptional level. In contrast, the sarA mutation caused only a slight reduction in cap8 mRNA synthesis and reporter gene activities. By comparing CP8 production and cap8 transcription, we observed that sarA affected CP8 production both trancriptionally and posttranslationally. We showed that agr was a major activator for cap gene expression not only in type 8 strain Becker but also in strains representing the four agr groups.

scholarly journals Comparative Opsonic and Protective Activities of Staphylococcus aureus Conjugate Vaccines Containing Native or Deacetylated Staphylococcal Poly-N-Acetyl-β-(1-6)-Glucosamine

2005 ◽  
Vol 73 (10) ◽  
pp. 6752-6762 ◽  
Author(s):  
Tomás Maira-Litrán ◽  
Andrea Kropec ◽  
Donald A. Goldmann ◽  
Gerald B. Pier
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Lethal Dose ◽  
Passive Immunization ◽  
Conjugate Vaccines ◽  
Specific Antibodies ◽  
Dose Dependent Fashion ◽  
Protective Antibodies ◽  
High Level

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis both synthesize the surface polysaccharide poly-N-acetyl-β-(1-6)-glucosamine (PNAG), which is produced in vitro with a high level (>90%) of the amino groups substituted by acetate. Here, we examined the role of the acetate substituents of PNAG in generating opsonic and protective antibodies. PNAG and a deacetylated form of the antigen (dPNAG; 15% acetylation) were conjugated to the carrier protein diphtheria toxoid (DT) and used to immunize animals. Mice responded in a dose-dependent fashion to both conjugate vaccines, with maximum antibody titers observed at the highest dose and 4 weeks after the last of three weekly immunizations. PNAG-DT and dPNAG-DT vaccines were also very immunogenic in rabbits. Antibodies raised to the conjugate vaccines in rabbits mediated the opsonic killing of various staphylococcal strains, but the specificity of the opsonic killing was primarily to dPNAG, as this antigen inhibited the killing of S. aureus strains by both PNAG- and dPNAG-specific antibodies. Passive immunization of mice with anti-dPNAG-DT rabbit sera showed significant levels of clearance of S. aureus from the blood (54 to 91%) compared to control mice immunized with normal rabbit sera, whereas PNAG-specific antibodies were ineffective at clearing S. aureus. Passive immunization of mice with a goat antiserum raised to the dPNAG-DT vaccine protected against a lethal dose of three different S. aureus strains. Overall, these data show that immunization of animals with a conjugate vaccine of dPNAG elicit antibodies that mediated opsonic killing and protected against S. aureus infection, including capsular polysaccharide types 5 and 8 and an untypable strain.

scholarly journals Transcriptional Induction of the Penicillin-Binding Protein 2 Gene in Staphylococcus aureus by Cell Wall-Active Antibiotics Oxacillin and Vancomycin

2003 ◽  
Vol 47 (3) ◽  
pp. 1028-1036 ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Shaohui Yin ◽  
Mamatha Challapalli ◽  
Robert S. Daum
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Growth Phase ◽  
Transcript Abundance ◽  
Promoter Sequence ◽  
Phase Variable ◽  
Penicillin Binding Protein ◽  
Promoter Regions ◽  
Putative Transcription Factor ◽  
Transcriptional Induction

ABSTRACT We found an increased abundance of pbpB-specific transcripts in vancomycin intermediate-resistant Staphylococcus aureus (VISA) isolates compared with that found in paired, genetically identical, susceptible isolates. This difference in expression cannot be explained by differences in the pbpB promoter sequence. Since the factors controlling pbpB gene expression have remained largely unexplored, various conditions that might affect pbpB transcript abundance were examined. In both vancomycin-susceptible and VISA strains, pbpB expression varied with the growth phase, with the highest abundance of pbpB-specific transcripts detected during mid-log phase. Interestingly, both vancomycin and oxacillin were able to induce pbpB transcription above a constitutive level. When vancomycin was absent, one of the three pbpB-specific transcripts that were usually faintly detected in non-VISA strains was more readily detected in VISA strains during mid-log but not stationary phase. This transcript was enhanced in non-VISA strains by vancomycin induction. Gel shift assays indicated that an increased amount of the putative transcription factor that binds to both P1 and P1′ promoter regions is present in the cytosol of vancomycin-induced cells. Neither the SigB sigma factor nor the quorum-sensing agr locus was required for growth phase-variable pbpB expression or transcriptional induction of pbpB by vancomycin or oxacillin. Also, MecI, MecR1, BlaI, and BlaR1, regulatory proteins that mediate β-lactam-inducible expression of mecA and β-lactamase, were not required for antibiotic induction of pbpB transcription. These data support the idea that pbpB expression is modulated by a trans-acting factor in response to the presence of the cell wall-active antibiotics vancomycin and oxacillin.

Effect of Thio- and Hydrazino-derivatives of Uracil, 6-Azauracil and 6-Azathymine on the Growth of Some Microorganisms in Vitro

1972 ◽  
Vol 27 (7) ◽  
pp. 818-821 ◽  
Author(s):  
Alexander Spassov ◽  
Evgeny Golovinsky ◽  
Nadejda Spassovska ◽  
Liliana Maneva
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antibacterial Activity ◽  
Bacillus Subtilis ◽  
Neurospora Crassa ◽  
Candida Tropicalis ◽  
Inhibitory Effect ◽  
Streptococcus Faecalis ◽  
Derivatives Of

The antibacterial activity of 2-thiouracil, 2-methylthiouracil, 2-hydrazinouracil, 2,4-dithiouracil, 2-thio-4-hydrazinouracil, 2-thio-6-azathymine, 2-hydrazino-6-azathymine, 2,4-dithio-6-azathymine, 2-thio-4-hydrazino-6-azathymine, 2,4-dimethylthio-6-azathymine, 2-methylthio-4-hydrazino-6-azathymine, 4-thio-6-azauracil and 4-hydrazino-6-azauracil has been studied on the growth of: Staphylococcus aureus 209, Streptococcus faecalis 775, Escherichiia coli 387, Pseudomonas aeruginosa, Bacillus subtilis, Candida tropicalis and Neurospora crassa 9863.The highest inhibitory effect was observed with 4-hydrazino-derivatives of 2-thiouracil, 6-azauracil and 2-thio-6-azathymine.

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