The
            <i>msaABCR</i>
            Operon Regulates Resistance in Vancomycin-Intermediate Staphylococcus aureus Strains

Samanta, Dhritiman; Elasri, Mohamed O.

doi:10.1128/aac.03280-14

Cited by 15 publications

(48 citation statements)

References 73 publications

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“…We used a representative strain for each of the two clinically significant S. aureus capsule serotypes, CP5 and CP8: Mu50, a known vancomycin-intermediate S. aureus (VISA) isolate that produces capsule serotype 5; and UAMS-1, a vancomycin-sensitive S. aureus (VSSA) osteomyelitis isolate that produces capsule serotype 8. A restriction-deficient laboratory strain of S. aureus, RN4220, and the DH5a strain of Escherichia coli were used to move plasmid constructs into the strains of choice through transformation and phage transduction, as described elsewhere (Bae & Schneewind, 2006;Sahukhal & Elasri, 2014;Samanta & Elasri, 2014). S. aureus strains were grown on tryptic soy agar (TSA) or in tryptic soy broth (TSB).…”

Section: Methodsmentioning

confidence: 99%

“…The allelic replacement method was used to generate the msaABCR and msaB deletion mutants in strains Mu50 and UAMS-1 (Bae & Schneewind, 2006). For trans-complementation, the msaABCR region was cloned into the pCN34 low-copy vector with the modification of changing the kanamycin selectable marker to a chloramphenicolresistance marker as described elsewhere (Samanta & Elasri, 2014;Charpentier et al, 2004). The capsule mutant was generated by insertion of a transposon in the capA ORF.…”

Section: Methodsmentioning

confidence: 99%

“…This strain contains the bursa aurealis mariner-based erythromycin-resistance expression transposon within the encoding capA region. The mutation was moved by generalized transduction using bacteriophage W11 (Sambanthamoorthy et al, 2006;Samanta & Elasri, 2014). Introduction of the capA : : Tn mutation into the recipient strain was verified by PCR, sequencing and capsule production assay.…”

Section: Methodsmentioning

confidence: 99%

“…After the cells had grown to the appropriate phase, they were pelleted with centrifugation, treated with RNAprotect bacteria reagent (Qiagen), and stored at280 uC until analysis was carried out. The samples were thawed on ice and total RNA was extracted as previously described (Sahukhal & Elasri, 2014;Samanta & Elasri, 2014). qRT-PCR was performed and the relative fold change in gene expression was calculated using gyrA as the internal control (Goerke et al, 2000;Sahukhal & Elasri, 2014;Samanta & Elasri, 2014).…”

Section: Methodsmentioning

confidence: 99%

“…We previously identified the msaABCR operon, which is involved in the regulation of virulence, biofilm development and antibiotic resistance in S. aureus (Sambanthamoorthy et al, 2006(Sambanthamoorthy et al, , 2008Samanta & Elasri, 2014;Sahukhal & Elasri, 2014;Sahukhal et al, 2015). The deletion of the msaABCR operon alters the expression of several global regulators, including sarA, agr and sigB, all of which have been shown to be indirectly involved in capsule production (Bischoff et al, 2004;Pané-Farré et al, 2006;Meier et al, 2007;Dassy et al, 1993;Sahukhal & Elasri, 2014).…”

Section: Introductionmentioning

confidence: 99%

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MsaB activates capsule production at the transcription level in Staphylococcus aureus

2016

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Staphylococcus aureus produces several virulence factors that allow it to cause a variety of infections. One of the major virulence factors is the capsule, which contributes to the survival of the pathogen within the host as a way to escape phagocytosis. The production of the capsular polysaccharide is encoded in a 16 gene operon, which is regulated in response to several environmental stimuli including nutrient availability. For instance, the capsule is produced in the late-and post-exponential growth phases, but not in the early-or mid-exponential growth phase. Several regulators are involved in capsule production, but the regulation of the cap operon is still poorly understood. In this study, we show that MsaB activates the cap operon by binding directly to a 10 bp repeat in the promoter region. We show that despite the fact that MsaB is expressed throughout four growth phases, it only activates capsule production in the late-and post-exponential growth phases. Furthermore, we find that MsaB does not bind to its target site in the early and mid-exponential growth phases. This correlates with decreased nutrient availability and capsule production. These data suggest either that MsaB binding ability changes in response to nutrients or that other cap operon regulators interfere with the binding of MsaB to its target site. This study increases our understanding of the regulation of capsule production and the mechanism of action of MsaB.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MsaB activates capsule production at the transcription level in Staphylococcus aureus

2016

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Staphylococcal biofilm gene expression on biomaterials — A methodological study

Juhlin

Svensson

Thomsen

et al. 2017

J Biomedical Materials Res

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The combination of increased healthcare access, universal aging, and infallible therapy demands, synergistically drive the need for the development of biomaterial technologies that mitigate the challenge of biomaterial-associated infections (BAI). Staphylococcus epidermidis and Staphylococcus aureus account for the majority of BAI due to their ability to accumulate in adherent multilayered biofilm. This investigation details the development of gene expression assays to evaluate the genetic processes of attachment, accumulation, maturation, and dispersal phases of biofilms on biomaterials in vitro, while abiding by the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. The biofilm formation of S. epidermidis on polyurethane (PU) central venous catheters and S. aureus on machined titanium (Ti) was examined in terms of gene expression at early and late time points. The results provided insight into how each stage of biofilm formation is orchestrated over time on these biomaterials in vitro. Furthermore, the results suggested that mechanical RNA extraction, organic solvents, elimination of genomic DNA, and preamplification are advisable strategies to implement for biofilm gene expression analysis. It is concluded that this method can be employed for the assessment of biofilm-biomaterial interactions at the molecular level. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3400-3412, 2017.

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C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

Haunreiter

Tarnutzer

Bär

et al. 2023

Preprint

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Beta-lactam antibiotics are widely used to treat infections caused by the important human pathogen Staphylococcus aureus. Resistance to beta-lactams, as found in methicillin-resistant S. aureus (MRSA), renders effective treatment difficult. The second messenger cyclic di-3′,5′-adenosine monophosphate (c-di-AMP) promotes beta-lactam resistance in clinical S. aureus isolates. C-di-AMP plays a crucial role in the regulation of cellular processes such as virulence, cell wall homeostasis and resistance to beta-lactams in many bacterial species. In S. aureus, c-di-AMP synthesis is mediated by the diadenylate cyclase DacA, while its degradation is carried out by the phosphodiesterases GdpP and Pde2. In this work, we assessed the effect of altered c-di-AMP levels due to mutations in cacA, gdpP or gdpP/pde2 on virulence determinants. We report that a previously described growth defect in bacteria producing high c-di-AMP levels is mainly attributable to smaller cell size. High c-di-AMP levels also led to decreased survival upon oxidative stress, reduced production of the antioxidant staphyloxanthin, increased oxacillin and fosfomycin resistance and increased cell wall thickness. While resistance to ceftaroline was not affected, high c-di-AMP levels promoted tolerance to this antibiotic. In response to cell wall stress induced by antibiotics, the three-component regulatory system VraTSR mediates an increase in cell wall synthesis via the cell wall stress stimulon (CWSS). Increased c-di-AMP levels led to an activation of the CWSS. Upon deletion of vraR, resistance to oxacillin and fosfomycin as well as cell wall thickness diminished in the ΔgdpP mutant, indicating a contribution of the VraTSR system to the cell wall related phenotypes.

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The msaABCR Operon Regulates Resistance in Vancomycin-Intermediate Staphylococcus aureus Strains

Cited by 15 publications

References 73 publications

MsaB activates capsule production at the transcription level in Staphylococcus aureus

MsaB activates capsule production at the transcription level in Staphylococcus aureus

Staphylococcal biofilm gene expression on biomaterials — A methodological study

C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

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