scholarly journals Growth-phase dependence of susceptibility to antimicrobial peptides in Staphylococcus aureus

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1786-1797 ◽  
Author(s):  
Miki Matsuo ◽  
Yuichi Oogai ◽  
Fuminori Kato ◽  
Motoyuki Sugai ◽  
Hitoshi Komatsuzawa
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Surface ◽  
Antimicrobial Peptides ◽  
Stationary Phase ◽  
Surface Charge ◽  
Growth Phase ◽  
Exponential Phase ◽  
Dependent Manner ◽  
Phase Dependence ◽  
Cell Surface Charge

Bacterial cell surface charge is responsible for susceptibility to cationic antimicrobial peptides. Previously, Staphylococcus aureus dlt and mprF were identified as factors conferring a positive charge upon cell surfaces. In this study, we investigated the regulation of cell surface charge during growth. Using a group of S. aureus MW2 mutants, which are gene-inactivated in 15 types of two-component systems (TCSs), we tested dltC and mprF expression and found that two TCSs, aps and agr, were associated with dltC and mprF expression in a growth phase-dependent manner. The first of these, aps, which had already been identified as a sensor of antimicrobial peptides and a positive regulator of dlt and mprF expression, was expressed strongly in the exponential phase, while its expression was significantly suppressed by agr in the stationary phase, resulting in higher expression of dltC and mprF in the exponential phase and lower expression in the stationary phase. Since both types of expression affected the cell surface charge, the susceptibility to antimicrobial peptides and cationic antibiotics was changed during growth. Furthermore, we found that the ability to sense antimicrobial peptides only functioned in the exponential phase. These results suggest that cell surface charge is tightly regulated during growth in S. aureus.

scholarly journals The Nature of Antibacterial Adaptive Immune Responses against Staphylococcus aureus Is Dependent on the Growth Phase and Extracellular Peptidoglycan

2019 ◽  
Vol 88 (1) ◽  
Author(s):  
Payal P. Balraadjsing ◽  
Lisbeth D. Lund ◽  
Yuri Souwer ◽  
Sebastian A. J. Zaat ◽  
Hanne Frøkiær ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
T Cell ◽  
Stationary Phase ◽  
Growth Phase ◽  
Cell Response ◽  
Th17 Cell ◽  
Exponential Phase ◽  
Th1 Cell ◽  
Content Type

ABSTRACT Staphylococcus aureus has evolved different strategies to evade the immune response, which play an important role in its pathogenesis. The bacteria express and shed various cell wall components and toxins during different stages of growth that may affect the protective T cell responses to extracellular and intracellular S. aureus. However, if and how the dendritic cell (DC)-mediated T cell response against S. aureus changes during growth of the bacterium remain elusive. In this study, we show that exponential-phase (EP) S. aureus bacteria were endocytosed very efficiently by human DCs, and these DCs strongly promoted production of the T cell polarizing factor interleukin-12 (IL-12). In contrast, stationary-phase (SP) S. aureus bacteria were endocytosed less efficiently by DCs, and these DCs produced small amounts of IL-12. The high level of IL-12 production induced by EP S. aureus led to the development of a T helper 1 (Th1) cell response, which was inhibited after neutralization of IL-12. Furthermore, preincubation with the staphylococcal cell wall component peptidoglycan (PGN), characteristically shed during the exponential growth phase, modulated the DC response to EP S. aureus. PGN preincubation appeared to inhibit IL-12p35 expression, leading to downregulation of IL-12 and an increase of IL-23 production by DCs, enhancing Th17 cell development. Taken together, our data indicate that exponential-phase S. aureus bacteria induce a stronger IL-12-dependent Th1 cell response than stationary-phase S. aureus and that this Th1 cell response shifted toward a Th17 cell response in the presence of PGN.

scholarly journals DaptomycinIn VitroActivity against Methicillin-Resistant Staphylococcus aureus Is Enhanced by d-Cycloserine in a Mechanism Associated with a Decrease in Cell Surface Charge

2013 ◽  
Vol 57 (9) ◽  
pp. 4537-4539 ◽  
Author(s):  
O. Gasch ◽  
S. K. Pillai ◽  
J. Dakos ◽  
S. Miyakis ◽  
R. C. Moellering ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Surface ◽  
Surface Charge ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Binding Assays ◽  
Methicillin Resistant ◽  
Content Type ◽  
Killing Activity ◽  
Cell Surface Charge ◽  
Mrsa Strains

ABSTRACTThe killing activity of daptomycin against an isogenic pair of daptomycin-susceptible and daptomycin-nonsusceptible (DNS) methicillin-resistantStaphylococcus aureus(MRSA) strains was enhanced by the addition of certain cell wall agents at 1× MIC. However, when high inocula of the DNS strain were used, no significant killing was observed in our experiments. Cytochromecbinding assays revealedd-cycloserine as the only agent associated with a reduction in the cell surface charge for both strains at the concentrations used.

scholarly journals Mapping Surface Charge Distribution of Single-Cell via Charged Nanoparticle

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1519
Author(s):  
Leixin Ouyang ◽  
Rubia Shaik ◽  
Ruiting Xu ◽  
Ge Zhang ◽  
Jiang Zhe
Keyword(s):  
Cell Surface ◽  
Charge Density ◽  
Surface Charge ◽  
Charge Distribution ◽  
Surface Charge Density ◽  
Single Cells ◽  
Fluorescent Light ◽  
Fluorescent Nanoparticles ◽  
Cell Surface Charge ◽  
Surface Charge Distribution

Many bio-functions of cells can be regulated by their surface charge characteristics. Mapping surface charge density in a single cell’s surface is vital to advance the understanding of cell behaviors. This article demonstrates a method of cell surface charge mapping via electrostatic cell–nanoparticle (NP) interactions. Fluorescent nanoparticles (NPs) were used as the marker to investigate single cells’ surface charge distribution. The nanoparticles with opposite charges were electrostatically bonded to the cell surface; a stack of fluorescence distribution on a cell’s surface at a series of vertical distances was imaged and analyzed. By establishing a relationship between fluorescent light intensity and number of nanoparticles, cells’ surface charge distribution was quantified from the fluorescence distribution. Two types of cells, human umbilical vein endothelial cells (HUVECs) and HeLa cells, were tested. From the measured surface charge density of a group of single cells, the average zeta potentials of the two types of cells were obtained, which are in good agreement with the standard electrophoretic light scattering measurement. This method can be used for rapid surface charge mapping of single particles or cells, and can advance cell-surface-charge characterization applications in many biomedical fields.

Bio-fabricated silver nanoparticles preferentially targets Gram positive depending on cell surface charge

2016 ◽  
Vol 83 ◽  
pp. 548-558 ◽  
Author(s):  
Debasis Mandal ◽  
Sandeep Kumar Dash ◽  
Balaram Das ◽  
Sourav Chattopadhyay ◽  
Totan Ghosh ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Cell Surface ◽  
Surface Charge ◽  
Gram Positive ◽  
Cell Surface Charge

Regulation of bacterial abstraction of lead by cell surface charge and chemical equilibria

Chemosphere ◽  
1980 ◽  
Vol 9 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Christopher L. Haber ◽  
Thomas G. Tornabene ◽  
R.K. Skogerboe
Keyword(s):  
Cell Surface ◽  
Surface Charge ◽  
Chemical Equilibria ◽  
Cell Surface Charge

scholarly journals RocA Regulates Phosphatase Activity of Virulence Sensor CovS of Group A Streptococcus in Growth Phase- and pH-Dependent Manners

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Chuan Chiang-Ni ◽  
He-Jing Chiou ◽  
Huei-Chuan Tseng ◽  
Chih-Yun Hsu ◽  
Cheng-Hsun Chiu
Keyword(s):  
Stationary Phase ◽  
Phosphatase Activity ◽  
Virulence Factor ◽  
Growth Phase ◽  
Exponential Phase ◽  
Acidic Stress ◽  
Phosphorylation Level ◽  
Factor Expression ◽  
Group A ◽  
Ph Dependent

ABSTRACT The control of the virulence response regulator and sensor (CovR-CovS) two-component regulatory system in group A Streptococcus (GAS) strains regulates more than 15% of gene expression and has critical roles in invasive GAS infection. The membrane-embedded CovS has kinase and phosphatase activities, and both are required for modulating the phosphorylation level of CovR. Regulator of Cov (RocA) is a positive regulator of covR and also been shown to be a pseudokinase that interacts with CovS to enhance the phosphorylation level of CovR; however, how RocA modulates the activity of CovS has not been determined conclusively. Although the phosphorylation level of CovR was decreased in the rocA mutant in the exponential phase, the present study shows that phosphorylated CovR in the rocA mutant increased to levels similar to those in the wild-type strain in the stationary phase of growth. In addition, acidic stress, which is generally present in the stationary phase, enhanced the phosphorylation level of CovR in the rocA mutant. The phosphorylation levels of CovR in the CovS phosphatase-inactivated mutant and its rocA mutant were similar under acidic stress and Mg2+ (the signal that inhibits CovS phosphatase activity) treatments, suggesting that the phosphatase activity, but not the kinase activity, of CovS is required for RocA to modulate CovR phosphorylation. The phosphorylation level of CovR is crucial for GAS strains to regulate virulence factor expression; therefore, the growth phase- and pH-dependent RocA activity would contribute significantly to GAS pathogenesis. IMPORTANCE The emergence of invasive group A streptococcal infections has been reported worldwide. Clinical isolates that have spontaneous mutations or a truncated allele of the rocA gene (e.g., emm3-type isolates) are considered to be more virulent than isolates with the intact rocA gene (e.g., emm1-type isolates). RocA is a positive regulator of covR and has been shown to enhance the phosphorylation level of intracellular CovR regulator through the functional CovS protein. CovS is the membrane-embedded sensor and modulates the phosphorylation level of CovR by its kinase and phosphatase activities. The present study shows that the enhancement of CovR phosphorylation is mediated via the repression of CovS’s phosphatase activity by RocA. In addition, we found that RocA acts dominantly on modulating CovR phosphorylation under neutral pH conditions and in the exponential phase of growth. The phosphorylation level of CovR is crucial for group A Streptococcus species to regulate virulence factor expression and is highly related to bacterial invasiveness; therefore, growth phase- and pH-dependent RocA activity and the sequence polymorphisms of rocA gene would contribute significantly to bacterial phenotype variations and pathogenesis.

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