scholarly journals MprF-Mediated Lysinylation of Phospholipids in Staphylococcus aureus Leads to Protection against Oxygen-Independent Neutrophil Killing

2003 ◽  
Vol 71 (1) ◽  
pp. 546-549 ◽  
Author(s):  
Sascha A. Kristian ◽  
Manuela Dürr ◽  
Jos A. G. Van Strijp ◽  
Birgid Neumeister ◽  
Andreas Peschel
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Peptides ◽  
Host Defense ◽  
Membrane Lipids ◽  
Human Monocytes ◽  
Wild Type ◽  
Cationic Antimicrobial Peptides ◽  
The Impact ◽  
Defense Molecules

ABSTRACT Staphylococcus aureus achieves resistance to defensins and similar cationic antimicrobial peptides (CAMPs) by modifying anionic membrane lipids via MprF with l-lysine, which leads to repulsion of these host defense molecules. S. aureus ΔmprF, which lacks the modification, was very efficiently killed by neutrophil defensins and CAMP-producing leukocytes, even when oxygen-dependent killing was disrupted, but was as susceptible as wild-type bacteria to inactivation by myeloperoxidase or human monocytes lacking defensins. These results demonstrate the impact and specificity of MprF-mediated CAMP resistance and underscore the role of defensin-like peptides in innate host defense.

scholarly journals In VitroCross-Resistance to Daptomycin and Host Defense Cationic Antimicrobial Peptides in Clinical Methicillin-Resistant Staphylococcus aureus Isolates

2011 ◽  
Vol 55 (9) ◽  
pp. 4012-4018 ◽  
Author(s):  
Nagendra N. Mishra ◽  
James McKinnell ◽  
Michael R. Yeaman ◽  
Aileen Rubio ◽  
Cynthia C. Nast ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cell Membrane ◽  
Antimicrobial Peptides ◽  
Surface Charge ◽  
Host Defense ◽  
Cationic Antimicrobial Peptides ◽  
Methicillin Resistant ◽  
Membrane Order

ABSTRACTWe investigated the hypothesis that methicillin-resistantStaphylococcus aureus(MRSA) isolates developing reduced susceptibilities to daptomycin (DAP; a calcium-dependent molecule acting as a cationic antimicrobial peptide [CAP]) may also coevolve reducedin vitrosusceptibilities to host defense cationic antimicrobial peptides (HDPs). Ten isogenic pairs of clinical MRSA DAP-susceptible/DAP-resistant (DAPs/DAPr) strains were tested against two distinct HDPs differing in structure, mechanism of action, and origin (thrombin-induced platelet microbicidal proteins [tPMPs] and human neutrophil peptide-1 [hNP-1]) and one bacterium-derived CAP, polymyxin B (PMB). Seven of 10 DAPrstrains had point mutations in themprFlocus (with or withoutyycoperon mutations), while three DAPrstrains had neither mutation. Several phenotypic parameters previously associated with DAPrwere also examined: cell membrane order (fluidity), surface charge, and cell wall thickness profiles. Compared to the 10 DAPsparental strains, their respective DAPrstrains exhibited (i) significantly reduced susceptibility to killing by all three peptides (P< 0.05), (ii) increased cell membrane fluidity, and (iii) significantly thicker cell walls (P< 0.0001). There was no consistent pattern of surface charge profiles distinguishing DAPsand DAPrstrain pairs. Reducedin vitrosusceptibility to two HDPs and one bacterium-derived CAP tracked closely with DAPrin these 10 recent MRSA clinical isolates. These results suggest that adaptive mechanisms involved in the evolution of DAPralso provide MRSA with enhanced survivability against HDPs. Such adaptations appear to correlate with MRSA variations in cell membrane order and cell wall structure. DAPrstrains with or without mutations in themprFlocus demonstrated significant cross-resistance profiles to these unrelated CAPs.

scholarly journals Similarities and differences between IL11 and IL11RA1 knockout mice for lung fibro-inflammation, fertility and craniosynostosis

2020 ◽  
Author(s):  
Benjamin Ng ◽  
Anissa A. Widjaja ◽  
Sivakumar Viswanathan ◽  
Jinrui Dong ◽  
Sonia P. Chothani ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Lung Fibroblasts ◽  
Loss Of Function ◽  
Wild Type ◽  
Reduced Body ◽  
Body Weights ◽  
Show Evidence ◽  
Similarities And Differences ◽  
The Impact

AbstractGenetic loss of function (LOF) in IL11RA infers IL11 signaling as important for fertility, fibrosis, inflammation and craniosynostosis. The impact of genetic LOF in IL11 has not been characterized. We generated IL11-knockout (Il11-/-) mice, which are born in normal Mendelian ratios, have normal hematological profiles and are protected from bleomycin-induced lung fibro-inflammation. Noticeably, baseline IL6 levels in the lungs of Il11-/- mice are lower than those of wild-type mice and are not induced by bleomycin damage, placing IL11 upstream of IL6. Lung fibroblasts from Il11-/- mice are resistant to pro-fibrotic stimulation and show evidence of reduced autocrine IL11 activity. Il11-/- female mice are infertile. Unlike Il11ra1-/- mice, Il11-/- mice do not have a craniosynostosis-like phenotype and exhibit mildly reduced body weights. These data highlight similarities and differences between LOF in IL11 or IL11RA while establishing further the role of IL11 signaling in fibrosis and stromal inflammation.

scholarly journals Antibacterial Peptides Resistance in Staphylococcus aureus: Various Mechanisms and the Association with Pathogenicity

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1527
Author(s):  
Miki Kawada-Matsuo ◽  
Mi Nguyen-Tra Le ◽  
Hitoshi Komatsuzawa
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Peptides ◽  
Antibacterial Peptides ◽  
Low Concentrations ◽  
Component Systems ◽  
Two Component Systems ◽  
Resistant Strains ◽  
Resistant Mutants ◽  
High Concentrations

Staphylococcus aureus is a bacterium that mainly colonizes the nasal cavity and skin. To colonize the host, it is necessary for S. aureus to resist many antibacterial factors derived from human and commensal bacteria. Among them are the bacteria-derived antimicrobial peptides (AMPs) called bacteriocins. It was reported that some two-component systems (TCSs), which are signal transduction systems specific to bacteria, are involved in the resistance to several bacteriocins in S. aureus. However, the TCS-mediated resistance is limited to relatively low concentrations of bacteriocins, while high concentrations of bacteriocins still exhibit antibacterial activity against S. aureus. To determine whether we could obtain highly bacteriocin-resistant mutants, we tried to isolate highly nisin A-resistant mutants by exposing the cells to sub-minimum inhibitory concentrations (MICs) of nisin A. Nisin A is one of the bacteriocins produced by Lactococcus lactis and is utilized as a food preservative worldwide. Finally, we obtained highly nisin A-resistant mutants with mutations in one TCS, BraRS, and in PmtR, which is involved in the expression of pmtABCD. Notably, some highly resistant strains also showed increased pathogenicity. Based on our findings, this review provides up-to-date information on the role of TCSs in the susceptibility to antibacterial peptides. Additionally, the mechanism for high antimicrobial peptides resistance and its association with pathogenicity in S. aureus is elucidated.

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 Engineering of the Pyruvate Dehydrogenase Bypass inSaccharomyces cerevisiae: Role of the Cytosolic Mg2+ and Mitochondrial K+ Acetaldehyde Dehydrogenases Ald6p and Ald4p in Acetate Formation during Alcoholic Fermentation

2000 ◽  
Vol 66 (8) ◽  
pp. 3151-3159 ◽  
Author(s):  
Fabienne Remize ◽  
Emilie Andrieu ◽  
Sylvie Dequin
Keyword(s):  
Carbon Flux ◽  
Alcoholic Fermentation ◽  
Pyruvate Decarboxylase ◽  
Wine Yeast ◽  
Wild Type ◽  
Acetate Production ◽  
Wine Yeast Strain ◽  
Acetate Formation ◽  
The Impact

ABSTRACT Acetic acid plays a crucial role in the organoleptic balance of many fermented products. We have investigated the factors controlling the production of acetate by Saccharomyces cerevisiaeduring alcoholic fermentation by metabolic engineering of the enzymatic steps involved in its formation and its utilization. The impact of reduced pyruvate decarboxylase (PDC), limited acetaldehyde dehydrogenase (ACDH), or increased acetoacetyl coenzyme A synthetase (ACS) levels in a strain derived from a wine yeast strain was studied during alcoholic fermentation. In the strain with the PDC1gene deleted exhibiting 25% of the PDC activity of the wild type, no significant differences were observed in the acetate yield or in the amounts of secondary metabolites formed. A strain overexpressingACS2 and displaying a four- to sevenfold increase in ACS activity did not produce reduced acetate levels. In contrast, strains with one or two disrupted copies of ALD6, encoding the cytosolic Mg2+-activated NADP-dependent ACDH and exhibiting 60 and 30% of wild-type ACDH activity, showed a substantial decrease in acetate yield (the acetate production was 75 and 40% of wild-type production, respectively). This decrease was associated with a rerouting of carbon flux towards the formation of glycerol, succinate, and butanediol. The deletion of ALD4, encoding the mitochondrial K+-activated NAD(P)-linked ACDH, had no effect on the amount of acetate formed. In contrast, a strain lacking both Ald6p and Ald4p exhibited a long delay in growth and acetate production, suggesting that Ald4p can partially replace the Ald6p isoform. Moreover, the ald6 ald4 double mutant was still able to ferment large amounts of sugar and to produce acetate, suggesting the contribution of another member(s) of the ALDfamily.

Role of the gut microbiota in airway immunity and host defense against respiratory infections

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Maike Willers ◽  
Dorothee Viemann
Keyword(s):  
Gut Microbiota ◽  
Host Defense ◽  
Gut Microbiome ◽  
Respiratory Infections ◽  
Current Knowledge ◽  
Viral Pathogens ◽  
Commensal Microbiota ◽  
Enhanced Resistance ◽  
The Impact

Abstract Colonization of the intestine with commensal bacteria is known to play a major role in the maintenance of human health. An altered gut microbiome is associated with various ensuing diseases including respiratory diseases. Here, we summarize current knowledge on the impact of the gut microbiota on airway immunity with a focus on consequences for the host defense against respiratory infections. Specific gut commensal microbiota compositions and functions are depicted that mediate protection against respiratory infections with bacterial and viral pathogens. Lastly, we highlight factors that have imprinting effects on the establishment of the gut microbiota early in life and are potentially relevant in the context of respiratory infections. Deepening our understanding of these relationships will allow to exploit the knowledge on how gut microbiome maturation needs to be modulated to ensure lifelong enhanced resistance towards respiratory infections.

scholarly journals Enhanced production of exopolysaccharide matrix and biofilm by a menadione-auxotrophic Staphylococcus aureus small-colony variant

2010 ◽  
Vol 59 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Rachna Singh ◽  
Pallab Ray ◽  
Anindita Das ◽  
Meera Sharma
Keyword(s):  
Staphylococcus Aureus ◽  
Tricarboxylic Acid Cycle ◽  
Surface Hydrophobicity ◽  
Tricarboxylic Acid ◽  
Polysaccharide Intercellular Adhesin ◽  
Wild Type ◽  
Small Colony Variant ◽  
Enhanced Production ◽  
Small Colony

The role of Staphylococcus aureus small-colony variants (SCVs) in the pathogenesis of biofilm-associated infections remains unclear. This study investigated the mechanism behind increased biofilm-forming potential of a menadione-auxotrophic Staphylococcus aureus SCV compared with the wild-type parental strain, as recently reported by our laboratory. SCVs displayed an autoaggregative phenotype, with a greater amount of polysaccharide intercellular adhesin (PIA), significantly reduced tricarboxylic acid cycle activity and a decreased susceptibility to aminoglycosides and cell-wall inhibitors compared with wild-type. The biofilms formed by the SCV were highly structured, consisting of large microcolonies separated by channels, and contained more biomass as well as significantly more PIA than wild-type biofilms. The surface hydrophobicity of the two phenotypes was similar. Thus, the autoaggregation and increased biofilm-forming capacity of menadione-auxotrophic Staphylococcus aureus SCVs in this study was related to the enhanced production of PIA in these variants.

Modulation of procaspase-7 self-activation by PEST amino acid residues of the N-terminal prodomain and intersubunit linker

2017 ◽  
Vol 95 (6) ◽  
pp. 634-643
Author(s):  
Juliano Alves ◽  
Miguel Garay-Malpartida ◽  
João M. Occhiucci ◽  
José E. Belizário
Keyword(s):  
Amino Acid ◽  
Large Subunit ◽  
Small Subunit ◽  
Cleavage Sites ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Caspase 7 ◽  
Caspase Family ◽  
The Impact

Procaspase-7 zymogen polypeptide is composed of a short prodomain, a large subunit (p20), and a small subunit (p10) connected to an intersubunit linker. Caspase-7 is activated by an initiator caspase-8 and -9, or by autocatalysis after specific cleavage at IQAD198↓S located at the intersubunit linker. Previously, we identified that PEST regions made of amino acid residues Pro (P), Glu (E), Asp (D), Ser (S), Thr (T), Asn (N), and Gln (Q) are conserved flanking amino acid residues in the cleavage sites within a prodomain and intersubunit linker of all caspase family members. Here we tested the impact of alanine substitution of PEST amino acid residues on procaspase-7 proteolytic self-activation directly in Escherichia coli. The p20 and p10 subunit cleavage were significantly delayed in double caspase-7 mutants in the prodomain (N18A/P26A) and intersubunit linker (S199A/P201A), compared with the wild-type caspase-7. The S199A/P201A mutants effectively inhibited the p10 small subunit cleavage. However, the mutations did not change the kinetic parameters (kcat/KM) and optimal tetrapeptide specificity (DEVD) of the purified mutant enzymes. The results suggest a role of PEST-amino acid residues in the molecular mechanism for prodomain and intersubunit cleavage and caspase-7 self-activation.

Deletion of OLFM4 Rescues Defective Host Defense Against Staphylococcus Aureus, but Not Aspergillus Fumigatus in Murine X-Linked Chronic Granulomatous Disease

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3276-3276
Author(s):  
Wenli Liu ◽  
Janyce A Sugui ◽  
Hongzhen Li ◽  
Kyung J Kwon-Chung ◽  
Griffin P. Rodgers
Keyword(s):  
Staphylococcus Aureus ◽  
Innate Immunity ◽  
Chronic Granulomatous Disease ◽  
Host Defense ◽  
Cathepsin G ◽  
Granulomatous Disease ◽  
Wild Type ◽  
Cathepsin C ◽  
Host Innate Immunity ◽  
Deficient Mice

Abstract Abstract 3276 Introduction: Chronic granulomatous disease (CGD) patients have recurrent life-threating bacterial and fungal infections due to the mutation of one of four subunits of the respiratory burst oxidase (NADPH-oxidase). Currently, the overall fatality rate in CGD patients remains high, making it necessary to better understand the basic biological processes governing host defense against bacteria and fungi in CGD. Olfactomedin 4 (OLFM4) is a neutrophil granule protein, which has been recently identified as a negative regulator of host innate immunity against bacteria infection in mice through modulation of neutrophil protease activity. The goal of this study was to evaluate the impact of OLFM4 deletion on host innate immunity against Staphylococcus aureus and Aspergillus fumigatus, two major pathogens encountered in CGD patients, in a murine X-linked CGD model. Results: We created gp91phox-and OLFM4-double deficient mice and investigated the mice defense against S. aureus and A. fumigatus infection. We found that neutrophil intracellular killing and in vivo clearance of S. aureus have been significantly increased in gp91phox- and OLFM4-double deficiency mice compared with CGD mice. The mice survival to S. aureus sepsis in gp91phox- and OLFM4-double deficiency mice has also been significantly prolonged compared with CGD mice. Our study has shown that the CGD mice immune deficiency against S. aureus has been totally corrected by additional loss of OLFM4 gene. To explore the mechanism that OLFM4 deletion rescued the bactericidal activities of CGD neutrophils, we analyzed cathepsin C and its downstream protease (neutrophil elastase and cathepsin G) activities in the mice neutrophils. Cathepsin C activities in OLFM4 deficient as well as double deficient mice neutrophils were significantly higher than those in WT mouse neutrophils. Cathepsin C activities in the neutrophils of CGD were similar to those in WT mice. Accordingly, the elastase and cathepsin G activities in the neutrophils of OLFM4 deficient and double deficient mice were also substantially higher than those in WT mice as well as CGD mice. However, we have not observed enhanced innate immunity against A. fumigatus in OLFM4 deficiency mice compared with wild-type mice using a lung infection model. The lung histopathology showed similar inflammation and fungal burden in the OLFM4 deficiency mice compared with wild-type mice. Correspondingly, mice survival to severe A. fumigatus infection did not show significant difference in gp91phox- and OLFM4-double deficiency mice compared with CGD mice, suggesting that OLFM4 may not play a role in mice host defense against A. fumigatus. Conclusion: 1. The damaged neutrophil bacterial killing and host innate immunity against S. aureus in CGD mice due to oxidative mechanism deficiency could be successfully rescued by deletion of OLFM4. 2. These results showed that the granule protease activities in CGD neutrophils could be substantially enhanced above the level in normal neutrophils by deletion of OLFM4, suggesting that the increased of serine proteinase activities due to OLFM4 deletion is NADPH-independent. 3. OLFM4 may not play a role in mice host defense against pulmonary A. fumigatus infection. 4. OLFM4 might prove to be an important target in CGD patients to augment host defense against bacterial infection. Disclosures: No relevant conflicts of interest to declare.

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