scholarly journals Role for the phosphatidylinositol 3-phosphate 5-kinase in antifungal tolerance in Candida glabrata

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Rupinder Kaur
Keyword(s):  
Actin Cytoskeleton ◽  
Candida Glabrata ◽  
Actin Polymerization ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Ergosterol Biosynthesis ◽  
Multidrug Efflux Pump ◽  
Actin Organization ◽  
Opportunistic Fungal Pathogen ◽  
Phosphatidylinositol 3

Candida glabrata is an opportunistic fungal pathogen of humans, which is intrinsically less susceptible to widely used azole antifungals, that block ergosterol biosynthesis. The major azole resistance mechanisms include mitochondrial dysfunction and multidrug efflux pump overexpression. In the current study, we have uncovered an essential role for the actin cytoskeletal network reorganization in survival of the azole stress. We demonstrate for the first time that the azole antifungal fluconazole induces remodelling of the actin cytoskeleton in C. glabrata, and genetic or chemical perturbation of actin structures results in intracellular sterol accumulation and azole susceptibility. Further, we showed that the vacuolar membrane-resident phosphatidylinositol 3-phosphate 5-kinase (CgFab1) is pivotal to this process, as CgFAB1 disruption impaired vacuole homeostasis and actin organization. We also showed that the actin depolymerization factor CgCof1 binds to phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), and CgCof1 distribution along with the actin filament-capping protein CgCap2 is altered upon both CgFAB1disruption and fluconazole exposure. Additionally, while the F-actin-stabilizing compound jasplakinolide rescued azole toxicity in cytoskeleton defective-mutants, the actin polymerization inhibitor latrunculin B rendered fluconazole fully and partially fungicidal in azole-susceptible and azole-resistant C. glabrata clinical isolates, respectively. These data underscore the essentiality of actin cytoskeleton reorganization for azole stress survival. Lastly, we have also shown a pivotal role of CgFab1 kinase activity regulators, CgFig4, CgVac7 and CgVac14, through genetic analysis, in azole and echinocandin antifungal tolerance. Altogether, I shall present our findings on functions and metabolism of the PI(3,5)P2 lipid in antifungal tolerance and virulence of C. glabrata.

scholarly journals Efflux Pump Mediated Antimicrobial Resistance by Staphylococci in Health-Related Environments: Challenges and the Quest for Inhibition

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1502
Author(s):  
Abolfazl Dashtbani-Roozbehani ◽  
Melissa H. Brown
Keyword(s):  
Antimicrobial Resistance ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Current Knowledge ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Multidrug Efflux Pump ◽  
New Antibiotics ◽  
Efflux Pump Inhibitors

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

scholarly journals Set1-mediated histone H3K4 methylation is required for azole induction of the ergosterol biosynthesis genes and antifungal drug resistance in Candida glabrata.

2021 ◽  
Author(s):  
Kortany M Baker ◽  
Smriti Hoda ◽  
Debasmita Saha ◽  
Livia Georgescu ◽  
Nina D Serratore ◽  
...  
Keyword(s):  
Gene Expression ◽  
Drug Resistance ◽  
Candida Glabrata ◽  
Efflux Pump ◽  
Opportunistic Pathogen ◽  
Ergosterol Biosynthesis ◽  
H3k4 Methylation ◽  
Antifungal Drug Resistance ◽  
H3k4 Trimethylation ◽  
Histone H3k4

Candida glabrata is an opportunistic pathogen that has developed the ability to adapt and thrive under azole treated conditions. The common mechanisms that can result in Candida drug resistance are due to mutations or overexpression of the drug efflux pump or the target of azole drugs, Cdr1 and Erg11, respectively. However, the role of epigenetic histone modifications in azole-induced gene expression and drug resistance are poorly understood in C. glabrata. In this study, we show for the first time that Set1 mediates histone H3K4 mono-, di-, and trimethylation in C. glabrata. In addition, loss of SET1 and histone H3K4 methylation results in increased susceptibility to azole drugs in both C. glabrata and S. cerevisiae. Intriguingly, this increase in susceptibility to azole drugs in strains lacking Set1-mediated histone H3K4 methylation is not due to altered transcript levels of CDR1, PDR1 or Cdr1s ability to efflux drugs. Genome-wide transcript analysis revealed that Set1 is necessary for azole-induced expression of 12 genes involved in the late biosynthesis of ergosterol including ERG11 and ERG3. Importantly, chromatin immunoprecipitation analysis showed that histone H3K4 trimethylation was detected on chromatin of actively transcribed ERG genes. Furthermore, H3K4 trimethylation increased upon azole-induced gene expression which was also found to be dependent on the catalytic activity of Set1. Altogether, our findings show that Set1-mediated histone H3K4 methylation governs the intrinsic drug resistant status in C. glabrata via epigenetic control of azole-induced ERG gene expression.

scholarly journals Wsp1 Is Downstream of Cin1 and Regulates Vesicle Transport and Actin Cytoskeleton as an Effector of Cdc42 and Rac1 in Cryptococcus neoformans

2012 ◽  
Vol 11 (4) ◽  
pp. 471-481 ◽  
Author(s):  
Gui Shen ◽  
Erxun Zhou ◽  
J. Andrew Alspaugh ◽  
Ping Wang
Keyword(s):  
Actin Cytoskeleton ◽  
Cryptococcus Neoformans ◽  
Actin Polymerization ◽  
Fluorescent Protein ◽  
Rho Gtpase ◽  
Pathogenic Fungus ◽  
Vacuolar Membrane ◽  
Vesicle Transport ◽  
Content Type ◽  
Actin Organization

ABSTRACTHuman Wiskott-Aldrich syndrome protein (WASP) is a scaffold linking upstream signals to the actin cytoskeleton. In response to intersectin ITSN1 and Rho GTPase Cdc42, WASP activates the Arp2/3 complex to promote actin polymerization. The human pathogenCryptococcus neoformanscontains the ITSN1 homolog Cin1 and the WASP homolog Wsp1, which share more homology with human proteins than those of other fungi. Here we demonstrate that Cin1, Cdc42/Rac1, and Wsp1 function in an effector pathway similar to that of mammalian models. In thecin1mutant, expression of the autoactivated Wsp1-B-GBD allele partially suppressed the mutant defect in endocytosis, and expression of the constitutively activeCDC42Q61Lallele restored normal actin cytoskeleton structures. Similar phenotypic suppression can be obtained by the expression of a Cdc42-green fluorescent protein (GFP)-Wsp1 fusion protein. In addition, Rac1, which was found to exhibit a role in early endocytosis, activates Wsp1 to regulate vacuole fusion. Rac1 interacted with Wsp1 and depended on Wsp1 for its vacuolar membrane localization. Expression of the Wsp1-B-GBD allele restored vacuolar membrane fusion in therac1mutant. Collectively, our studies suggest novel ways in which this pathogenic fungus has adapted conserved signaling pathways to control vesicle transport and actin organization, likely benefiting survival within infected hosts.

scholarly journals Mechanisms Accounting for Fluoroquinolone Resistance in Escherichia coli Clinical Isolates

2008 ◽  
Vol 53 (1) ◽  
pp. 235-241 ◽  
Author(s):  
Sonia K. Morgan-Linnell ◽  
Lauren Becnel Boyd ◽  
David Steffen ◽  
Lynn Zechiedrich
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Multidrug Efflux Pump ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Genes Encoding

ABSTRACT Fluoroquinolone MICs are increased through the acquisition of chromosomal mutations in the genes encoding gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE), increased levels of the multidrug efflux pump AcrAB, and the plasmid-borne genes aac(6′)-Ib-cr and the qnr variants in Escherichia coli. In the accompanying report, we found that ciprofloxacin, gatifloxacin, levofloxacin, and norfloxacin MICs for fluoroquinolone-resistant E. coli clinical isolates were very high and widely varied (L. Becnel Boyd, M. J. Maynard, S. K. Morgan-Linnell, L. B. Horton, R. Sucgang, R. J. Hamill, J. Rojo Jimenez, J. Versalovic, D. Steffen, and L. Zechiedrich, Antimicrob. Agents Chemother. 53:229-234, 2009). Here, we sequenced gyrA, gyrB, parC, and parE; screened for aac(6′)-Ib-cr and qnrA; and quantified AcrA levels in E. coli isolates for which patient sex, age, location, and site of infection were known. We found that (i) all fluoroquinolone-resistant isolates had gyrA mutations; (ii) ∼85% of gyrA mutants also had parC mutations; (iii) the ciprofloxacin and norfloxacin MICs for isolates harboring aac(6′)-Ib-cr (∼23%) were significantly higher, but the gatifloxacin and levofloxacin MICs were not; (iv) no isolate had qnrA; and (v) ∼33% of the fluoroquinolone-resistant isolates had increased AcrA levels. Increased AcrA correlated with nonsusceptibility to the fluoroquinolones but did not correlate with nonsusceptibility to any other antimicrobial agents reported from hospital antibiograms. Known mechanisms accounted for the fluoroquinolone MICs of 50 to 70% of the isolates; the remaining included isolates for which the MICs were up to 1,500-fold higher than expected. Thus, additional, unknown fluoroquinolone resistance mechanisms must be present in some clinical isolates.

Topoisomerase mutations and efflux are associated with fluoroquinolone resistance in Enterococcus faecalis

2006 ◽  
Vol 55 (10) ◽  
pp. 1395-1401 ◽  
Author(s):  
Yoshihiro Oyamada ◽  
Hideaki Ito ◽  
Matsuhisa Inoue ◽  
Jun-ichi Yamagishi
Keyword(s):  
Enterococcus Faecalis ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Fluoroquinolone Resistance ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Topoisomerase Iv ◽  
Gram Positive Bacteria ◽  
Efflux Pump Inhibitors ◽  
Resistant Mutants

To understand better the mechanisms of fluoroquinolone resistance in Enterococcus faecalis, fluoroquinolone-resistant mutants isolated from Ent. faecalis ATCC 29212 by stepwise selection with sparfloxacin (SPX) and norfloxacin (NOR) were analysed. The results showed the following. (i) In general, fluoroquinolone-resistance mechanisms in Ent. faecalis are similar to those in other Gram-positive bacteria, such as Staphylococcus aureus and Streptococcus pneumoniae, namely, mutants with amino acid changes in both GyrA and ParC exhibited high fluoroquinolone resistance, and single GyrA mutants and a single ParC mutant were more resistant to SPX and NOR, respectively, than the parent strain, indicating that the primary targets of SPX and NOR in Ent. faecalis are DNA gyrase and topoisomerase IV, respectively. (ii) Alterations in GyrB (ΔKGA, residues 395–397) and ParE (Glu-459 to Lys) were associated with fluoroquinolone resistance in some mutants. Moreover, the facts that the NOR MIC, but not the SPX MIC, decreased in the presence of multidrug efflux pump inhibitors, that NOR accumulation decreased in the cells, and that the EmeA mRNA expression level did not change, strongly suggested that a NorA-like efflux pump, rather than EmeA, was involved in resistance to NOR.

scholarly journals Post-Covid-19 Era: What is Next?

2021 ◽  
Author(s):  
Shiela Chetri
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antimicrobial Resistance ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Multidrug Efflux Pump ◽  
High Risk Factors ◽  
Clinical Complications

Antimicrobial resistance (AMR) is a natural phenomenon in bacteria which becomes a threat for health-care settings around the world. A concerted global response is needed to tackle rising rates of antibiotic resistance, without it we risk returning to the pre antibiotic era. As bacteria evolve very fast according to the environment in which they inhabit via developing different defence mechanisms to combat with the noxious agents like different classes of antibiotics including carbapenems. This results into treatment failure and clinical complications. Global emergence of antibiotic resistance due to bacterial multidrug efflux pump systems are a major and common mechanism of intrinsic antimicrobial resistance employed by bacteria which are spreading rapidly due to over use or misuse of antimicrobial agents. This review mainly focusses on the transcriptional expression of efflux pump system AcrAB-TolC, local regulatory genes (AcrR and AcrS), mediating carbapenem resistance in clinical isolates of Escherichia coli under antibiotic stress, a genetic interplay study between intrinsic and acquired antibiotic resistance mechanisms along with a brief summary on high risk factors and prevalence of urinary tract infections by multidrug resistant Uropathogenic Escherichia coli.

scholarly journals Fluconazole-induced actin cytoskeleton remodeling requires phosphatidylinositol 3-phosphate 5-kinase in the pathogenic yeast Candida glabrata

2018 ◽  
Vol 110 (3) ◽  
pp. 425-443 ◽  
Author(s):  
Priyanka Bhakt ◽  
Raju Shivarathri ◽  
Deepak Kumar Choudhary ◽  
Sapan Borah ◽  
Rupinder Kaur
Keyword(s):  
Actin Cytoskeleton ◽  
Candida Glabrata ◽  
Pathogenic Yeast ◽  
Cytoskeleton Remodeling ◽  
Phosphatidylinositol 3

scholarly journals Structural Features Governing the Activity of Lactoferricin-Derived Peptides That Act in Synergy with Antibiotics againstPseudomonas aeruginosa In VitroandIn Vivo

2010 ◽  
Vol 55 (1) ◽  
pp. 218-228 ◽  
Author(s):  
Susana Sánchez-Gómez ◽  
Bostjan Japelj ◽  
Roman Jerala ◽  
Ignacio Moriyón ◽  
Mirian Fernández Alonso ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Concomitant Administration ◽  
Structural Features ◽  
Antimicrobial Activities ◽  
Resistance Mechanisms ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Relationship Analysis ◽  
Lethal Infection

ABSTRACTPseudomonas aeruginosais naturally resistant to many antibiotics, and infections caused by this organism are a serious threat, especially to hospitalized patients. The intrinsic low permeability ofP. aeruginosato antibiotics results from the coordinated action of several mechanisms, such as the presence of restrictive porins and the expression of multidrug efflux pump systems. Our goal was to develop antimicrobial peptides with an improved bacterial membrane-permeabilizing ability, so that they enhance the antibacterial activity of antibiotics. We carried out a structure activity relationship analysis to investigate the parameters that govern the permeabilizing activity of short (8- to 12-amino-acid) lactoferricin-derived peptides. We used a new class of constitutional and sequence-dependent descriptors called PEDES (peptidedescriptors fromsequence) that allowed us to predict (Spearman's ρ = 0.74;P< 0.001) the permeabilizing activity of a new peptide generation. To study if peptide-mediated permeabilization could neutralize antibiotic resistance mechanisms, the most potent peptides were combined with antibiotics, and the antimicrobial activities of the combinations were determined onP. aeruginosastrains whose mechanisms of resistance to those antibiotics had been previously characterized. A subinhibitory concentration of compound P2-15 or P2-27 sensitizedP. aeruginosato most classes of antibiotics tested and counteracted several mechanisms of antibiotic resistance, including loss of the OprD porin and overexpression of several multidrug efflux pump systems. Using a mouse model of lethal infection, we demonstrated that whereas P2-15 and erythromycin were unable to protect mice when administered separately, concomitant administration of the compounds afforded long-lasting protection to one-third of the animals.

scholarly journals Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

2016 ◽  
Vol 198 (23) ◽  
pp. 3200-3208 ◽  
Author(s):  
Etsuko Sugawara ◽  
Seiji Kojima ◽  
Hiroshi Nikaido
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Fourth Generation ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Content Type

ABSTRACTKlebsiella pneumoniae, one of the most important nosocomial pathogens, is becoming a major problem in health care because of its resistance to multiple antibiotics, including cephalosporins of the latest generation and, more recently, even carbapenems. This is largely due to the spread of plasmid-encoded extended-spectrum β-lactamases. However, antimicrobial agents must first penetrate the outer membrane barrier in order to reach their targets, and hydrophilic and charged β-lactams presumably diffuse through the porin channels. Unfortunately, the properties ofK. pneumoniaeporin channels are largely unknown. In this study, we made clean deletions ofK. pneumoniaeporin genesompK35andompK36and examined the antibiotic susceptibilities and diffusion rates of β-lactams. The results showed that OmpK35 and OmpK36 produced larger more permeable channels than theirEscherichia colihomologs OmpF and OmpC; OmpK35 especially produced a diffusion channel of remarkably high permeability toward lipophilic (benzylpenicillin) and large (cefepime) compounds. These results were also confirmed by expressing various porins in anE. colistrain lacking major porins and the major multidrug efflux pump AcrAB. Our data explain why the development of drug resistance inK. pneumoniaeis so often accompanied by the mutational loss of its porins, especially OmpK35, in addition to the various plasmid-carried genes of antibiotic resistance, because even hydrolysis by β-lactamases becomes inefficient in producing high levels of resistance if the bacterium continues to allow a rapid influx of β-lactams through its wide porin channels.IMPORTANCEIn Gram-negative bacteria, drugs must first enter the outer membrane, usually through porin channels. Thus, the quantitative examination of influx rates is essential for the assessment of resistance mechanisms, yet no such studies exist for a very important nosocomial pathogen,Klebsiella pneumoniae. We found that the larger channel porin of this organism, OmpK35, produces a significantly larger channel than itsEscherichia colihomolog, OmpF. This makes unmodifiedK. pneumoniaestrains more susceptible to relatively large antibiotics, such as the third- and fourth-generation cephalosporins. Also, even the acquisition of powerful β-lactamases is not likely to make them fully resistant in the presence of such an effective influx process, explaining why so many clinical isolates of this organism lack porins.

scholarly journals Pivotal Role for a Tail Subunit of the RNA Polymerase II Mediator Complex CgMed2 in Azole Tolerance and Adherence in Candida glabrata

2014 ◽  
Vol 58 (10) ◽  
pp. 5976-5986 ◽  
Author(s):  
Sapan Borah ◽  
Raju Shivarathri ◽  
Vivek Kumar Srivastava ◽  
Sélène Ferrari ◽  
Dominique Sanglard ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Candida Glabrata ◽  
Efflux Pump ◽  
Antifungal Drugs ◽  
Pivotal Role ◽  
Mediator Complex ◽  
Multidrug Efflux Pump ◽  
Content Type ◽  
Azole Antifungals

ABSTRACTAntifungal therapy failure can be associated with increased resistance to the employed antifungal agents.Candida glabrata, the second most common cause of invasive candidiasis, is intrinsically less susceptible to the azole class of antifungals and accounts for 15% of allCandidabloodstream infections. Here, we show thatC. glabrataMED2(CgMED2), which codes for a tail subunit of the RNA polymerase II Mediator complex, is required for resistance to azole antifungal drugs inC. glabrata. An inability to transcriptionally activate genes encoding a zinc finger transcriptional factor, CgPdr1, and multidrug efflux pump, CgCdr1, primarily contributes to the elevated susceptibility of theCgmed2Δ mutant toward azole antifungals. We also report for the first time that theCgmed2Δ mutant exhibits sensitivity to caspofungin, a constitutively activated protein kinase C-mediated cell wall integrity pathway, and elevated adherence to epithelial cells. The increased adherence of theCgmed2Δ mutant was attributed to the elevated expression of theEPA1andEPA7genes. Further, our data demonstrate thatCgMED2is required for intracellular proliferation in human macrophages and modulates survival in a murine model of disseminated candidiasis. Lastly, we show an essential requirement for CgMed2, along with the Mediator middle subunit CgNut1 and the Mediator cyclin-dependent kinase/cyclin subunit CgSrb8, for the high-level fluconazole resistance conferred by the hyperactive allele of CgPdr1. Together, our findings underscore a pivotal role for CgMed2 in basal tolerance and acquired resistance to azole antifungals.

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