Mutations inpmrBconfer cross-resistance to the LptD inhibitor POL7080 and colistin inPseudomonas aeruginosa

Pseudomonas aeruginosais a major bacterial pathogen for which there is rising antibiotic resistance. We evaluated the resistance mechanisms ofP. aeruginosaagainst POL7080, a species-specific, first-in-class antibiotic in phase 3 clinical trials targeting the lipopolysaccharide transport protein LptD. We found resistance mutations in the two-component regulatorpmrB. Genome-wide transcriptomics and confocal microscopy studies together suggest that POL7080 is vulnerable to the same resistance mechanisms described previously for polymyxins, including colistin, that involve lipid A modifications to mitigate antibiotic cell surface binding.

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Mutations in pmrB Confer Cross-Resistance between the LptD Inhibitor POL7080 and Colistin in Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00511-19 ◽

2019 ◽

Vol 63 (9) ◽

Cited By ~ 6

Author(s):

Keith P. Romano ◽

Thulasi Warrier ◽

Bradley E. Poulsen ◽

Phuong H. Nguyen ◽

Alexander R. Loftis ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Resistance Mechanism ◽

Bacterial Pathogen ◽

Resistance Mechanisms ◽

Cross Resistance ◽

Surface Binding ◽

Content Type ◽

Cell Surface Binding ◽

Resistant Strains ◽

Species Specific

ABSTRACT Pseudomonas aeruginosa is a major bacterial pathogen associated with a rising prevalence of antibiotic resistance. We evaluated the resistance mechanisms of P. aeruginosa against POL7080, a species-specific, first-in-class antibiotic in clinical trials that targets the lipopolysaccharide transport protein LptD. We isolated a series of POL7080-resistant strains with mutations in the two-component sensor gene pmrB. Transcriptomic and confocal microscopy studies support a resistance mechanism shared with colistin, involving lipopolysaccharide modifications that mitigate antibiotic cell surface binding.

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Mutations that increase expression of the EmrAB-TolC efflux pump confer increased resistance to nitroxoline in Escherichia coli

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkz434 ◽

2019 ◽

Cited By ~ 1

Author(s):

Fabiola Puértolas-Balint ◽

Omar Warsi ◽

Marius Linkevicius ◽

Po-Cheng Tang ◽

Dan I Andersson

Keyword(s):

Escherichia Coli ◽

Target Genes ◽

Efflux Pump ◽

Resistance Mechanisms ◽

Cross Resistance ◽

Resistance Mutations ◽

Double Knockout ◽

Low Level ◽

Resistant Mutants ◽

Level Resistance

Abstract Objectives To determine the mechanism of resistance to the antibiotic nitroxoline in Escherichia coli. Methods Spontaneous nitroxoline-resistant mutants were selected at different concentrations of nitroxoline. WGS and strain reconstruction were used to define the genetic basis for the resistance. The mechanistic basis of resistance was determined by quantitative PCR (qPCR) and by overexpression of target genes. Fitness costs of the resistance mutations and cross-resistance to other antibiotics were also determined. Results Mutations in the transcriptional repressor emrR conferred low-level resistance to nitroxoline [nitroxoline MIC (MICNOX) = 16 mg/L] by increasing the expression of the emrA and emrB genes of the EmrAB-TolC efflux pump. These resistant mutants showed no fitness reduction and displayed cross-resistance to nalidixic acid. Second-step mutants with higher-level resistance (MICNOX = 32–64 mg/L) had mutations in the emrR gene, together with either a 50 kb amplification, a mutation in the gene marA, or an IS upstream of the lon gene. The latter mutations resulted in higher-level nitroxoline resistance due to increased expression of the tolC gene, which was confirmed by overexpressing tolC from an inducible plasmid in a low-level resistance mutant. Furthermore, the emrR mutations conferred a small increase in resistance to nitrofurantoin only when combined with an nfsAB double-knockout mutation. However, nitrofurantoin-resistant nfsAB mutants showed no cross-resistance to nitroxoline. Conclusions Mutations in different genes causing increased expression of the EmrAB-TolC pump lead to an increased resistance to nitroxoline. The structurally similar antibiotics nitroxoline and nitrofurantoin appear to have different modes of action and resistance mechanisms.

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Genome-wide chemical mutagenesis screens allow unbiased saturation of the cancer genome and identification of drug resistance mutations

10.1101/066555 ◽

2016 ◽

Cited By ~ 2

Author(s):

Jonathan S. Brammeld ◽

Mia Petljak ◽

Inigo Martincorena ◽

Steven P. Williams ◽

Luz Garcia Alonso ◽

...

Keyword(s):

Drug Resistance ◽

Point Mutations ◽

Gene Mutations ◽

Resistance Mechanisms ◽

Chemical Mutagenesis ◽

Specific Gene ◽

Drug Resistant ◽

Resistance Mutations ◽

Drug Resistance Mutations ◽

Genome Wide

AbstractDrug resistance is an almost inevitable consequence of cancer therapy and ultimately proves fatal for the majority of patients. In many cases this is the consequence of specific gene mutations that have the potential to be targeted to re-sensitize the tumor. The ability to uniformly saturate the genome with point mutations without chromosome or nucleotide sequence context bias would open the door to identify all putative drug resistance mutations in cancer models. Here we describe such a method for elucidating drug resistance mechanisms using genome-wide chemical mutagenesis allied to next-generation sequencing. We show that chemically mutagenizing the genome of cancer cells dramatically increases the number of drug-resistant clones and allows the detection of both known and novel drug resistance mutations. We have developed an efficient computational process that allows for the rapid identification of involved pathways and druggable targets. Such a priori knowledge would greatly empower serial monitoring strategies for drug resistance in the clinic as well as the development of trials for drug resistant patients.

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Bindin is essential for fertilization in the sea urchin

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2109636118 ◽

2021 ◽

Vol 118 (34) ◽

pp. e2109636118

Author(s):

Gary M. Wessel ◽

Yuuko Wada ◽

Mamiko Yajima ◽

Masato Kiyomoto

Keyword(s):

Cell Surface ◽

Sea Urchin ◽

Critical Role ◽

Egg Cell ◽

Surface Binding ◽

Broadcast Spawning ◽

Cell Surface Binding ◽

Insoluble Particles ◽

Males And Females ◽

Species Specific

Species-specific sperm−egg interactions are essential for sexual reproduction. Broadcast spawning of marine organisms is under particularly stringent conditions, since eggs released into the water column can be exposed to multiple different sperm. Bindin isolated from the sperm acrosome results in insoluble particles that cause homospecific eggs to aggregate, whereas no aggregation occurs with heterospecific eggs. Therefore, Bindin is concluded to play a critical role in fertilization, yet its function has never been tested. Here we report that Cas9-mediated inactivation of the bindin gene in a sea urchin results in perfectly normal-looking embryos, larvae, adults, and gametes in both males and females. What differed between the genotypes was that the bindin−/− sperm never fertilized an egg, functionally validating Bindin as an essential gamete interaction protein at the level of sperm–egg cell surface binding.

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Susceptibility of Colistin-Resistant, Gram-Negative Bacteria to Antimicrobial Peptides and Ceragenins

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00292-17 ◽

2017 ◽

Vol 61 (8) ◽

Cited By ~ 22

Author(s):

Marjan M. Hashemi ◽

John Rovig ◽

Scott Weber ◽

Brian Hilton ◽

Mehdi M. Forouzan ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

Antimicrobial Peptides ◽

Lipid A ◽

Resistance Mechanisms ◽

Clinical Isolates ◽

Cross Resistance ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Content Type

ABSTRACT The susceptibility of colistin-resistant clinical isolates of Klebsiella pneumoniae to ceragenins and antimicrobial peptides (AMPs) suggests that there is little to no cross-resistance between colistin and ceragenins/AMPs and that lipid A modifications are found in bacteria with modest changes in susceptibility to ceragenins and with high levels of resistance to colistin. These results suggest that there are differences in the resistance mechanisms to colistin and ceragenins/AMPs.

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Mutations in bdcA and valS correlate with quinolone resistance in wastewater Escherichia Coli

10.1101/2021.02.12.430739 ◽

2021 ◽

Author(s):

Negin Malekian ◽

Ali Al-Fatlawi ◽

Thomas U. Berendonk ◽

Michael Schroeder

Keyword(s):

Genome Wide Association Study ◽

A Priori ◽

Resistance Mechanisms ◽

Trna Synthetase ◽

Quinolone Resistance ◽

Resistance Mutations ◽

E Coli ◽

Genome Wide ◽

A Genome ◽

Biofilm Dispersal

AbstractSingle mutations can confer resistance to antibiotics. Identifying such mutations can help to develop and improve drugs. Here, we systematically screen for candidate quinolone resistance-conferring mutations. We sequenced highly diverse wastewater E. coli and performed a genome-wide association study (GWAS) correlating over 200,000 mutations against quinolone resistance phenotypes. We uncovered 13 statistically significant mutations including one located at the active site of the biofilm dispersal genes bdcA and six silent mutations in the aminoacyl-tRNA synthetase valS. The study also recovered the known mutations in the topoisomerases gyrA and parC.In summary, we demonstrate that GWAS effectively and comprehensively identifies resistance mutations without a priori knowledge of targets and mode of action. The results suggest that bdcA and valS may be novel resistance genes with biofilm dispersal and translation as novel resistance mechanisms.

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Emerging Transcriptional and Genomic Mechanisms Mediating Carbapenem and Polymyxin Resistance in Enterobacteriaceae: a Systematic Review of Current Reports

mSystems ◽

10.1128/msystems.00783-20 ◽

2020 ◽

Vol 5 (6) ◽

pp. e00783-20 ◽

Cited By ~ 1

Author(s):

Masego Mmatli ◽

Nontombi Marylucy Mbelle ◽

Nontuthuko E. Maningi ◽

John Osei Sekyere

Keyword(s):

Systematic Review ◽

Lipid A ◽

Transmembrane Protein ◽

Carbapenem Resistance ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Journal Articles ◽

Diverse Range ◽

Pubmed Database ◽

Species Specific

ABSTRACTThe spread of carbapenem- and polymyxin-resistant Enterobacteriaceae poses a significant threat to public health, challenging clinicians worldwide with limited therapeutic options. This review describes the current coding and noncoding genetic and transcriptional mechanisms mediating carbapenem and polymyxin resistance, respectively. A systematic review of all studies published in PubMed database between 2015 to October 2020 was performed. Journal articles evaluating carbapenem and polymyxin resistance mechanisms, respectively, were included. The search identified 171 journal articles for inclusion. Different New Delhi metallo-β-lactamase (NDM) carbapenemase variants had different transcriptional and affinity responses to different carbapenems. Mutations within the Klebsiella pneumoniae carbapenemase (KPC) mobile transposon, Tn4401, affect its promoter activity and expression levels, increasing carbapenem resistance. Insertion of IS26 in ardK increased imipenemase expression 53-fold. ompCF porin downregulation (mediated by envZ and ompR mutations), micCF small RNA hyperexpression, efflux upregulation (mediated by acrA, acrR, araC, marA, soxS, ramA, etc.), and mutations in acrAB-tolC mediated clinical carbapenem resistance when coupled with β-lactamase activity in a species-specific manner but not when acting without β-lactamases. Mutations in pmrAB, phoPQ, crrAB, and mgrB affect phosphorylation of lipid A of the lipopolysaccharide through the pmrHFIJKLM (arnBCDATEF or pbgP) cluster, leading to polymyxin resistance; mgrB inactivation also affected capsule structure. Mobile and induced mcr, efflux hyperexpression and porin downregulation, and Ecr transmembrane protein also conferred polymyxin resistance and heteroresistance. Carbapenem and polymyxin resistance is thus mediated by a diverse range of genetic and transcriptional mechanisms that are easily activated in an inducing environment. The molecular understanding of these emerging mechanisms can aid in developing new therapeutics for multidrug-resistant Enterobacteriaceae isolates.

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Mutations in bdcA and valS Correlate with Quinolone Resistance in Wastewater Escherichia coli

International Journal of Molecular Sciences ◽

10.3390/ijms22116063 ◽

2021 ◽

Vol 22 (11) ◽

pp. 6063

Author(s):

Negin Malekian ◽

Ali Al-Fatlawi ◽

Thomas U. Berendonk ◽

Michael Schroeder

Keyword(s):

Genome Wide Association Study ◽

A Priori ◽

Resistance Mechanisms ◽

Trna Synthetase ◽

Quinolone Resistance ◽

Resistance Mutations ◽

Topoisomerase Iv ◽

Genome Wide ◽

A Genome ◽

Biofilm Dispersal

Single mutations can confer resistance to antibiotics. Identifying such mutations can help to develop and improve drugs. Here, we systematically screen for candidate quinolone resistance-conferring mutations. We sequenced highly diverse wastewater E. coli and performed a genome-wide association study (GWAS) to determine associations between over 200,000 mutations and quinolone resistance phenotypes. We uncovered 13 statistically significant mutations including 1 located at the active site of the biofilm dispersal gene bdcA and 6 silent mutations in the aminoacyl-tRNA synthetase valS. The study also recovered the known mutations in the topoisomerases gyrase (gyrA) and topoisomerase IV (parC). In summary, we demonstrate that GWAS effectively and comprehensively identifies resistance mutations without a priori knowledge of targets and mode of action. The results suggest that mutations in the bdcA and valS genes, which are involved in biofilm dispersal and translation, may lead to novel resistance mechanisms.

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