scholarly journals Importance of Polyphosphate Kinase 1 for Campylobacter jejuni Viable-but-Nonculturable Cell Formation, Natural Transformation, and Antimicrobial Resistance

2009 ◽  
Vol 75 (24) ◽  
pp. 7838-7849 ◽  
Author(s):  
Dharanesh Gangaiah ◽  
Issmat I. Kassem ◽  
Zhe Liu ◽  
Gireesh Rajashekara
Keyword(s):  
Antimicrobial Resistance ◽  
Campylobacter Jejuni ◽  
Stress Responses ◽  
Natural Transformation ◽  
Cell Formation ◽  
Acid Stress ◽  
Therapeutic Interventions ◽  
Wild Type ◽  
Viable But Nonculturable ◽  
Stress Survival

ABSTRACT Campylobacter jejuni, a gram-negative, microaerophilic bacterium, is a predominant cause of bacterial gastroenteritis in humans. Although considered fragile and fastidious and lacking many classical stress response mechanisms, C. jejuni exhibits a remarkable capacity for survival and adaptation, successfully infecting humans and persisting in the environment. Consequently, understanding the physiological and genetic properties that allow C. jejuni to survive and adapt to various stress conditions is crucial for therapeutic interventions. Of importance is polyphosphate (poly-P) kinase 1 (PPK1), which is a key enzyme mediating the synthesis of poly-P, an essential molecule for survival, mediating stress responses, host colonization, and virulence in many bacteria. Therefore, we investigated the role of PPK1 in C. jejuni pathogenesis, stress survival, and adaptation. Our findings demonstrate that a C. jejuni Δppk1 mutant was deficient in poly-P accumulation, which was associated with a decreased ability to form viable-but-nonculturable cells under acid stress. The Δppk1 mutant also showed a decreased frequency of natural transformation and an increased susceptibility to various antimicrobials. Furthermore, the Δppk1 mutant was characterized by a dose-dependent deficiency in chicken colonization. Complementation of the Δppk1 mutant with the wild-type copy of ppk1 restored the deficient phenotypes to levels similar to those of the wild type. Our results suggest that poly-P plays an important role in stress survival and adaptation and might contribute to genome plasticity and the spread and development of antimicrobial resistance in C. jejuni. These findings highlight the potential of PPK1 as a novel target for therapeutic interventions.

scholarly journals Beyond Antimicrobial Resistance: Evidence for a Distinct Role of the AcrD Efflux Pump inSalmonellaBiology

mBio ◽  
2016 ◽  
Vol 7 (6) ◽  
Author(s):  
Michelle M. C. Buckner ◽  
Jessica M. A. Blair ◽  
Roberto M. La Ragione ◽  
Jane Newcombe ◽  
Daniel J. Dwyer ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Stress Responses ◽  
Salmonella Enterica ◽  
Efflux Pump ◽  
Tricarboxylic Acid Cycle ◽  
Efflux Pumps ◽  
Wild Type ◽  
Swarming Motility ◽  
Serovar Typhimurium

ABSTRACTFor over 20 years, bacterial multidrug resistance (MDR) efflux pumps have been studied because of their impact on resistance to antimicrobials. However, critical questions remain, including why produce efflux pumps under non-antimicrobial treatment conditions, and why have multiple pumps if their only purpose is antimicrobial efflux?Salmonellaspp. possess five efflux pump families, including the resistance-nodulation-division (RND) efflux pumps. Notably, the RND efflux pump AcrD has a unique substrate profile, distinct from otherSalmonellaefflux pumps. Here we show that inactivation ofacrDresults in a profoundly altered transcriptome and modulation of pathways integral toSalmonellabiology. The most significant transcriptome changes were central metabolism related, with additional changes observed in pathogenicity, environmental sensing, and stress response pathway expression. The extent of tricarboxylic acid cycle and fumarate metabolism expression changes led us to hypothesize thatacrDinactivation may result in motility defects due to perturbation of metabolite concentrations, such as fumarate, for which a role in motility has been established. Despite minimal detectable changes in flagellar gene expression, we found that anacrDmutantSalmonella entericaserovar Typhimurium isolate was significantly impaired for swarming motility, which was restored by addition of fumarate. TheacrDmutant outcompeted the wild type in fitness experiments. The results of these diverse experiments provide strong evidence that the AcrD efflux pump is not simply a redundant system providing response resilience, but also has distinct physiological functions. Together, these data indicate that the AcrD efflux pump has a significant and previously underappreciated impact on bacterial biology, despite only minor perturbations of antibiotic resistance profiles.IMPORTANCEEfflux pumps in Gram-negative bacteria are studied because of their important contributions to antimicrobial resistance. However, the role of these pumps in bacterial biology has remained surprisingly elusive. Here, we provide evidence that loss of the AcrD efflux pump significantly impacts the physiology ofSalmonella entericaserovar Typhimurium. Inactivation ofacrDled to changes in the expression of 403 genes involved in fundamental processes, including basic metabolism, virulence, and stress responses. Pathways such as these allowSalmonellato grow, survive in the environment, and cause disease. Indeed, our data show that theacrDmutant is more fit than wild-typeSalmonellaunder standard lab conditions. We hypothesized that inactivation ofacrDwould alter levels of bacterial metabolites, impacting traits such as swarming motility. We demonstrated this by exogenous addition of the metabolite fumarate, which partially restored theacrDmutant’s swarming defect. This work extends our understanding of the role of bacterial efflux pumps.

scholarly journals InsP7is a small-molecule regulator of NUDT3-mediated mRNA decapping and processing-body dynamics

2020 ◽  
Vol 117 (32) ◽  
pp. 19245-19253 ◽  
Author(s):  
Soumyadip Sahu ◽  
Zhenzhen Wang ◽  
Xinfu Jiao ◽  
Chunfang Gu ◽  
Nikolaus Jork ◽  
...  
Keyword(s):  
Stress Responses ◽  
Messenger Rna ◽  
Control Process ◽  
Stem Cell Differentiation ◽  
Wild Type ◽  
Inositol Pyrophosphate ◽  
Body Dynamics ◽  
Processing Body ◽  
The Stability

Regulation of enzymatic 5′ decapping of messenger RNA (mRNA), which normally commits transcripts to their destruction, has the capacity to dynamically reshape the transcriptome. For example, protection from 5′ decapping promotes accumulation of mRNAs into processing (P) bodies—membraneless, biomolecular condensates. Such compartmentalization of mRNAs temporarily removes them from the translatable pool; these repressed transcripts are stabilized and stored until P-body dissolution permits transcript reentry into the cytosol. Here, we describe regulation of mRNA stability and P-body dynamics by the inositol pyrophosphate signaling molecule 5-InsP7(5-diphosphoinositol pentakisphosphate). First, we demonstrate 5-InsP7inhibits decapping by recombinant NUDT3 (Nudix [nucleoside diphosphate linked moiety X]-type hydrolase 3) in vitro. Next, in intact HEK293 and HCT116 cells, we monitored the stability of a cadre of NUDT3 mRNA substrates following CRISPR-Cas9 knockout ofPPIP5Ks(diphosphoinositol pentakisphosphate 5-kinases type 1 and 2, i.e.,PPIP5KKO), which elevates cellular 5-InsP7levels by two- to threefold (i.e., within the physiological rheostatic range). ThePPIP5KKO cells exhibited elevated levels of NUDT3 mRNA substrates and increased P-body abundance. Pharmacological and genetic attenuation of 5-InsP7synthesis in the KO background reverted both NUDT3 mRNA substrate levels and P-body counts to those of wild-type cells. Furthermore, liposomal delivery of a metabolically resistant 5-InsP7analog into wild-type cells elevated levels of NUDT3 mRNA substrates and raised P-body abundance. In the context that cellular 5-InsP7levels normally fluctuate in response to changes in the bioenergetic environment, regulation of mRNA structure by this inositol pyrophosphate represents an epitranscriptomic control process. The associated impact on P-body dynamics has relevance to regulation of stem cell differentiation, stress responses, and, potentially, amelioration of neurodegenerative diseases and aging.

scholarly journals Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 286
Author(s):  
Mary Frances Nakamya ◽  
Moses B. Ayoola ◽  
Leslie A. Shack ◽  
Mirghani Mohamed ◽  
Edwin Swiatlo ◽  
...  
Keyword(s):  
Stress Responses ◽  
Critical Role ◽  
Acid Stress ◽  
Arginine Decarboxylase ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Opportunistic Human Pathogen ◽  
Thiol Peroxidase ◽  
The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

scholarly journals Whole genome-based characterisation of antimicrobial resistance and genetic diversity in Campylobacter jejuni and Campylobacter coli from ruminants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Medelin Ocejo ◽  
Beatriz Oporto ◽  
José Luis Lavín ◽  
Ana Hurtado
Keyword(s):  
Genetic Diversity ◽  
Antimicrobial Resistance ◽  
Campylobacter Jejuni ◽  
Resistance Genes ◽  
Campylobacter Coli ◽  
Whole Genome ◽  
Northern Spain ◽  
Sequence Alignments ◽  
Phenotypic Data ◽  
Wide Range

AbstractCampylobacter, a leading cause of gastroenteritis in humans, asymptomatically colonises the intestinal tract of a wide range of animals.Although antimicrobial treatment is restricted to severe cases, the increase of antimicrobial resistance (AMR) is a concern. Considering the significant contribution of ruminants as reservoirs of resistant Campylobacter, Illumina whole-genome sequencing was used to characterise the mechanisms of AMR in Campylobacter jejuni and Campylobacter coli recovered from beef cattle, dairy cattle, and sheep in northern Spain. Genome analysis showed extensive genetic diversity that clearly separated both species. Resistance genotypes were identified by screening assembled sequences with BLASTn and ABRicate, and additional sequence alignments were performed to search for frameshift mutations and gene modifications. A high correlation was observed between phenotypic resistance to a given antimicrobial and the presence of the corresponding known resistance genes. Detailed sequence analysis allowed us to detect the recently described mosaic tet(O/M/O) gene in one C. coli, describe possible new alleles of blaOXA-61-like genes, and decipher the genetic context of aminoglycoside resistance genes, as well as the plasmid/chromosomal location of the different AMR genes and their implication for resistance spread. Updated resistance gene databases and detailed analysis of the matched open reading frames are needed to avoid errors when using WGS-based analysis pipelines for AMR detection in the absence of phenotypic data.

scholarly journals Roles of rpoN, fliA,and flgR in Expression of Flagella inCampylobacter jejuni

2001 ◽  
Vol 183 (9) ◽  
pp. 2937-2942 ◽  
Author(s):  
Aparna Jagannathan ◽  
Chrystala Constantinidou ◽  
Charles W. Penn
Keyword(s):  
Campylobacter Jejuni ◽  
Genome Sequence ◽  
Sigma Factor ◽  
Transcriptional Activator ◽  
Alternative Sigma Factor ◽  
Wild Type ◽  
Electron Microscopic ◽  
Global Regulation ◽  
Mutant Strains ◽  
Microscopic Studies

ABSTRACT Three potential regulators of flagellar expression present in the genome sequence of Campylobacter jejuni NCTC 11168, the genes rpoN, flgR, andfliA, which encode the alternative sigma factor ς54, the ς54-associated transcriptional activator FlgR, and the flagellar sigma factor ς28, respectively, were investigated for their role in global regulation of flagellar expression. The three genes were insertionally inactivated inC. jejuni strains NCTC 11168 and NCTC 11828. Electron microscopic studies of the wild-type and mutant strains showed that therpoN and flgR mutants were nonflagellate and that the fliA mutant had truncated flagella. Immunoblotting experiments with the three mutants confirmed the roles of rpoN, flgR, and fliA in the expression of flagellin.

Abstract 356: IKK-Beta Deletion Alleviates the Atherogenetic Effect of Intermittent Hypoxia Induced Macrophage Foam Cell Formation

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Toshihiro Imamura ◽  
Iain S Hartley ◽  
Abdull J Massri ◽  
Orit Poulsen ◽  
Dan Zhou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Intermittent Hypoxia ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Wild Type ◽  
Nf Kappa B ◽  
Macrophage Foam Cell ◽  
Obstructive Sleep ◽  
Intracellular Cholesterol

Background: Obstructive sleep apnea syndrome (OSAS) is a common sleeping disorder characterized by intermittent hypoxia (IH). Clinical studies have previously shown an independent association between obstructive sleep apnea and atherosclerosis. Furthermore, it has been previously shown that such a predisposition to atherosclerosis in OSAS patient can be caused by various inflammatory mediators, particularly the NF-kappa B (NF-kB) pathway. Foam cells or lipid-laden macrophages in the atherosclerotic lesion have been well documented as a hallmark of atherosclerosis; however, the contribution of IH, such as in OSAS, to foam cell formation is not yet fully understood. Previous observations have led us to hypothesized that IH induces macrophage foam cell formation due to the activation of NF-kappa B pathway. Methods: Myeloid restricted IKK-beta deleted mice were generated by a Cre/lox recombination system to inactivate the NF-kB pathway in macrophages. Thioglycollate-elicited peritoneal macrophages were incubated with 200 μg/ml of low-density lipoprotein and simultaneously exposed to either IH (Normoxia: 8min, 0.5% O2: 10min) or normoxia for 24 hours. After exposure, the extent of foam cell formation was assessed by quantification of intracellular cholesterol. Finally, we compared the differences in gene expression using RNA-seq between wild type and IKK-beta deleted macrophages exposed to either IH or normoxia for 24 hours. Results: IH significantly increased total cholesterol in wild type macrophages (63.4±3.3 μg/mg of cellular protein, n=9) in comparison to normoxia (51.2±1.6). Interestingly, such increase in intracellular cholesterol in response to IH-exposure was abolished by IKK-beta deletion (IH 52.4±1.1; normoxia 50.0±1.6 n=8), suggesting that NF-kB pathway regulated gene expression is critical for IH-induced foam cell formation. Indeed, we have found that NF-kB knockout abolished IH-induced expressional alterations in 364 genes, which are potential candidates for regulating intracellular cholesterol. Conclusion: NF-kB activation plays a critical role in IH-induced macrophage foam cell formation.

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