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PpGpp signal plays critical role in pathogenesis of Acinetobacter baumannii 17978

ABSTRACT: Acinetobacter baumannii is a major cause of nosocomial infections which can survive in different hospital environments and its multidrug-resistant capacity is major concern now-a-days. ppGpp dependent stringent response mediates reprogramming of gene expression with diverse function in many bacteria. A baumannii A1S_0579 gene is responsible for ppGpp production. Transcriptome analysis of early stationary phase cultures represents several differentially expressed genes in ppGpp deficient strain (∆A1S_0579). We found that the expression of csu operon, which is important in pili biosynthesis for early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings showed that ppGpp signaling plays critical role in biofilm formation, surface motility, adherence and virulence of A baumannii. This study is the first demonstration of the association between ppGpp and pathogenicity of A. baumannii.

ORGANISM(S): Acinetobacter baumannii

PROVIDER: GSE173627 | GEO | 2021/05/01

REPOSITORIES: GEO

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Transcriptomic profiling by RNA-seq of A. baumannii 17978 wild-type, and ∆A1S_1874 mutants.

Project description:Acinetobacter baumannii A1S_1874 gene encodes as a LysR-type transcriptional regulator. LysR family regulators known to regulate biofilm formation, antibiotic resistance, and the expression of diverse genes in other Gram-negative bacteria. However, A1S-1874 has never been characterized in Acinetobacter baumannii, and the studies about the regulon of A1S-1874 are not discovered. In this study we revealed that A1S_1874 differentially regulates at least 302 genes including the csu pilus operon, N-acylhomoserine lactone synthese gene, A1S_0112-A1S_0118 operon, type 1v secretion system related genes that are involved in biofilm formation, surface motility, adherence, quorum sensing and virulence. Overall, our data suggests that A1S-1874 is a key regulator of Acinetobacter baumannii biofilm formation and gene expression.

2021-05-25 | GSE173626 | GEO

Fine-tuning regulation of (p)ppGpp-driven outer membrane vesicle formation in Acinetobacter baumannii

Project description:While the roles of (p)ppGpp on cytosolic proteins are well established, its effects on membrane remodeling remain elusive. The translocation of signal recognition particle (SRP)-dependent proteins can be regulated by binding (p)ppGpp to two key GTPase components: FtsY, which interacts with SecYEG, and Ffh, a homolog of SRP54. A (p)ppGpp-specific Broccoli RNA aptamer and the chemometer PyDPA were used to measure the (p)ppGpp levels in the ΔrelA and ΔrelA/ΔspoT strains of Acinetobacter baumannii, confirming a stepwise reduction in (p)ppGpp levels: wild type > ΔrelA > ΔrelA/ΔspoT. The overproduction of outer membrane vesicles (OMVs) in the ΔrelA strain with intermediate (p)ppGpp levels contrasts with reduced production in the ΔrelA/ΔspoT strain, highlighting an unexpected non-linear relationship between OMV production and (p)ppGpp levels. Scanning- and transmission- electron microscope (SEM and TEM) analyses revealed intriguing (p)ppGpp-dependent effects on cell envelope integrity, as the relA mutant showed outer membrane disruption leading to OMV formation, while the relA/spoT mutant maintained an intact outer membrane, suggesting a correlation between (p)ppGpp levels and membrane stability. Western blotting and proteomics analyses revealed significant OmpA accumulation in the inner membrane of the ΔrelA/ΔspoT strain and SRP-dependent inner membrane proteins such as NuoB, NuoL, and TolA in the ΔrelA strain, indicating that (p)ppGpp levels are crucial for regulating membrane protein incorporation in A. baumannii. The regulation of (p)ppGpp levels using the CRISPRi system revealed that outer membrane disruption and OMV formation were most significant at intermediate (p)ppGpp concentrations, highlighting the importance of fine-tuning (p)ppGpp for the regulation of bacterial phenotypes.

2025-03-15 | PXD057710 | Pride

The primary transcriptome of Acinetobacter baumannii ATCC 17978

Project description:Transcriptomics by RNA-seq provides unparalleled insight into bacterial gene expression networks, enabling a deeper understanding of the regulation of pathogenicity, mechanisms of antimicrobial resistance, metabolism, and other cellular processes. Here we present the transcriptome architecture of Acinetobacter baumannii ATCC 17978, a species emerging as a leading cause of antimicrobial resistant nosocomial infections. Differential RNA-seq (dRNA-seq) examination of model strain ATCC 17978 in 16 laboratory conditions identified 3731 transcriptional start sites (TSS), and 110 small RNAs, including the first identification of 22 sRNA encoded at the 3′ end of mRNA.

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RelA/(p)ppGpp regulates the glucose-starvation induced stringent response in the zoonostic Streptococcus suis

2015-08-08 | GSE70092 | GEO

RelA/(p)ppGpp regulates the glucose-starvation induced stringent response in the zoonostic Streptococcus suis

Project description:Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays relA mutant strain and its parents strain SC-19 were cultured in both glucose-abundant CDM (CDM containing 1% glucose) and glucose-deficient CDM (CDM containing 2% glucose) respectively. The bacteriain in exponential phase were collected for microarray analysis. Three independent experiments were performed.

2015-08-08 | E-GEOD-70092 | biostudies-arrayexpress

Effect of ppGpp on Salmonella Typhimurium gene expression

Project description:The expression profile of an S. Typhimurium mutant strain unable to synthesise ppGpp (relAspoT deletions) was compared to the wild-type strain. The effect of ppGpp on virulence gene expression was studied under 4 different growth conditions that induce virulence gene expression. Keywords: genetic modification

2006-05-30 | GSE4631 | GEO

Transcription regulation by CavA cyclase in Acinetobacter baumannii AB5075

Project description:We perform RNA-seq for comparison of deleted cavA wiht empty vector and complemented strains in A. baumannii AB5075 in order to assess the transcription regulation uder the control of this cyclase. A. baumannii AB5075 ΔcavA EV and ΔcavA+cavA cultures were grown in LB medium with 1mM IPTG (3 biological replicates per strain) until reaching mid-exponential phase. At this point, cells were harvested, treated with RNAlate for preservation of total RNA and stored at -80 C. After that, total RNA was extracted from each sample. The results showed 234 differentially expressed genes of which 143 were upregulated and 91 were downregulated in the ΔcavA+cavA complemented strain compared to the deleted cavA mutant harbouring empty vector (ΔcavA EV). The gene functional groups showing the strongest transcriptional alterations were those related to twitching motility (upregulation of genes involves in biogenesis and control of Type IV pili and com genes) as well as biofilm formation, exopolysaccharides production and fimbriae biogenesis (downregulation of csu operon, pga operon and ABUW_2052-2055). Also, genes related to inter- and intracellular signalling were differentially expressed. Cyclic AMP response regulator vfr and genes involved in c-di-GMP synthesis (ABUW_2135) and degradation (ABUW_1138) were upregulated while another gene linked to c-di-GMP degradation (ABUW_2631) and autoinducer synthase encoding gene abaI (part of the quorum sensing signalling system) were downregulated.

2024-08-30 | GSE250425 | GEO

ppGpp signal plays critical role in pathogenesis of Acinetobacter baumannii 17978

Project description:ppGpp signal plays critical role in pathogenesis of Acinetobacter baumannii 17978

| PRJNA726423 | ENA

Expression Data from Acinetobacter baumannii strain ATCC 17978 and isogenic lpsB mutant cells

Project description:lpsB encodes a glycosyltransferase involved in lipopolysaccharide (LPS) synthesis. LPS is a major component of the Gram-negative bacterial outer membranes. We used custom-made Affymetrix A. baumannii strain ATCC 17978 derived GeneChips to compare the gene expression properties of wild type and isogenic lpsB mutant cells. Two mutants were evaluated; A. baumannii strain 5A7 is a ATCC 17978 derivative harboring a transposon (Tn5) within lpsB (A1S_0430 locus); A. baumannii strain containing a deletion of lpsB (A1S_0430).

2012-12-01 | GSE40771 | GEO

(p)ppGpp promotes Enterococcus faecalis virulence in a murine model of catheter-associated urinary tract infection

Project description:In Firmicutes, the nutrient-sensing regulators (p)ppGpp, the effector molecule of the stringent response, and CodY work in tandem to maintain bacterial fitness during infection. Here, we tested (p)ppGpp and codY mutant strains of Enterococcus faecalis in a catheter-associated urinary tract infections (CAUTI) mouse model and used global transcriptional analysis to investigate the (p)ppGpp and CodY relationship. Absence of (p)ppGpp or single inactivation of codY led to lower bacterial loads in catheterized bladders, and diminished biofilm formation on fibrinogen-coated surfaces under in vitro and in vivo conditions. Single inactivation of the bifunctional (p)ppGpp synthetase/hydrolase rel did not affect virulence supporting previous evidence that association of (p)ppGpp with enterococcal virulence is not dependent on activation of the stringent response. Inactivation of codY in the (p)ppGpp0 strain restored E. faecalis virulence in the CAUTI model as well as the ability to form biofilms in vitro. Transcriptome analysis revealed that inactivation of codY restores, for the most part, the dysregulated metabolism of (p)ppGpp0 cells. While a clear linkage between (p)ppGpp and CodY with expression of virulence factors could not be established, targeted transcriptional analysis indicate that a possible association between (p)ppGpp and c-di-AMP signaling pathways in response to the conditions found in the bladder may plays a role in enterococcal CAUTI. Collectively, this study identifies the (p)ppGpp-CodY network as an important contributor to enterococcal virulence in catheterized mouse bladder and supports that basal (p)ppGpp pools promote virulence through maintenance of a balanced metabolism during adverse conditions.

2019-05-25 | GSE131749 | GEO

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