Copy Number of an Integron-Encoded Antibiotic Resistance Locus Regulates a Virulence and Opacity Switch in Acinetobacter baumannii AB5075
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ABSTRACT:
PROVIDER: PRJNA657043 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR12450059.fastq.gz | Fastqsanger.gz | |||
| SRR12450060.fastq.gz | Fastqsanger.gz | |||
| SRR12450061.fastq.gz | Fastqsanger.gz | |||
| SRR12450062.fastq.gz | Fastqsanger.gz | |||
| SRR12450063.fastq.gz | Fastqsanger.gz |
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Project description:We describe a novel genetic mechanism in which tandem amplification of a plasmid-borne integron regulates virulence, opacity variation, and global gene expression by altering levels of a putative small RNA (sRNA) in Acinetobacter baumannii AB5075. Copy number of this amplified locus correlated with the rate of switching between virulent opaque (VIR-O) and avirulent translucent (AV-T) cells. We found that prototypical VIR-O colonies, which exhibit high levels of switching and visible sectoring with AV-T cells by 24 h of growth, encode two copies of this locus. However, a subset of opaque colonies that did not form AV-T sectors within 24 h were found to encode only one copy. The colonies with decreased sectoring to AV-T were designated low-switching opaque (LSO) variants, and were found to exhibit a three-log decrease in switching relative to the VIR-O. Overexpression studies revealed that the element regulating switching was localized to the 5’ end of the aadB gene within the amplified locus. Northern blotting indicated that a sRNA of approximately 300 nt is encoded in this region, and is likely responsible for regulating switching to AV-T. Copy number of the ~300 nt sRNA was also found to affect virulence, as the LSO variant exhibited decreased virulence during murine lung infections. Global transcriptional profiling revealed that over 100 genes were differentially expressed between VIR-O and LSO variants, suggesting that the ~300 nt sRNA may act as a global regulator. Several virulence genes exhibited decreased expression in LSO cells, potentially explaining their decreased virulence.
2020-08-13 | GSE156206 | GEO
Project description:We describe a novel genetic mechanism in which tandem amplification of a plasmid-borne integron regulates virulence, opacity variation, and global gene expression by altering levels of a putative small RNA (sRNA) in Acinetobacter baumannii AB5075. Copy number of this amplified locus correlated with the rate of switching between virulent opaque (VIR-O) and avirulent translucent (AV-T) cells. We found that prototypical VIR-O colonies, which exhibit high levels of switching and visible sectoring with AV-T cells by 24 h of growth, harbor two copies of this locus. However, a subset of opaque colonies that did not form AV-T sectors within 24 h were found to harbor only one copy. The colonies with decreased sectoring to AV-T were designated low-switching opaque (LSO) variants and were found to exhibit a 3-log decrease in switching relative to that of the VIR-O. Overexpression studies revealed that the element regulating switching was localized to the 5' end of the aadB gene within the amplified locus. Northern blotting indicated that an sRNA of approximately 300?nucleotides (nt) is encoded in this region and is likely responsible for regulating switching to AV-T. Copy number of the ?300-nt sRNA was also found to affect virulence, as the LSO variant exhibited decreased virulence during murine lung infections. Global transcriptional profiling revealed that >100 genes were differentially expressed between VIR-O and LSO variants, suggesting that the ?300-nt sRNA may act as a global regulator. Several virulence genes exhibited decreased expression in LSO cells, potentially explaining their decreased virulence.IMPORTANCE Acinetobacter baumannii remains a leading cause of hospital-acquired infections. Widespread multidrug resistance in this species has prompted the WHO to name carbapenem-resistant A. baumannii as its top priority for research and development of new antibiotics. Many strains of A. baumannii undergo a high-frequency virulence switch, which is an attractive target for new therapeutics targeting this pathogen. This study reports a novel mechanism controlling the frequency of switching in strain AB5075. The rate of switching from the virulent opaque (VIR-O) to the avirulent translucent (AV-T) variant is positively influenced by the copy number of an antibiotic resistance locus encoded on a plasmid-borne composite integron. Our data suggest that this locus encodes a small RNA that regulates opacity switching. Low-switching opaque variants, which harbor a single copy of this locus, also exhibit decreased virulence. This study increases our understanding of this critical phenotypic switch, while also identifying potential targets for virulence-based A. baumannii treatments.
| S-EPMC7542366 | biostudies-literature
Project description:RNA-seq was used to compare the transcriptomes of wild type A. baumannii AB5075 and a spontaneously arising grey colony variant that carries a copy of the insertion sequence ISAba13 within the gtr52 gene.
2024-07-15 | E-MTAB-13791 | biostudies-arrayexpress
Project description:Acinetobacter baumannii AB5075 Genome sequencing and assembly
| PRJNA168474 | ENA
Project description:We perform RNA-seq comparing a treatment with 0.375 mM Kaempferol to a mock treatment (DMSO) in A. baumannii AB5075 in order to describe the alterations in global transcription produced by this phytochemical. A. baumannii AB5075 cultures were grown in LB medium in the presence of 0.375 mM Kaempferol or a DMSO control (3 biological replicates per condition) until reaching mid-exponential phase. At this point, cells were harvested, treated with RNAlater for preservation of total RNA and stored at -80 C. After that, total RNA was extracted from each sample. As a result, 99 genes appeared upregulated in the presence of Kaempferol whereas 18 were downregulated. In highlights, the gene functional groups showing the strongest transcriptional alterations were those related to iron acquisition, siderophore biosynthesis and iron transport genes.
2023-09-20 | GSE212989 | GEO
Project description:Acinetobacter baumannii AB5075-UW Genome sequencing
| PRJNA266336 | ENA
Project description:The experiment contains native Tn-seq data for Acinetobacter baumannii strain AB5075 with different genetic alterations. The strain was grown at 37 degrees in LB medium and genomic DNA was isolated. We then used PCR to select for DNA regions containing a junction between ISAba13 and chromosomal DNA. Libraries were then prepared using these DNA fragments.
2024-07-15 | E-MTAB-13792 | biostudies-arrayexpress
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
Project description:Acinetobacter baumannii strain:AB5075-UW Genome sequencing
| PRJNA243297 | ENA
Project description:The experiment contains ChIP-seq data for Acinetobacter baumannii strain AB5075 encoding 3xFLAG tagged H-NS. Experiments were done with or without ectopic expression of the truncated H-NS-39 protein (corresponding to the H-NS multimerization surface). The strain was grown at 37 degrees in LB medium and crosslinked with 1 % (v/v) formaldehyde. After sonication, to break open cells and fragment DNA, immunoprecipitations were done using anti-FLAG antibodies against. Libraries were prepared using DNA remaining after immunoprecipitation.
2024-07-15 | E-MTAB-13790 | biostudies-arrayexpress