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| Status |
Public on Aug 13, 2020 |
| Title |
Copy Number of an Integron-Encoded Antibiotic Resistance Locus Regulates a Virulence and Opacity Switch in Acinetobacter baumannii AB5075 |
| Organism |
Acinetobacter baumannii |
| Experiment type |
Expression profiling by high throughput sequencing
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| Summary |
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.
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| Overall design |
A. baumannii cultures representative of the LSO and VIR-O (control) subpopulations were grown to an OD of 0.5 in LB medium. Gene expression was measured via RNA-sequencing for three biological replicates per sample.
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| Contributor(s) |
Anderson SE, Chin CY, Weiss DS, Rather PN, Tharp GK |
| Citation(s) |
33024041 |
| |
| Submission date |
Aug 13, 2020 |
| Last update date |
Oct 27, 2020 |
| Contact name |
Gregory K Tharp |
| E-mail(s) |
[email protected]
|
| Phone |
404-727-7797
|
| Organization name |
Yerkes National Primate Research Center
|
| Department |
Developmental and Cognitive Neuroscience
|
| Lab |
Genomics Core
|
| Street address |
954 Gatewood Dr
|
| City |
Atlanta |
| State/province |
GA |
| ZIP/Postal code |
30329-4208 |
| Country |
USA |
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| Platforms (1) |
| GPL26038 |
Illumina HiSeq 3000 (Acinetobacter baumannii) |
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| Samples (6)
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| Relations |
| BioProject |
PRJNA657043 |
| SRA |
SRP277421 |
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