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| Status |
Public on Feb 01, 2014 |
| Title |
Inducible expression of macrolide efflux in Streptococcus pneumoniae is controlled by transcriptional attenuation of the mef(E)/mel operon |
| Organism |
Streptococcus pneumoniae |
| Experiment type |
Expression profiling by high throughput sequencing
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| Summary |
Macrolide resistance, increasingly identified in Streptococcus pneumoniae and a wide range of other Gram-positive bacteria, is often due to efflux pumps encoded by the mef/mel(msr) operon found on discrete mobile genetic elements. The regulation of mef/mel(msr) in these elements is not well understood. We defined the promoter controlling the mef(E)/mel operon in S. pneumoniae, identified cis-acting 5′ regulatory elements and determined the mechanism of macrolide-inducible expression of the efflux pump.
The mef(E)/mel transcriptional start site was a guanine 327 bp upstream of the mef(E) start codon. Consensus pneumococcal promoter -10 (5′-TATACT-3′) and -35 (5′-TTGAAC-3′) boxes separated by a 17 bp spacer were identified 7 bp upstream of the start site. Analysis of the predicted secondary structure of the 327 bp 5’ region identified four pairs of inverted repeats R1-R8 predicted to fold into stem-loops, a small leader peptide (MTASMRLR) required for macrolide induction and a Rho-independent transcription terminator involving the R5/R6 stem loop. Mutational analyses of the regulatory region identified transcriptional attenuation as the model for the inducible expression of macrolide efflux, which was confirmed by RNA-Seq expression data. The 327 bp region 5’ of mef(E) was highly conserved in other mef/mel(msr)-containing genetic elements complexes including Tn1207.1 and the 5612IQ complex in pneumococci and Tn1207.3 in Group A streptococci. Induction of the mef(E)/mel operon and macrolide efflux occurs by anti-attenuation in the presence of inducing macrolides and appears to be a mechanism
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| Overall design |
RNA-seq was performed on wild type and mutant cultures of four strains of Streptococcus pneumoniae untreated, or treated with spiramycin, LL-37 or erythromycin
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| Contributor(s) |
Tettelin H, Bai X, Kumar N, Drábek EF, Daugherty S, Colon T, Ott S, Sengamalay N, Sadzewicz L, Tallon LJ, Stephens DS, Chancey ST |
| Citation(s) |
25695510 |
| |
| Submission date |
Jan 16, 2014 |
| Last update date |
May 15, 2019 |
| Contact name |
Hervé Tettelin |
| E-mail(s) |
tettelin@som.umaryland.edu
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| Phone |
(410) 706-6764
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| Organization name |
University of Maryland
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| Department |
Institute for Genome Sciences
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| Street address |
801 W Baltimore St
|
| City |
Baltimore |
| State/province |
MD |
| ZIP/Postal code |
21201 |
| Country |
USA |
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| Platforms (1) |
| GPL18183 |
Illumina HiSeq 2000 (Streptococcus pneumoniae) |
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| Samples (46)
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| Relations |
| BioProject |
PRJNA235338 |
| SRA |
SRP035481 |
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