title: Transcriptional attenuation controls macrolide inducible efflux and resistance in Streptococcus pneumoniae and in other Gram-positive bacteria containing mef/mel(msr(D)) elements.
abstract: Macrolide resistance, emerging in Streptococcus pneumoniae and other Gram-positive bacteria, is increasingly due to efflux pumps encoded by mef/mel(msr) operons found on discrete mobile genetic elements. The regulation of mef/mel(msr) in these elements is not well understood. We identified the mef(E)/mel transcriptional start, localized the mef(E)/mel promoter, and demonstrated attenuation of transcription as a mechanism of regulation of macrolide-inducible mef-mediated macrolide resistance in S. pneumoniae. The mef(E)/mel transcriptional start site was a guanine 327 bp upstream of mef(E). Consensus pneumococcal promoter -10 (5'-TATACT-3') and -35 (5'-TTGAAC-3') boxes separated by 17 bp were identified 7 bp upstream of the start site. Analysis of the predicted secondary structure of the 327 5' region identified four pairs of inverted repeats R1-R8 predicted to fold into stem-loops, a small leader peptide [MTASMRLR, (Mef(E)L)] required for macrolide induction and a Rho-independent transcription terminator. RNA-seq analyses provided confirmation of transcriptional attenuation. In addition, expression of mef(E)L was also influenced by mef(E)L-dependent mRNA stability. The regulatory region 5' of mef(E) was highly conserved in other mef/mel(msr)-containing elements including Tn1207.1 and the 5612IQ complex in pneumococci and Tn1207.3 in Group A streptococci, indicating a regulatory mechanism common to a wide variety of Gram-positive bacteria containing mef/mel(msr) elements.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America; Laboratories of Microbial Pathogenesis, Department of Veterans Affairs Medical Center, Atlanta, Georgia, United States of America.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Chancey
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America; Laboratories of Microbial Pathogenesis, Department of Veterans Affairs Medical Center, Atlanta, Georgia, United States of America.
authors.forename: Xianhe
authors.initials: X
authors.lastname: Bai
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Elliott F
authors.initials: EF
authors.lastname: Drabek
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Daugherty
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: Colon
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Sandra
authors.initials: S
authors.lastname: Ott
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Naomi
authors.initials: N
authors.lastname: Sengamalay
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Lisa
authors.initials: L
authors.lastname: Sadzewicz
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Tallon
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Fraser
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America; Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Hervé
authors.initials: H
authors.lastname: Tettelin
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America; Laboratories of Microbial Pathogenesis, Department of Veterans Affairs Medical Center, Atlanta, Georgia, United States of America.
authors.forename: David S
authors.initials: DS
authors.lastname: Stephens
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides