title: 23S rRNA base pair 2057-2611 determines ketolide susceptibility and fitness cost of the macrolide resistance mutation 2058A-->G.
abstract: The 23S rRNA A2058G alteration mediates macrolide, lincosamide, and streptogramin B resistance in the bacterial domain and determines the selectivity of macrolide antibiotics for eubacterial ribosomes, as opposed to eukaryotic ribosomes. However, this mutation is associated with a disparate resistance phenotype: It confers high-level resistance to ketolides in mycobacteria but only marginally affects ketolide susceptibility in streptococci. We used site-directed mutagenesis of nucleotides within domain V of 23S rRNA to study the molecular basis for this disparity. We show that mutational alteration of the polymorphic 2057-2611 base pair from A-U to G-C in isogenic mutants of Mycobacterium smegmatis significantly affects susceptibility to ketolides but does not influence susceptibility to other macrolide antibiotics. In addition, we provide evidence that the 2057-2611 polymorphism determines the fitness cost of the 23S rRNA A2058G resistance mutation. Supported by structural analysis, our results indicate that polymorphic nucleotides mediate the disparate phenotype of genotypically identical resistance mutations and provide an explanation for the large species differences in the epidemiology of defined drug resistance mutations.
authors.affiliation: Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastrasse 30/32, CH-8006 Zürich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Pfister
authors.forename: Natascia
authors.initials: N
authors.lastname: Corti
authors.forename: Sven
authors.initials: S
authors.lastname: Hobbie
authors.forename: Christian
authors.initials: C
authors.lastname: Bruell
authors.forename: Raz
authors.initials: R
authors.lastname: Zarivach
authors.forename: Ada
authors.initials: A
authors.lastname: Yonath
authors.forename: Erik C
authors.initials: EC
authors.lastname: Böttger
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017291:Clarithromycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D048628:Ketolides / Q000737:chemistry / Q000494:pharmacology; D018942:Macrolides / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020102:Mycobacterium smegmatis / Q000187:drug effects* / Q000235:genetics*; D009690:Nucleic Acid Conformation; D010641:Phenotype; D017354:Point Mutation; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics*; D013045:Species Specificity; D015645:Tylosin / Q000494:pharmacology
chemical_list: D048628:Ketolides; D018942:Macrolides; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin; C106791:telithromycin; D015645:Tylosin