Mutations in domain II of 23 S rRNA facilitate translation of a 23 S rRNA-encoded pentapeptide conferring erythromycin resistance.
Mutations in domain II of Escherichia coli 23 S rRNA that cause resistance to erythromycin do so in a manner fundamentally different from mutations at the drug binding site in domain V of the 23 S rRNA. The domain II mutations are located in a hairpin structure between nucleotides 1198 and 1247. This is close to a short open reading frame in the 23 S rRNA that encodes a pentapeptide (E-peptide) whose expression in vivo renders cells resistant to erythromycin. Therefore, a possible mechanism of resistance caused by domain II mutations may be related to an increased expression of the E-peptide. To test this hypothesis, a range of point mutations was generated in domain II of 23 S rRNA in the vicinity of the E-peptide open reading frame. We find a correlation between erythromycin resistance of the mutant clones and increased accessibility of the ribosome binding site of the E-peptide gene. Furthermore, the erythromycin resistance determinant in the mutants was shown to be confined to a small 23 S rRNA segment containing the coding region and the ribosome binding site of the E-peptide open reading frame. It thus appears that the domain II mutations mediate erythromycin resistance by increasing expression of the 23 S rRNA-encoded E-peptide.
Dam
M
M
Department of Molecular Biology, Odense University, Denmark.
Douthwaite
S
S
Tenson
T
T
Mankin
A S
AS
D001483:Base Sequence; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000235:genetics; D014176:Protein Biosynthesis; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics*
D010455:Peptides; D012338:RNA, Ribosomal, 23S; D004917:Erythromycin