Mutagenesis of 16S rRNA C1409-G1491 base-pair differentiates between 6'OH and 6'NH3+ aminoglycosides.
Using a single rRNA allelic Gram-positive model system, we systematically mutagenized 16S rRNA positions 1409 and 1491 to probe the functional relevance of structural interactions between aminoglycoside antibiotics and the A-site rRNA that were suggested by X-ray crystallography. At the structural level, the interaction of the 2-deoxystreptamine aminoglycosides with the rRNA base-pair C1409-G1491 has been suggested to involve the following features: (i) ring I of the disubstituted 2-deoxystreptamines stacks upon G1491 and H-bonds to the Watson-Crick edge of A1408; (ii) ring III of the 4,5-disubstituted aminoglycosides shows hydrogen bonding to G1491. However, we found that mutants with altered 16S rRNA bases 1409 and 1491 discriminated poorly between 4,5-disubstituted and 4,6-disubstituted 2-deoxystreptamines, but differentially affected aminoglycosides with a hydroxyl group versus an ammonium group at position 6' of ring I, e.g. G1491U conferred high-level drug resistance to paromomycin and geneticin, but not to neomycin, tobramycin or gentamicin.
Pfister
P
P
Institut für Medizinische Mikrobiologie, Universität Zürich, Gloriastr. 30/32, CH-8028 Zürich, Switzerland.
Hobbie
S
S
Brüll
C
C
Corti
N
N
Vasella
A
A
Westhof
E
E
Böttger
E C
EC
D000617:Aminoglycosides / Q000737:chemistry*; D000900:Anti-Bacterial Agents; D020029:Base Pairing; D001665:Binding Sites; D004351:Drug Resistance / Q000235:genetics; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics; D006595:Hexosamines; D006860:Hydrogen Bonding; D016297:Mutagenesis, Site-Directed; D020102:Mycobacterium smegmatis / Q000166:cytology / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000737:chemistry* / Q000235:genetics*; D013379:Substrate Specificity / Q000235:genetics
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D006595:Hexosamines; D012336:RNA, Ribosomal, 16S; C002980:streptamine