Limits...
Investigating the entire course of telithromycin binding to Escherichia coli ribosomes.

Kostopoulou ON, Petropoulos AD, Dinos GP, Choli-Papadopoulou T, Kalpaxis DL - Nucleic Acids Res. (2012)

Bottom Line: In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding.Polyamines disfavor both sequential steps of binding.Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece.

ABSTRACT
Applying kinetics and footprinting analysis, we show that telithromycin, a ketolide antibiotic, binds to Escherichia coli ribosomes in a two-step process. During the first, rapidly equilibrated step, telithromycin binds to a low-affinity site (K(T) = 500 nM), in which the lactone ring is positioned at the upper portion of the peptide exit tunnel, while the alkyl-aryl side chain of the drug inserts a groove formed by nucleotides A789 and U790 of 23S rRNA. During the second step, telithromycin shifts slowly to a high-affinity site (K(T)* = 8.33 nM), in which the lactone ring remains essentially at the same position, while the side chain interacts with the base pair U2609:A752 and the extended loop of protein L22. Consistently, mutations perturbing either the base pair U2609:A752 or the L22-loop hinder shifting of telithromycin to the final position, without affecting the initial step of binding. In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding. Polyamines disfavor both sequential steps of binding. Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.

Show MeSH

Related in: MedlinePlus

Competition between telithromycin (T) and tylosin (I) for binding to ribosomal complex C.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3367204&req=5

gks174-SCH1: Competition between telithromycin (T) and tylosin (I) for binding to ribosomal complex C.


Investigating the entire course of telithromycin binding to Escherichia coli ribosomes.

Kostopoulou ON, Petropoulos AD, Dinos GP, Choli-Papadopoulou T, Kalpaxis DL - Nucleic Acids Res. (2012)

Competition between telithromycin (T) and tylosin (I) for binding to ribosomal complex C.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3367204&req=5

gks174-SCH1: Competition between telithromycin (T) and tylosin (I) for binding to ribosomal complex C.
Bottom Line: In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding.Polyamines disfavor both sequential steps of binding.Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece.

ABSTRACT
Applying kinetics and footprinting analysis, we show that telithromycin, a ketolide antibiotic, binds to Escherichia coli ribosomes in a two-step process. During the first, rapidly equilibrated step, telithromycin binds to a low-affinity site (K(T) = 500 nM), in which the lactone ring is positioned at the upper portion of the peptide exit tunnel, while the alkyl-aryl side chain of the drug inserts a groove formed by nucleotides A789 and U790 of 23S rRNA. During the second step, telithromycin shifts slowly to a high-affinity site (K(T)* = 8.33 nM), in which the lactone ring remains essentially at the same position, while the side chain interacts with the base pair U2609:A752 and the extended loop of protein L22. Consistently, mutations perturbing either the base pair U2609:A752 or the L22-loop hinder shifting of telithromycin to the final position, without affecting the initial step of binding. In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding. Polyamines disfavor both sequential steps of binding. Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.

Show MeSH
Related in: MedlinePlus