Vancomycin binding to low-affinity ligands: delineating a minimum set of interactions necessary for high-affinity...

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Bacterial resistance to vancomycin is a growing concern.
• This resistance is often linked to changes in bacterial cell wall biosynthesis, specifically the use of depsipeptide intermediates instead of polypeptide intermediates.
• The loss of a key hydrogen bond interaction between vancomycin and its target is hypothesized to reduce drug binding affinity.

Purpose of the Study:

• To investigate the importance of the hydrogen bond in vancomycin binding.
• To determine the structural basis for vancomycin's reduced affinity to depsipeptide targets.
• To identify factors contributing to vancomycin resistance.

Main Methods:

• Determined crystal structures of vancomycin complexes with three specific ligands (N-acetylglycine, D-lactic acid, and 2-acetoxy-D-propanoic acid) at 1.0 A resolution.
• Analyzed these structures in conjunction with previously reported data.
• Defined minimal drug-ligand interactions for high-affinity binding.

Main Results:

• Observed that higher-affinity ligands induce a structural change in vancomycin not seen with lower-affinity ligands.
• Identified a minimal set of interactions required for high-affinity ligand binding.
• Found that factors beyond the loss of a single hydrogen bond contribute to vancomycin's weaker affinity for depsipeptide ligands.

Conclusions:

• The loss of the intermolecular hydrogen bond is not the sole reason for vancomycin resistance.
• Additional factors influence vancomycin binding affinity to depsipeptide targets.
• Understanding these factors is crucial for designing novel vancomycin analogues to combat bacterial resistance.