Structure of VanS from vancomycin-resistant enterococci: A sensor kinase with weak ATP binding

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• The VanRS two-component system controls vancomycin resistance in enterococci.
• VanS, a sensor histidine kinase, initiates resistance gene expression upon vancomycin detection.
• Structural data for VanS proteins were previously unavailable, limiting mechanistic understanding.

Purpose of the Study:

• To elucidate the structural basis of VanS protein function.
• To investigate the interaction of VanS with ATP.
• To understand the regulation of vancomycin resistance at a molecular level.

Main Methods:

• X-ray crystallography was used to determine the structures of the catalytic and ATP-binding (CA) domains of VanS proteins from vancomycin-resistant enterococci types A and C.
• Binding affinities for ATP were measured using biochemical assays.

Main Results:

• The crystal structures revealed that both VanS CA domains adopt the canonical Bergerat fold.
• Attempts to crystallize nucleotide-bound forms were unsuccessful.
• Both VanS CA domains exhibited low affinities for ATP (K_D in the millimolar range), comparable to intracellular ATP levels.

Conclusions:

• The weak ATP binding affinity of VanS CA domains may represent a regulatory mechanism for controlling the vancomycin resistance phenotype.
• These structural and biochemical findings provide a foundation for understanding VanRS system regulation.
• Further research can explore how this weak binding impacts resistance gene expression.