Structural features and kinetic characterization of alanine racemase from Staphylococcus aureus (Mu50)

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Staphylococcus aureus is a major cause of hospital-acquired infections, with antibiotic-resistant strains posing significant treatment challenges.
• Alanine racemase (Alr) is crucial for bacterial cell-wall synthesis and absent in humans, making it a promising antibiotic target.
• The emergence of antibiotic-resistant bacteria necessitates the development of novel therapeutic strategies.

Purpose of the Study:

• To determine the crystal structure of Staphylococcus aureus alanine racemase (Alr(Sas)) from an antibiotic-resistant strain.
• To provide structural insights for the rational design of new inhibitors targeting Alr(Sas).
• To characterize the enzyme's kinetic properties and identify potential drug development avenues.

Main Methods:

• X-ray crystallography was used to solve the crystal structure of Alr(Sas) at 2.15 Å resolution.
• Bioinformatics tools were employed for structural comparisons with other alanine racemases.
• Enzyme kinetics were analyzed to determine kinetic constants.

Main Results:

• The crystal structure of Alr(Sas) revealed a conserved overall fold, similar to other Gram-positive bacterial alanine racemases.
• Key structural features, including the active-site binding pocket and dimer interface, were identified as potential inhibitor targets.
• Kinetic constants for Alr(Sas) were determined and reported.

Conclusions:

• The solved Alr(Sas) structure serves as a valuable template for structure-based drug design against S. aureus.
• Targeting Alr(Sas) offers a promising strategy to combat antibiotic-resistant Staphylococcus aureus infections.
• Further research into Alr(Sas) inhibitors could lead to the development of urgently needed new antibiotics.