Biochemical Activity of Vaborbactam

Area of Science:

• Biochemistry
• Microbiology
• Pharmacology

Background:

• Gram-negative bacteria commonly resist β-lactam antibiotics via β-lactamase enzymes.
• Inhibiting these enzymes is crucial for restoring antibiotic efficacy.
• Vaborbactam is an approved cyclic boronic acid β-lactamase inhibitor (BLI).

Purpose of the Study:

• To elucidate the mechanism of action of vaborbactam.
• To kinetically characterize vaborbactam's interaction with various β-lactamases.
• To assess the stability of vaborbactam-β-lactamase complexes.

Main Methods:

• Detailed kinetic characterization of vaborbactam with recombinant His-tagged β-lactamases.
• Determination of inhibition constants (K_i) and inactivation constants (k₂/K).
• Enzyme activity recovery experiments to assess complex stability (k_off).

Main Results:

• Vaborbactam showed potent inhibition of class A and C β-lactamases (K_i: 0.022–0.18 μM), with poor activity against class D and no activity against class B.
• It inhibited KPC carbapenemases with 1:1 stoichiometry and acted as a progressive inactivator.
• The vaborbactam-KPC complex exhibited high stability with a slow dissociation rate (k_off = 0.000040 s^-1, residence time ~7 h).

Conclusions:

• Vaborbactam's potent inhibition and stable complex formation with KPC carbapenemases are key to its efficacy.
• Understanding these biochemical characteristics can guide the development of next-generation boronic acid BLIs.
• Further optimization may lead to inhibitors with enhanced affinity and broader-spectrum activity against resistant bacteria.