Beta-lactamase class D enzyme (None)

Class D β-lactamases, also known as oxacillinases (OXA-type β-lactamases), are a diverse group of serine-dependent enzymes produced by bacteria. They confer resistance to β-lactam antibiotics by hydrolyzing the characteristic four-membered β-lactam ring found in these drugs, thereby inactivating their antibacterial properties. These enzymes are particularly notable for their genetic and biochemical diversity and play a significant role in antibiotic resistance among Gram-negative pathogens such as Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and Proteus mirabilis. A unique feature is a post-translationally carbamylated lysine residue (Lys70 or Lys74), which acts as a general base during catalysis—this modification is critical for enzymatic activity and distinguishes class D from other serine-based classes. The emergence of plasmid-borne OXA-type genes has led to widespread resistance against many frontline antibiotics—including last-resort agents like carbapenems—in major nosocomial pathogens. Their diversity complicates detection and treatment strategies due to variable substrate profiles across different enzyme variants.

Other names

OxacillinaseOXA-type beta-lactamase

Serine-dependent hydrolysis via nucleophilic attack on beta lactam ring