Functional Characterization and Catalytic Mechanism of an Amidase Involved in Acetaminophen Degradation from Acinetobacter sp.
TL;DR
Findings provide mechanistic insights into bacterial APAP biodegradation and highlight the practical application potential of strain DL27 and AdA, a novel amidase (AdA) identified through high-resolution mass spectrometry.
Abstract
The accumulation of acetaminophen (APAP) in agricultural soils and water systems poses risks to ecosystems and public health. This study characterizes Acinetobacter sp. DL27, an APAP-degrading strain with broad temperature and pH adaptability, demonstrating its bioremediation potential in soil and wastewater. Through high-resolution mass spectrometry, we identified three novel metabolic intermediates, thereby refining the bacterial APAP degradation pathway. Multiomics analysis elucidated metabolic coordination and stress-tolerance mechanisms, leading to the identification of a novel amidase (AdA). Recombinant AdA exhibited activity over 10-60 °C and pH 4.0-10.0, with a Km of 8.96 ± 1.03 μM and a kcat/Km of 9.04 μM-1s-1, indicating higher catalytic efficiency than previously reported APAP amidases. Molecular dynamics simulations and site-directed mutagenesis confirmed that a Ser161-Ser185-Lys82 triad constitutes the catalytic center driving amide cleavage. These findings provide mechanistic insights into bacterial APAP biodegradation and highlight the practical application potential of strain DL27 and AdA.