Structural insights for enhanced ROS detoxification of eKatE, a recently identified catalase in atypical E. coli

Abstract

Catalase is a crucial enzyme that protects organisms from reactive oxygen species (ROS)-induced oxidative stress. eKatE, a recently identified catalase variant in commensal Escherichia coli (E. coli), significantly contributes to infectious diseases and inflammatory bowel disease (IBD). Here, we enhanced the ROS detoxification capacity of eKatE, distinguishing it from the typical E. coli catalase KatE. eKatE forms a tetramer with a well-folded N-terminal arm and a dual conformation of the long R173eKatE, in contrast to the disordered N terminus and A173KatE of KatE. Additionally, a V256-induced bottleneck in the major channel enhances the sensitivity of eKatE to H2O2, differing from A256KatE. Furthermore, K294eKatE flipped inside to shield the major and lateral channels more effectively than K294KatE. Covalent bonding of C392eKatE to the essential Y415 increased the catalytic activity compared with that of H392KatE. Finally, the electrostatic potential surface of the eKatE tetramers differed from those of KatE, particularly near the substrate-inlet and product-outlet regions. These findings on the improved catalytic capacity of eKatE highlight its potential application in mitigating ROS-related diseases and treating IBD.