Structural insights for enhanced <scp>ROS</scp> detoxification of <scp>eKatE</scp> , a recently identified catalase in atypical <i>E. coli</i>

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 R173^eKatE, in contrast to the disordered N terminus and A173^KatE of KatE. Additionally, a V256-induced bottleneck in the major channel enhances the sensitivity of eKatE to H₂O₂, differing from A256^KatE. Furthermore, K294^eKatE flipped inside to shield the major and lateral channels more effectively than K294^KatE. Covalent bonding of C392^eKatE to the essential Y415 increased the catalytic activity compared with that of H392^KatE. 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.