Abstract

Redox-based chemical warfare is a primary driver of microbial community assembly. Here, we show that the predatory bacterium Myxococcus xanthus employs a spatial division of labor between two inducible monofunctional catalases, mxKatB and mxKatE, to overcome prey-derived hydrogen peroxide (H2O2). Quantitative transcript analysis revealed distinct regulatory specificities: mxkatB was the dominant transcriptional responder to exogenous H2O2, whereas mxkatE was preferentially induced by UV irradiation. Biochemical analyses demonstrated strict compartmentalization of enzymatic activity. mxKatE functioned intracellularly, consistent with a role in mitigating endogenous genotoxic stress. In contrast, mxKatB, which harbors an N-terminal Sec-dependent signal peptide, was exclusively localized to the extracellular milieu. Targeted gene deletions corroborated these non-redundant physiological roles. {Delta}katE mutant exhibited severe growth defects and heightened sensitivity to UV and H2O2 yet retained full predation proficiency. Conversely, {Delta}katB mutant displayed unaltered vegetative fitness but were severely impaired in prey lysis due to oxidative inactivation of secreted bacteriolytic enzymes. Failure of cross-complementation confirmed that spatial localization, rather than catalytic capacity, dictates enzyme function. Our findings establish that M. xanthus deploys an extracellular catalase shield to protect its exoenzyme arsenal from prey-derived oxidants. This spatial specialization of antioxidant defenses represents a sophisticated strategy that directly determines the outcome of bacterial predation and shapes interspecies interactions within microbial communities.