Abstract
Catalases play a key role in the defense against oxidative stress in bacteria by catalyzing the decomposition of H2O2. In addition, catalases are also involved in multiple cellular processes, such as cell development and differentiation, as well as metabolite production. However, little is known about the abundance, diversity, and distribution of catalases in bacteria. In this study, we systematically surveyed and classified the homologs of three catalase families from 2,634 bacterial genomes. It was found that both of the typical catalase and Mn-catalase families could be divided into distinct groups, while the catalase-peroxidase homologs formed a tight family. The typical catalases are rich in all the analyzed bacterial phyla except Chlorobi, in which the catalase-peroxidases are dominant. Catalase-peroxidases are rich in many phyla, but lacking in Deinococcus-Thermus, Spirochetes, and Firmicutes. Mn-catalases are found mainly in Firmicutes and Deinococcus-Thermus, but are rare in many other phyla. Given the fact that catalases were reported to be involved in secondary metabolite biosynthesis in several Streptomyces strains, the distribution of catalases in the genus Streptomyces was given more attention herein. On average, there are 2.99 typical catalases and 0.99 catalase-peroxidases in each Streptomyces genome, while no Mn-catalases were identified. To understand detailed properties of catalases in Streptomyces, we characterized all the five typical catalases from S. rimosus ATCC 10970, the oxytetracycline-producing strain. The five catalases showed typical catalase activity, but possessed different catalytic properties. Our findings contribute to the more detailed classification of catalases and facilitate further studies about their physiological roles in secondary metabolite biosynthesis and other cellular processes, which might facilitate the yield improvement of valuable secondary metabolites in engineered bacteria.
Highlights
Reactive oxygen species (ROS) are generated in the O2 reduction process, including superoxide anion (O2·−), hydrogen peroxide (H2O2), and hydroxyl radical (OH·) (Montibus et al, 2015; Johnson and Hug, 2019; Kim et al, 2019)
Our study has provided the basis for further investigation of bacterial catalases to better understand their physiological roles in various cellular processes
An early phylogenetic analysis of 20 typical catalases suggested that small subunit typical catalases of animal and fungi were derived from one ancestor, while those catalases of plant originated from another ancestor
Summary
Reactive oxygen species (ROS) are generated in the O2 reduction process, including superoxide anion (O2·−), hydrogen peroxide (H2O2), and hydroxyl radical (OH·) (Montibus et al, 2015; Johnson and Hug, 2019; Kim et al, 2019). These ROS can cause the oxidative damage of cellular macromolecules and lead to dysfunction of cells (Montibus et al, 2015; Johnson and Hug, 2019). Previous studies proposed that the reduction process involved the transfer of a hydride ion from H2O2 to compound I (Fita and Rossmann, 1985; Kato et al, 2004; Alfonso-Prieto et al, 2012), while the metadynamics simulation analysis suggested that the transfer of one hydrogen atom from H2O2 to compound I occurred first, followed by another reduction reaction (Kato et al, 2004; Alfonso-Prieto et al, 2009, 2012)
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