PHYLOGENETIC-RELATIONSHIPS AMONG PROKARYOTIC AND EUKARYOTIC CATALASES

Seventy-four catalase protein sequences, including 29 bacterial, 8 fun gal, 7 animal, and 30 plant sequences, were compiled, and 70 were used for phylogenetic reconstruction. The core of the resulting tree revea led unique, separate groups of plant and animal catalases, two groups of fungal catalases, and three groups of bacterial catalases. The only overlap of kingdoms occurred within one branch and involved fungal an d bacterial large-subunit enzymes. The other fungal branch was closely linked to the group of animal enzymes. Group I bacterial catalases we re more closely related to the plant enzymes and contained such divers e taxa as the Gram-positive Listeria seeligeri, Dein-ocococcus radiodu rans, and gamma-proteobacteria. Group III bacterial sequences were mor e closely related to fungal and animal sequences and included enzymes from a broad range of bacteria including high-and low-GC Gram positive s, proteobacteria, and a bacteroides species. Group TI was composed of large-subunit catalases from diverse sources including Gram positives (low-GC Bacilli and high-GC Mycobacteria), proteobacteria, and specie s of the filamentous fungus Aspergillus. These data can be interpreted in terms of two gene duplication events that produced a minimum of th ree catalase gene family members that subsequently evolved in response to environmental demands. Horizontal gene transfer may have been resp onsible for the group II mixture of bacterial and fungal large-subunit catalases.