Bacillus subtilis Vegetative Catalase Is an Extracellular Enzyme

Abstract

Strong catalase activity was secreted by Bacillus subtilis cells during stationary growth phase in rich medium but not in sporulation-inducing medium. N-terminal sequencing indicated that the secreted activity was due to the vegetative catalase KatA, previously considered an endocellular enzyme. Extracellular catalase protected B. subtilis cells from oxidative assault. The molecular response to oxidative stress has been extensively studied as it occurs in both gram-negative (6, 17) and gram-positive (18) bacteria. Exposure of aerobically grown Escherichia coli cells to hydrogen peroxide results in the coordinate expression of nine genes that compose the oxyR global regulon (17). A member of this regulon is katG, the structural gene for hydrogen peroxidase I, an H 2 O 2-inducible catalase. The katE gene, coding for the second catalase, HPII, is expressed when cells enter stationary phase and is under the transcriptional control of a specific sigma factor (s) of RNA polymerase (12). For Bacillus subtilis only a single catalase is found in cell extracts during vegetative growth (KatA). Expression of its structural gene, katA, is H 2 O 2 and growth phase inducible (18). A second catalase is found only after the onset of sporulation (13). Catalases and peroxidases in a number of microorganisms, including Haemophilus influenzae (1, 2), Mycobacterium tuberculosis (10), and Streptomyces viridosporus (16), have been studied. These enzymes play important roles in several microbial processes also independent of oxidative stress. Microbial peroxidases are involved in the oxidation of a large number of aromatic compounds, including recalcitrant substances (14). Catalases of pathogenic bacteria, like Listeria monocytogenes, H. influenzae, and Helicobacter pylori, are considered potential virulence factors which may counteract the oxygen-dependent defense mechanisms of infected phagocytes (1, 8, 15). It is thought that during food fermentation catalases from lactobacilli decrease hydrogen peroxide accumulation, which would severely affect the sensory quality of products (11). Catalases from Aspergillus niger are used to eliminate from milk hydrogen peroxide either endogenously produced or added in the process of cold pasteurization. We have found a vegetative catalase activity secreted by B. subtilis cells during the stationary growth phase. We report here that this activity is due to KatA and that its secretion is essential to ensure complete protection of B. subtilis cells against oxidative stress. The finding that KatA is a secreted enzyme will facilitate its purification and the study of its mechanism of action, therefore enhancing interest in B. subtilis catalase. KatA, the vegetative catalase of B. subtilis, is secreted during the stationary growth phase. Filter-sterilized cell-free super

The Periplasmic, Group III Catalase ofVibrio fischeriIs Required for Normal Symbiotic Competence and Is Induced Both by Oxidative Stress and by Approach to Stationary Phase

“…Subcellular localization of the catalase protein. Although many of the well-characterized bacterial catalases are typically present in the cytoplasm, some, such as the KatA catalase from B. subtilis (8,29), are exported. Because the V. fischeri enzyme has a high degree of identity with the B. subtilis catalase, and because a secreted catalase might be of particular value if the light organ environment were a significant source of reactive oxygen species, we investigated whether the catalase protein from V. fischeri was exported.…”

Characterization of the Starvation-Survival Response of Staphylococcus aureus

“…This catalase appears to be synthesized throughout growth, since both exponential-phase and longterm-starved culture supernatants conferred resistance to hydrogen peroxide. Such an extracellular catalase has been identified in Bacillus subtilis and was found to protect cells from a hydrogen peroxide challenge (28).…”

A novel strategy for protein production using non-classical secretion pathway in Bacillus subtilis

“…Proteins involved in metabolism of amino acids, RocA and RocF, were initially found by Antelman et al [ 20 ] to be non-classically secreted, but only RocF was later identified by Vitikainen et al [ 19 ]. The vegetative catalase KatA that was previously considered to be an intracellular enzyme due to the absence of a signal peptide, was later found to be localized extracellularly when B. subtilis was grown in the rich medium (about 56 % of the total KatA) [ 21 ]. Of course, the detection of non-classically secreted proteins in the extracellular environment could obviously be attributed to cell lysis.…”