CATALASE OF THE LACTOBACILLACEAE

Protection of Bacillus larvae from Oxygen Toxicity with Emphasis on the Role of Catalase

Sporulation of Bacillus larvae NRRL B-3650 occurred only at aeration rates lower than those used for cultivation of most Bacillus species. One possible explanation for the requirement for a low level of aeration in B. larvae is that toxic forms of oxygen such as H(2)O(2) and superoxide are involved. The superoxide dismutase levels of strain B-3650 were similar to those of Bacillus subtilis 168 during sporulation, and no NADH peroxidase was present. Catalase activity was absent during exponential growth and first appeared near the start of the stationary phase. The catalase activity was 2,700 times less than that in B. subtilis 168 at the same stage of development. Therefore, the relative deficiency of catalase (and NADH peroxidase) might be the cause of the apparent O(2) toxicity. It was postulated that B. larvae might accumulate H(2)O(2) in the medium and exhibit more than normal sensitivity to H(2)O(2). Experimental results did not verify either postulate, but the possibilities of intracellular accumulation of H(2)O(2) and unusual sensitivity to endogenous H(2)O(2) were not excluded. The catalase present in early-stationary-phase cells was soluble, heat labile, and inhibited by cyanide, azide, and hydroxylamine. An increase in catalase activity also occurred at the time of appearance of refractile spores in both B. larvae NRRL B-3650 and B. subtilis 168. The level of catalase activity in strain B-3650 was 5,400 times less than that in B. subtilis 168 at this stage. In B. larvae, this second increase occurred primarily within the developing endospore. The activity in spore extracts was particulate, heat stable, and inhibited by hydroxylamine but not by azide or cyanide. Synthesis of catalase in B. larvae was unaffected by H(2)O(2), O(2), or glucose.

Oxidative Metabolism in Pediococcus pentosaceus III. Glucose Dehydrogenase System

Lee, Chin K. (North Carolina State of the University of North Carolina, Raleigh), and Walter J. Dobrogosz. Oxidative metabolism in Pediococcus pentosaceus. III. Glucose dehydrogenase system. J. Bacteriol. 90:653-660. 1965.-A method was developed for the purification of glucose dehydrogenase from Pediococcus pentosaceus Az-25-5. The procedures included treatments with protamine sulfate, ammonium sulfate, and heat in addition to acid precipitation, calcium phosphate adsorption and elution, and diethylaminoethyl-Sephadex column chromatography. The final preparation thus obtained was purified 255-fold and exhibited both similarities and dissimilarities to the same enzyme isolated from other sources. The enzyme is absolutely specific for nicotinamide adenine dinucleotide phosphate (NADP) as a cofactor, and oxidizes only glucose or its analogue 2-deoxyglucose via the following reversible reaction: beta-d-glucose + NADP right harpoon over left harpoon d-glucono-delta-lactone + NADPH(2) + H(+). K(m) values were 2.3 x 10(-2) for glucose and 2 x 10(-4) for NADP. Monovalent cations were required for stability of the enzyme and stimulated activity. The pH optimum was 7.0, and the equilibrium constant was determined to be 13.4 x 10(-7) at pH 6.4. Among the Lactobacillaceae, glucose dehydrogenase activity was found to be essentially limited to members of the genus Pediococcus. Studies on the enzymatic composition of P. pentosaceus viewed in conjunction with other available data led to the conclusion that this enzyme is not involved to any significant extent in the energy metabolism of this organism.

Identification of a non-haem catalase in Salmonella and its regulation by RpoS (sigmaS)

We report the identification and functional analysis of katN, a gene encoding a non-haem catalase of Salmonella enterica serotype Typhimurium. katN, which is not present in Escherichia coli, is located between the yciGFE and yciD E. coli homologues in the Salmonella genome. Its predicted protein product has a molecular weight of 31 826 Da and is similar to the Mn-catalases of Lactobacillus plantarum and Thermus spp. Its product, KatN, was visualized as a 37 kDa protein in E. coli maxicells. A KatN recombinant protein, containing six histidine residues at its C-terminus, was purified, and its catalase activity was observed on a non-denaturing polyacrylamide gel. KatN was also visualized by catalase activity gel staining of bacterial cell extracts. Its expression was shown to be regulated by growth phase and rpoS. Northern blotting indicated that kat forms an operon with the upstream yciGFE genes. A putative rpoS-regulated promoter was identified upstream of yciG. Southern blotting revealed that katN is conserved within Salmonella serovars. katN homologues were found in Pseudomonas aeruginosa, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae and Serratia marcescens. A katN mutation did not appear to affect the hydrogen peroxide (H2O2) response of Salmonella. However, the expression of katN increased the H2O2 resistance of unadapted cells in the exponential phase and of rpoS mutants in stationary phase. Thus, KatN may contribute to hydrogen peroxide resistance in Salmonella in certain environmental conditions.

Purification and cloning of a thermostable manganese catalase from a thermophilic bacterium

We have purified a heat-stable catalase from a thermophilic bacterium, Thermus species strain YS 8-13. The enzyme was purified 160-fold from crude cellular extracts and possessed a specific activity of 8000 units/mg at 65 degrees C. The purified enzyme displayed the highest activity at pH 7 to 10 and temperatures around 85 degrees C. The catalase was determined to be a manganese catalase, based on results from atomic absorption spectra and inhibition experiments using sodium azide. The enzyme was composed of six identical subunits of molecular weight 36,000. Amino acid sequences determined from the purified protein were used to design oligonucleotide primers, which were in turn used to clone the coding gene. The nucleotide sequence of a 1.4-kb fragment of Thermus sp. YS 8-13 genomic DNA containing a 909-bp open reading frame was determined. The gene encoded a 302-residue polypeptide of deduced molecular weight 33,303. The deduced amino acid sequence displayed a region-specific homology with the sequences of the manganese catalase from a mesophilic organism, Lactobacillus plantarum.

Inactivation and reactivation of manganese catalase: oxidation-state assignments using X-ray absorption spectroscopy

The oxidation states of the Mn atoms in three derivatives of Mn catalase have been characterized using a combination of X-ray absorption near-edge structure (XANES) and EPR spectroscopies. The as-isolated enzyme has an average oxidation state of Mn(III) and contains a Mn(III) form, together with a reduced Mn(II) form and a variable amount (10-25%) of a Mn(III)/Mn(IV) mixed-valence derivative. Treatment with NH2OH rapidly reduces the majority of the enzyme to a Mn(II) derivative with no loss of activity. Inactivation by treatment with NH2OH + H2O2 converts all of the enzyme to a mixed-valence Mn(III)/Mn(IV) form. The inactive, mixed-valence derivative can be completely reactivated by long-term (greater than 1 h) anaerobic incubation with NH2OH, giving a reduced Mn(II)/Mn(II) derivative. These data suggest a catalytic model in which the enzyme cycles between a reduced Mn(II)/Mn(II) state and an oxidized Mn(III)/Mn(III) state.

Prevalence of hydrogen peroxide-producing Lactobacillus species in normal women and women with bacterial vaginosis

A predominance of Lactobacillus species in the vaginal flora is considered normal. In women with bacterial vaginosis, the prevalence and concentrations of intravaginal Gardnerella vaginalis and anaerobes are increased, whereas the prevalence of intravaginal Lactobacillus species is decreased. Because some lactobacilli are known to produce hydrogen peroxide (H2O2), which can be toxic to organisms that produce little or no H2O2-scavenging enzymes (e.g., catalase), we postulated that an absence of H2O2-producing Lactobacillus species could allow an overgrowth of catalase-negative organisms, such as those found among women with bacterial vaginosis. In this study, H2O2-producing facultative Lactobacillus species were found in the vaginas of 27 (96%) of 28 normal women and 4 (6%) of 67 women with bacterial vaginosis (P less than 0.001). Anaerobic Lactobacillus species (which do not produce hydrogen peroxide) were isolated from 24 (36%) of 67 women with bacterial vaginosis and 1 (4%) of 28 normal women (P less than 0.001). The production of H2O2 by Lactobacillus species may represent a nonspecific antimicrobial defense mechanism of the normal vaginal ecosystem.

Characterization of a manganese-containing catalase from the obligate thermophile Thermoleophilum album

A manganese-containing catalase has been characterized from Thermoleophilum album NM, a gram-negative aerobic bacterium obligate for thermophily and n-alkane substrates. The level of catalase in cells was increased about ninefold by growth in the presence of paraquat (2.5 microM), a superoxide-generating toxicant. Superoxide dismutase levels were unaffected by this compound. The enzyme was purified from cultures grown in the presence of paraquat to greater than 95% homogeneity and had an Mr of 141,000. The enzyme was composed of four subunits, and each had an Mr of 34,000. There were 1.4 +/- 0.4 atoms of manganese present per subunit. The catalase had a Km for hydrogen peroxide of 15 mM and a Vmax of 11 mM/mg. Peroxidase activity, as measured with p-phenylenediamine, copurified with the catalase. Inhibitors of heme-catalase were weak inhibitors of the T. album enzyme. The optimum pH for catalase activity was 8 to 9. The enzyme was stable from pH 6.5 to 11 and retained activity at assay temperatures from 25 to 80 degrees C. The catalase was stable for 24 h of incubation at 60 degrees C.

Functional significance of manganese catalase in Lactobacillus plantarum

A strain of Lactobacillus plantarum which was unable to produce manganese (Mn)catalase (ATCC 8014) grew somewhat more rapidly and to a slightly higher plateau density than did an Mn catalase-positive strain (ATCC 14421), and this was the case during aerobic or anaerobic growth. However, when maintenance of viability was measured during the stationary phase of the growth cycle, the advantage provided by Mn catalase was obvious. Thus, the viability of ATCC 14431 was undiminished over 21 h of aerobic incubation, during the stationary phase, whereas that of ATCC 8014 decreased by seven orders of magnitude. Addition of catalase to the medium or growth in the presence of hemin, which allows catalase synthesis, protected ATCC 8014 against this loss of viability. Suppression of Mn catalase within ATCC 14431 by treatment with NH2OH caused the cells to lose viability when exposed to 4 mM H2O2.

Distribution and Characteristics of the Catalases of Lactobacillaceae

Johnston , M. A. (Cornell University, Ithaca, N.Y.), and E. A. Delwiche . Distribution and characteristics of the catalases of Lactobacillaceae. J. Bacteriol. 90: 347–351. 1965.—Certain strains of lactobacilli and pediococci incorporated hematin during growth, with the concomitant formation of cyanide- and azide-sensitive catalase. Three of five strains of lactobacilli and five of 25 strains of pediococci were capable of this biosynthesis. The pediococci required the heme component of blood, whereas the lactobacilli could incorporate the heme component in the form of purified and solubilized hemin or from blood. In all cases where inhibitor-sensitive enzyme was produced, it was accompanied by the production of inhibitor-insensitive enzyme. In the absence of hematin, only insensitive enzyme was obtained. Two catalase-positive strains of Streptococcus faecalis were found incapable of the synthesis of a heme-type enzyme, as was one member of the genus Leuconostoc . Iron and manganese in the growth medium stimulated the production of the insensitive catalase, but significant quantities of these metals could not be found in a purified enzyme preparation obtained from Lactobacillus plantarum . Aeration had little or no effect on growth, but it consistently doubled the amount of cyanide- and azide-resistant catalase. By means of conventional enzyme fractionation techniques, it was possible to separate the two different enzymes present in the cell-free extract of a strain of Pediococcus homari which had been grown in the presence of blood.