Peritonitis due to Brevibacterium otitidis in a patient undergoing continuous ambulatory peritoneal dialysis.
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Brevibacterium otitidis is a coryneform rod and, as far as is known, is isolated only from infected ears. We report the first known case of peritonitis caused by B. otitidis in a patient undergoing continuous ambulatory peritoneal dialysis. (+info)
Diversity of L-methionine catabolism pathways in cheese-ripening bacteria.
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Enzymatic activities that could be involved in methanethiol generation in five cheese-ripening bacteria were assayed, and the major sulfur compounds produced were identified. L-Methionine and alpha-keto-gamma-methyl-thio-butyric acid demethiolating activities were detected in whole cells and cell extracts (CFEs) of all the bacteria tested. No L-methionine deaminase activity could be detected in any of the ripening bacteria and L-methionine aminotransferase was detected in CFEs of Brevibacterium linens, Micrococcus luteus, and Corynebacterium glutamicum. The results suggest that several pathways for L-methionine catabolism probably coexist in these ripening bacteria. (+info)
Cholesterol oxidase from Brevibacterium sterolicum. The relationship between covalent flavinylation and redox properties.
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Brevibacterium sterolicum possesses two forms of cholesterol oxidase, one containing noncovalently bound FAD, the second containing a FAD covalently linked to His(69) of the protein backbone. The functional role of the histidyl-FAD bond in the latter cholesterol oxidase was addressed by studying the properties of the H69A mutant in which the FAD is bound tightly, but not covalently, and by comparison with native enzyme. The mutant retains catalytic activity, but with a turnover rate decreased 35-fold; the isomerization step of the intermediate 3-ketosteroid to the final product is also preserved. Stabilization of the flavin semiquinone and binding of sulfite are markedly decreased, this correlates with a lower midpoint redox potential (-204 mV compared with -101 mV for wild-type). Reconstitution with 8-chloro-FAD led to a holoenzyme form of H69A cholesterol oxidase with a midpoint redox potential of -160 mV. In this enzyme form, flavin semiquinone is newly stabilized, and a 3.5-fold activity increase is observed, this mimicking the thermodynamic effects induced by the covalent flavin linkage. It is concluded that the flavin 8alpha-linkage to a (N1)histidine is a pivotal factor in the modulation of the redox properties of this cholesterol oxidase to increase its oxidative power. (+info)
Oxygen access to the active site of cholesterol oxidase through a narrow channel is gated by an Arg-Glu pair.
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Cholesterol oxidase is a monomeric flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. Two forms of the enzyme are known, one containing the cofactor non-covalently bound to the protein and one in which the cofactor is covalently linked to a histidine residue. The x-ray structure of the enzyme from Brevibacterium sterolicum containing covalently bound FAD has been determined and refined to 1.7-A resolution. The active site consists of a cavity sealed off from the exterior of the protein. A model for the steroid substrate, cholesterol, can be positioned in the pocket revealing the structural factors that result in different substrate binding affinities between the two known forms of the enzyme. The structure suggests that Glu(475), located at the active site cavity, may act as the base for both the oxidation and the isomerization steps of the catalytic reaction. A water-filled channel extending toward the flavin moiety, inside the substrate-binding cavity, may act as the entry point for molecular oxygen for the oxidative half-reaction. An arginine and a glutamate residue at the active site, found in two conformations are proposed to control oxygen access to the cavity from the channel. These concerted side chain movements provide an explanation for the biphasic mode of reaction with dioxygen and the ping-pong kinetic mechanism exhibited by the enzyme. (+info)
Digested bacterial cell powder (DBCP) as a source of reduced-form folates for pigs: use of a trimethoprim-resistant strain and the bioavailability of folates in DBCP.
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The production of digested bacterial cell powder (DBCP) as a source of reduced-form folates for pigs was studied. Trimethoprim-resistant mutants of Brevibacterium lactofermentum ATCC 13869 accumulated a significantly higher amount of the reduced form of folate in the cells than the wild-type strain. DBCPs were prepared from the resistant mutant strain and the wild-type strain. The utilization of the reduced-form of folate in DBCP was evaluated by measuring the plasma folate level after orally administering DBCP to Gottingen minipigs. The folates in both DBCPs proved to have equally high bioavailability in the pigs. (+info)
The involvement of CD14 in the activation of human monocytes by peptidoglycan monomers.
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BACKGROUND: Cell-wall components of Gram-positive and Gram-negative bacteria induce the production of cytokines in human peripheral blood mononuclear cells. These cytokines are the main mediators of local or systemic inflammatory reaction that can contribute to the development of innate immunity. AIMS: This study was performed to analyze the involvement of CD14 molecule in the activation of human monocytes by peptidoglycan monomer (PGM) obtained by biosynthesis from culture fluid of penicillin-treated Brevibacterium divaricatum NRLL-2311. METHODS: Cytokine release of interleukin (IL)-1, IL-6 and tumor necrosis factor-alpha from human monocytes via soluble CD14 (sCD14) or membrane-associated (mCD14) receptor using anti-CD14 monoclonal antibody (MEM-18) or lipid A structure (compound 406) was measured in bioassays. RESULTS: The results demonstrated that PGM in the presence of human serum might induce the monokine release in a dose-dependent manner. The addition of sCD14 at physiologic concentrations enhanced the PGM-induced monokine release, while the monokine inducing capacity of PGM in the presence of sCD14 was inhibited by MEM-18. Effects of PGM were also blocked by glycolipid, compound 406, suggesting the involvement of binding structures similar to those for lipopolysaccharide. CONCLUSION: Activation of human monocytes by PGM involves both forms of CD14 molecule, sCD14 and mCD14. (+info)
Purification and characterization of L-2,3-butanediol dehydrogenase of Brevibacterium saccharolyticum C-1012 expressed in Escherichia coli.
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The L-2,3-butanediol dehydrogenase produced in E. coli JM109/pLBD2-CTC was purified by 5 steps. The molecular mass of this enzyme was estimated at 110 kDa and the subunit was measured to be 30 kDa. The L-BDH had some differences from the BDHs from other sources in substrate specificity, pI value, pH stability, effects of divalent cations, and organic acids. (+info)
Brevibacterium paucivorans sp. nov., from human clinical specimens.
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Seven isolates from various human body sites displayed general chemotaxonomic and phenotypic characteristics of the genus Brevibacterium. This was corroborated by the 16S rRNA gene sequence analysis of strain CF62T, showing a sequence similarity of 99% to Brevibacterium mcbrellneri. However, DNA-DNA hybridization, a peculiar amino acid content of the cell wall and some phenotypic properties clearly suggested that these strains belong to a new species, for which the name Brevibacterium paucivorans sp. nov. is proposed. The type strain of B. paucivorans is CF62T (= DSM 13657T = LMG 19814T). The DNA G+C content of the type strain is 55.8 mol%. (+info)