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Hydrogen Peroxide Linked to Lysine Oxidase Activity Facilitates Biofilm Differentiation and Dispersal in Several Gram-Negative Bacteria

School of Biotechnology and Biomolecular Sciences and Centre for Marine Bio-Innovation, Biological Sciences Building, University of New South Wales, Kensington, Sydney, NSW 2052, Australia.
Journal of bacteriology (Impact Factor: 2.69). 09/2008; 190(15):5493-501. DOI: 10.1128/JB.00549-08
Source: PubMed

ABSTRACT The marine bacterium Pseudoalteromonas tunicata produces an antibacterial and autolytic protein, AlpP, which causes death of a subpopulation of cells during biofilm formation and mediates differentiation, dispersal, and phenotypic variation among dispersal cells. The AlpP homologue (LodA) in the marine bacterium Marinomonas mediterranea was recently identified as a lysine oxidase which mediates cell death through the production of hydrogen peroxide. Here we show that AlpP in P. tunicata also acts as a lysine oxidase and that the hydrogen peroxide generated is responsible for cell death within microcolonies during biofilm development in both M. mediterranea and P. tunicata. LodA-mediated biofilm cell death is shown to be linked to the generation of phenotypic variation in growth and biofilm formation among M. mediterranea biofilm dispersal cells. Moreover, AlpP homologues also occur in several other gram-negative bacteria from diverse environments. Our results show that subpopulations of cells in microcolonies also die during biofilm formation in two of these organisms, Chromobacterium violaceum and Caulobacter crescentus. In all organisms, hydrogen peroxide was implicated in biofilm cell death, because it could be detected at the same time as the killing occurred, and the addition of catalase significantly reduced biofilm killing. In C. violaceum the AlpP-homologue was clearly linked to biofilm cell death events since an isogenic mutant (CVMUR1) does not undergo biofilm cell death. We propose that biofilm killing through hydrogen peroxide can be linked to AlpP homologue activity and plays an important role in dispersal and colonization across a range of gram-negative bacteria.

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    • "Mai-Prochnow et al. [26] have suggested that H2O2 allows to (directly or indirectly) kill a subpopulation of cells and increase in DNA damage and mutation frequency of the remaining live cells and shown that high CAT activity can prevent penetration of hydrogen peroxide into biofilms of Pseudomonas aeruginosa at a concentration of 50 mM. In our work, it was observed that biofilm development is influenced by the production of oxidants metabolites and the levels of antioxidant defenses, which can be variable in different environmental conditions. "
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    • "and it is not possible to make predictions about their actual enzymatic activities. For instance, two proteins from Chromobacterium violaceum NP_902938 and Caulobacter crescentus NP_419374 belonging to the same group but with lower sequence identity to LodA (29.5% and 23.1%, respectively) also play a role in biofilm development and differentiation which is mediated by hydrogen peroxide production, although their actual enzymatic activity was not described (Mai-Prochnow et al. 2008). Preliminary studies in our lab have failed to detect either GO or lysine oxidase in C. crescentus or C. violaceum (J. "
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    ABSTRACT: A novel enzyme with lysine-epsilon oxidase activity was previously described in the marine bacterium Marinomonas mediterranea. This enzyme differs from other l-amino acid oxidases in not being a flavoprotein but containing a quinone cofactor. It is encoded by an operon with two genes lodA and lodB. The first one codes for the oxidase, while the second one encodes a protein required for the expression of the former. Genome sequencing of M. mediterranea has revealed that it contains two additional operons encoding proteins with sequence similarity to LodA. In this study, it is shown that the product of one of such genes, Marme_1655, encodes a protein with glycine oxidase activity. This activity shows important differences in terms of substrate range and sensitivity to inhibitors to other glycine oxidases previously described which are flavoproteins synthesized by Bacillus. The results presented in this study indicate that the products of the genes with different degrees of similarity to lodA detected in bacterial genomes could constitute a reservoir of different oxidases.
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    • "Enzymes secreted by the bacteria modify EPS composition in response to changes in nutrient availability (Sauer et al. 2004; Gjermansen et al. 2005), thereby tailoring biofilm architecture to the specific environment (Sauer et al. 2004; Ma et al. 2009). Thus, the structural components of the matrix give rise to a highly hydrated, robust structure with high tensile strength that keeps bacteria in close proximity, enabling intimate cell-to-cell interactions and DNA exchange (Flemming and Wingender 2010; Koo et al. 2010), while protecting the biomass from desiccation , predation, oxidizing molecules, radiation , and other damaging agents (Walters et al. 2003; Jefferson et al. 2005; Mai-Prochnow et al. 2008; Flemming and Wingender 2010). The resilient nature of biofilms is also partly attributed to the presence of environmental gradients within the biomass, which give rise to community " division of labor " with subpopulations of bacteria showing differential gene expression in response to local nutrient and oxygen availability (Lewis 2005; Domka et al. 2007). "
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