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Vanadium-dependent bromoperoxidase in a marine Synechococcus /

  • Author(s): Johnson, Todd Laurel
  • et al.
Abstract

Vanadium-dependent bromoperoxidase (VBPO) carries out the two-electron oxidation of halides using hydrogen peroxide to create a hypohalous acid-like intermediate, which then halogenates electron-rich organic molecules. While this enzyme is well-characterized in marine eukaryotic macroalgae, the activity and function of VBPO in prokaryotes remains vastly unexplored. A gene (sync_2681) encoding a putative VBPO was recently annotated in the genome of Synechococcus sp. CC9311, however the activity, function, and consequences of the expression of VBPO in cyanobacteria remained unknown. The first goal of this dissertation was to better characterize the activity of VBPO in CC9311, finding that the observed activity resulted from the single, expected gene product. One highly neglected aspect of studies of VBPO is the use of genetic manipulation to test natural physiological and ecological functions of this enzyme. Thus the second goal of this dissertation was to explore the function of VBPO in CC9311 through the creation of a mutant lacking a functional VBPO, then tracking activity under diverse conditions in coordination with global quantitative proteomics. The final goal of this dissertation was to explore the chemical consequences of the expression of VBPO in cyanobacteria, specifically measuring the production of halomethanes. VBPO has long been implicated in the production of polyhalogenated methanes, such as bromoform and dibromomethane through the use of eukaryotic algal protein extracts, however, this dissertation offers the first evidence that the VBPO in a marine cyanobacterium is responsible for the production of halogenated methanes in a laboratory setting

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