title: CHARACTERIZATION OF A FUNCTIONAL VANADIUM-DEPENDENT BROMOPEROXIDASE IN THE MARINE CYANOBACTERIUM SYNECHOCOCCUS SP. CC9311(1).
abstract: Vanadium-dependent bromoperoxidases (VBPOs) are characterized by the ability to oxidize halides using hydrogen peroxide. These enzymes are well-studied in eukaryotic macroalgae and are known to produce a variety of brominated secondary metabolites. Though genes have been annotated as VBPO in multiple prokaryotic genomes, they remain uncharacterized. The genome of the coastal marine cyanobacterium Synechococcus sp. CC9311 encodes a predicted VBPO (YP_731869.1, sync_2681), and in this study, we show that protein extracts from axenic cultures of Synechococcus possess bromoperoxidase activity, oxidizing bromide and iodide, but not chloride. In-gel activity assays of Synechococcus proteins separated using PAGE reveal a single band having VBPO activity. When sequenced via liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS), peptides from the band aligned to the VBPO sequence predicted by the open reading frame (ORF) sync_2681. We show that a VBPO gene is present in a closely related strain, Synechococcus sp. WH8020, but not other clade I Synechococcus strains, consistent with recent horizontal transfer of the gene into Synechococcus. Diverse cyanobacterial-like VBPO genes were detected in a pelagic environment off the California coast using PCR. Investigation of functional VBPOs in unicellular cyanobacteria may lead to discovery of novel halogenated molecules and a better understanding of these organisms' chemical ecology and physiology.
authors.affiliation: Scripps Institution of Oceanography, University of California San Diego, 8750 Biological Grade, La Jolla, California 92093-0202, USA.
authors.forename: Todd L
authors.initials: TL
authors.lastname: Johnson
authors.affiliation: Scripps Institution of Oceanography, University of California San Diego, 8750 Biological Grade, La Jolla, California 92093-0202, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Palenik
authors.affiliation: Scripps Institution of Oceanography, University of California San Diego, 8750 Biological Grade, La Jolla, California 92093-0202, USA.
authors.forename: Bianca
authors.initials: B
authors.lastname: Brahamsha
keywords: Synechococcus; cyanobacteria; horizontal gene transfer; specific activity; vanadium-dependent bromoperoxidase