Different regulation of haloperoxidation during agar oligosaccharide-activated defence mechanisms in two related red algae.

Weinberger, Florian , Coquempot, B., Forner, S., Morin, P., Kloareg, B. and Potin, P. (2007) Different regulation of haloperoxidation during agar oligosaccharide-activated defence mechanisms in two related red algae. Journal of Experimental Botany, 58 (15-16). pp. 4365-4372. DOI 10.1093/jxb/erm303.

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The related red seaweeds Gracilaria sp. from the eastern Mediterranean and Gracilaria chilensis from Chile were similar in their enzymatic inventory for halogenation. In both species, halogenation was dependent upon H(2)O(2) and thus driven by haloperoxidases. These could be inhibited with phosphate and reversibly inhibited with azide and were therefore apparently dependent upon vanadate. Both species generated in the first line bromoform and other brominated halocarbons. Gel electrophoresis under non-denaturating conditions demonstrated that both species expressed halogenating peroxidases. Elicitation of Gracilaria sp. with agar oligosaccharides resulted in marked increases in bromination, iodination, and chlorination. Production rates of volatile halocarbons and phenol red bromination both increased by a factor of eight, presumably due to increased availability for haloperoxidases of H(2)O(2) during the oxidative burst response. Elicitation of Gracilaria sp. also triggered a release of bromide ions through DIDS-sensitive anion channels, which allowed for some bromination in bromide-free medium. However, this effect was relatively limited. By contrast, agar oligosaccharide oxidation in G. chilensis did not increase halogenation. Obviously, agar oligosaccharide oxidation does not provide sufficient amounts of hypohalous acids for such increases, because it does not deliver H(2)O(2) at the active site of vanadium-dependent haloperoxidases. These results correlate with earlier findings that the agar oligosaccharide-elicited oxidative burst controls microorganisms while agar oligosaccharide oxidation does not.

Document Type: Article
Keywords: Benthic Ecology; Bromination; Gracilaria; halogenation; haloperoxidase; iodination; seaweed–microbe interactions
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1093/jxb/erm303
ISSN: 0022-0957
Projects: Future Ocean
Date Deposited: 24 Mar 2011 09:30
Last Modified: 10 Jul 2017 11:44
URI: http://oceanrep.geomar.de/id/eprint/11402

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