TY - JOUR
T1 - Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry
AU - Kuepper, Frithjof C.
AU - Carpenter, Lucy J.
AU - McFiggans, Gordon B.
AU - Palmer, Carl J.
AU - Waite, Tim J.
AU - Boneberg, Eva-Maria
AU - Woitsch, Sonja
AU - Weiller, Markus
AU - Abela, Rafael
AU - Grolimund, Daniel
AU - Potin, Philippe
AU - Butler, Alison
AU - Luther, George W.
AU - Kroneck, Peter M. H.
AU - Meyer-Klaucke, Wolfram
AU - Feiters, Martin C.
PY - 2008/5/13
Y1 - 2008/5/13
N2 - Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodocarbons in the coastal atmosphere. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic antioxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface and in the apoplast, iodide detoxifies both aqueous oxidants and ozone, the latter resulting in the release of high levels of molecular iodine and the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human blood cells.
AB - Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodocarbons in the coastal atmosphere. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic antioxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface and in the apoplast, iodide detoxifies both aqueous oxidants and ozone, the latter resulting in the release of high levels of molecular iodine and the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human blood cells.
KW - algae
KW - laminaria
KW - X-ray absorption spectroscopy
KW - Cathodic stripping square wave voltammetry
U2 - 10.1073/pnas.0709959105
DO - 10.1073/pnas.0709959105
M3 - Article
SN - 0027-8424
VL - 105
SP - 6954
EP - 6958
JO - PNAS
JF - PNAS
IS - 19
ER -