FN Archimer Export Format
PT J
TI Cu transport and complexation by the marine diatom Phaeodactylum tricornutum: Implications for trace metal complexation kinetics in the surface ocean
BT 
AF González-Dávila, Melchor
   Maldonado, Maria T.
   González, Aridane G.
   Guo, Jian
   González-Santana, David
   Martel, Antera
   Santana-Casiano, J. Magdalena
AS 1:1;2:2;3:1;4:2;5:1;6:3;7:1;
FF 1:;2:;3:;4:;5:;6:;7:;
C1 Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain
   Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia Vancouver, BC, Canada
   Banco Español de Algas, Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain
C2 UNIV LAS PALMAS GRAN CANARIA, SPAIN
   UNIV BRITISH COLUMBIA, CANADA
   UNIV LAS PALMAS GRAN CANARIA, SPAIN
IF 9.8
TC 0
UR https://archimer.ifremer.fr/doc/00877/98859/108557.pdf
   https://archimer.ifremer.fr/doc/00877/98859/109296.docx
LA English
DT Article
DE ;Copper;adsorption kinetics;Cu transport;complexation;diatoms;Phaeodactylum tricornutum;Cu uptake
AB Elucidating whether dissolved Cu uptake is kinetically or thermodynamically controlled, and the effects of speciation on Cu transport by phytoplankton will allow better modeling of the fate and impact of dissolved Cu in the ocean. To address these questions, we performed Cu physiological and physicochemical experiments using the model diatom, Phaeodactylum tricornutum, grown in natural North Atlantic seawater (0.44 nM Cu). Using competitive ligand equilibration-cathodic stripping voltammetry (CLE-CSV), we measured two organic ligand types released by P. tricornutum to bind Cu (L1 and L2) at concentrations of ~0.35 nM L1 and 1.3 nM L2. We also established the presence of two putative Cu-binding sites at the cell surface of P. tricornutum (S1 and S2) with log K differing by ~5 orders of magnitude (i.e., 12.9 vs. 8.1) and cell surface densities by 9-fold. Only the high-affinity binding sites, S1, exhibit reductase activity. Using voltammetric kinetic measurements and a theoretical kinetic model, we calculated the forward and dissociation rate constants of L1 and S1. Complementary 67Cu uptake experiments identified a high- and a low-affinity Cu uptake system in P. tricornutum, with half-saturation constant (Km) of 154 nM and 2.63 μM dissolved Cu, respectively. In the P. tricornutum genome, we identified a putative high-affinity Cu transporter (PtCTR49224) and a putative ZIP-like, low-affinity Cu transporter (PtZIP49400). PtCTR49224 has high homology to Homo sapiens hCTR1, which depending on the accessibility to extracellular reducing agents, the hCTR1 itself is involved in the reduction of Cu2+ to Cu+ before internalization. We combined these physiological and physicochemical data to calculate the rate constants for the internalization of Cu, and established that while the high-affinity Cu uptake system (S1) is borderline between a kinetically or thermodynamically controlled system, the low-affinity Cu transporters, S2, is thermodynamically-controlled. We revised the inverse relationship between the concentrations of inorganic complexes of essential metals (i.e., Ni, Fe, Co, Zn, Cd, Mn and Cu) in the mixed layer and the formation rate constant of metal transporters in phytoplankton, highlighting the link between the chemical properties of phytoplankton metal transporters and the availability and speciation of trace metals in the surface ocean. 
PY 2024
PD APR
SO Science of The Total Environment
SN 0048-9697
PU Elsevier BV
VL 919
DI 10.1016/j.scitotenv.2024.170752
ID 98859
ER

EF