Copper uptake mechanism of Arabidopsis thaliana high-affinity COPT transporters
Copper (Cu) is an essential plant micronutrient. Under scarcity, Cu 2+ is reduced to Cu + and taken up through specific high-affinity transporters (COPTs). In Arabidopsis , the COPT family consists of six members, either located at the plasma membrane (COPT1, COPT2, and COPT6) or in internal membran...
Saved in:
Published in | Protoplasma Vol. 256; no. 1; pp. 161 - 170 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Vienna
Springer Vienna
01.01.2019
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Copper (Cu) is an essential plant micronutrient. Under scarcity, Cu
2+
is reduced to Cu
+
and taken up through specific high-affinity transporters (COPTs). In
Arabidopsis
, the COPT family consists of six members, either located at the plasma membrane (COPT1, COPT2, and COPT6) or in internal membranes (COPT3 and COPT5). Cu uptake by COPT proteins has been mainly assessed through complementation studies in corresponding yeast mutants, but the mechanism of this transport has not been elucidated. To test whether Cu is incorporated by an electrogenic mechanism, electrophysiological changes induced by Cu addition were studied in
Arabidopsis thaliana
. Mutant (T-DNA insertion mutants,
copt2–1
and
copt5–2
) and overexpressing lines (
COPT1
OE
and
COPT5
OE
) with altered expression of
COPT
transporters were compared to wild-type plants. No significant changes of the membrane potential (E
m
) were detected, regardless of genotype or Cu concentration supplied. In contrast, membrane depolarization was detected in response to iron supply in both wild-type and in mutant or transgenic plants. Similar results were obtained for trans-plant potentials (TPP). GFP fusions of the plasma membrane COPT2 and the internal COPT5 transporters were expressed in
Xenopus laevis
oocytes to potentiate Cu uptake signals, and the cRNA-injected oocytes were tested for electrical currents upon Cu addition using two-electrode voltage clamp. Results with oocytes confirmed those obtained in plants. Cu accumulation in injected oocytes was measured by ICP-OES, and a significant increase in Cu content with respect to controls occurred in oocytes expressing
COPT2:GFP
. The possible mechanisms driving this transport are discussed in this manuscript. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0033-183X 1615-6102 |
DOI: | 10.1007/s00709-018-1286-1 |