SLC41A1 is a novel mammalian Mg2+ carrier.
The molecular biology of mammalian magnesium transporters and their interrelations in cellular magnesium homeostasis are largely unknown. Recently, the mouse SLC41A1 protein was suggested to be a candidate magnesium transporter with channel-like properties when overexpressed in Xenopus laevis oocytes. Here, we demonstrate that human SLC41A1 overexpressed in HEK293 cells forms protein complexes and locates to the plasma membrane without, however, giving rise to any detectable magnesium currents during whole cell patch clamp experiments. Nevertheless, in a strain of Salmonella enterica exhibiting disruption of all three distinct magnesium transport systems (CorA, MgtA, and MgtB), overexpression of human SLC41A1 functionally substitutes these transporters and restores the growth of the mutant bacteria at magnesium concentrations otherwise non-permissive for growth. Thus, we have identified human SLC41A1 as being a bona fide magnesium transporter. Most importantly, overexpressed SLC41A1 provide HEK293 cells with an increased magnesium efflux capacity. With outwardly directed Mg(2+) gradients, a SLC41A1-dependent reduction of the free intracellular magnesium concentration accompanied by a significant net decrease of the total cellular magnesium concentration could be observed in such cells. SLC41A1 activity is temperature-sensitive but not sensitive to the only known magnesium channel blocker, cobalt(III) hexaammine. Taken together, these data functionally identify SLC41A1 as a mammalian carrier mediating magnesium efflux.
Kolisek
Martin
M
Institute of Veterinary-Physiology, FU Berlin, Oertzenweg 19b, D-14163 Berlin, Germany. martink@zedat.fu-berlin.de
Launay
Pierre
P
Beck
Andreas
A
Sponder
Gerhard
G
Serafini
Nicolas
N
Brenkus
Marcel
M
Froschauer
Elisabeth Maria
EM
Martens
Holger
H
Fleig
Andrea
A
Schweigel
Monika
M
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D005816:Genetic Complementation Test; D006801:Humans; D017136:Ion Transport / Q000502:physiology; D008274:Magnesium / Q000378:metabolism*; D051379:Mice; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism
D000970:Antineoplastic Agents; D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C476304:SLC41A1 protein, human; C501065:Slc41a2 protein, mouse; C032300:hexaamminecobalt(II); D003035:Cobalt; D008274:Magnesium