TY - JOUR
T1 - Selective electrodiffusion of zinc ions in a Zrt-, Irt-like protein, ZIPB
AU - Lin, Wei
AU - Chai, Jin
AU - Love, James
AU - Fu, Dax
PY - 2010/12/10
Y1 - 2010/12/10
N2 - All living cells need zinc ions to support cell growth. Zrt-, Irt-like proteins (ZIPs) represent a major route for entry of zinc ions into cells, but how ZIPs promote zinc uptake has been unclear. Here we report the molecular characterization of ZIPB from Bordetella bronchiseptica, the first ZIP homolog to be purified and functionally reconstituted into proteoliposomes. Zinc flux through ZIPB was found to be nonsaturable and electrogenic, yielding membrane potentials as predicted by the Nernst equation. Conversely, membrane potentials drove zinc fluxes with a linear voltage-flux relationship. Direct measurements of metal uptake by inductively coupled plasma mass spectroscopy demonstrated that ZIPB is selective for two group 12 transition metal ions, Zn2+ and Cd2+, whereas rejecting transition metal ions in groups 7 through 11. Our results provide the molecular basis for cellular zinc acquisition by a zinc-selective channel that exploits in vivo zinc concentration gradients to move zinc ions into the cytoplasm.
AB - All living cells need zinc ions to support cell growth. Zrt-, Irt-like proteins (ZIPs) represent a major route for entry of zinc ions into cells, but how ZIPs promote zinc uptake has been unclear. Here we report the molecular characterization of ZIPB from Bordetella bronchiseptica, the first ZIP homolog to be purified and functionally reconstituted into proteoliposomes. Zinc flux through ZIPB was found to be nonsaturable and electrogenic, yielding membrane potentials as predicted by the Nernst equation. Conversely, membrane potentials drove zinc fluxes with a linear voltage-flux relationship. Direct measurements of metal uptake by inductively coupled plasma mass spectroscopy demonstrated that ZIPB is selective for two group 12 transition metal ions, Zn2+ and Cd2+, whereas rejecting transition metal ions in groups 7 through 11. Our results provide the molecular basis for cellular zinc acquisition by a zinc-selective channel that exploits in vivo zinc concentration gradients to move zinc ions into the cytoplasm.
UR - http://www.scopus.com/inward/record.url?scp=78649863705&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78649863705&partnerID=8YFLogxK
U2 - 10.1074/jbc.M110.180620
DO - 10.1074/jbc.M110.180620
M3 - Article
C2 - 20876577
AN - SCOPUS:78649863705
SN - 0021-9258
VL - 285
SP - 39013
EP - 39020
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 50
ER -