TY - JOUR

T1 - Endoplasmic reticulum transport of glutathione by Sec61 is regulated by Ero1 and Bip

AU - Ponsero, Alise J.

AU - Igbaria, Aeid

AU - Darch, Maxwell A.

AU - Miled, Samia

AU - Outten, Caryn E.

AU - Winther, Jakob R.

AU - Palais, Gael

AU - D'Autréaux, Benoit

AU - Delaunay-Moisan, Agnès

AU - Toledano, Michel B.

PY - 2017/9/21

Y1 - 2017/9/21

N2 - In the endoplasmic reticulum (ER), Ero1 catalyzes disulfide bond formation and promotes glutathione (GSH) oxidation to GSSG. Since GSSG cannot be reduced in the ER, maintenance of the ER glutathione redox state and levels likely depends on ER glutathione import and GSSG export. We used quantitative GSH and GSSG biosensors to monitor glutathione import into the ER of yeast cells. We found that glutathione enters the ER by facilitated diffusion through the Sec61 protein-conducting channel, while oxidized Bip (Kar2) inhibits transport. Increased ER glutathione import triggers H2O2-dependent Bip oxidation through Ero1 reductive activation, which inhibits glutathione import in a negative regulatory loop. During ER stress, transport is activated by UPR-dependent Ero1 induction, and cytosolic glutathione levels increase. Thus, the ER redox poise is tuned by reciprocal control of glutathione import and Ero1 activation. The ER protein-conducting channel is permeable to small molecules, provided the driving force of a concentration gradient. Ponsero et al. show that cytosol-to-ER transport of glutathione proceeds via facilitated diffusion through Sec61. Upon import, glutathione activates Ero1 by reduction, causing Bip oxidation and inhibition of glutathione transport. Coupling of glutathione ER import to Ero1 activation provides a basis for glutathione ER redox poise maintenance.

AB - In the endoplasmic reticulum (ER), Ero1 catalyzes disulfide bond formation and promotes glutathione (GSH) oxidation to GSSG. Since GSSG cannot be reduced in the ER, maintenance of the ER glutathione redox state and levels likely depends on ER glutathione import and GSSG export. We used quantitative GSH and GSSG biosensors to monitor glutathione import into the ER of yeast cells. We found that glutathione enters the ER by facilitated diffusion through the Sec61 protein-conducting channel, while oxidized Bip (Kar2) inhibits transport. Increased ER glutathione import triggers H2O2-dependent Bip oxidation through Ero1 reductive activation, which inhibits glutathione import in a negative regulatory loop. During ER stress, transport is activated by UPR-dependent Ero1 induction, and cytosolic glutathione levels increase. Thus, the ER redox poise is tuned by reciprocal control of glutathione import and Ero1 activation. The ER protein-conducting channel is permeable to small molecules, provided the driving force of a concentration gradient. Ponsero et al. show that cytosol-to-ER transport of glutathione proceeds via facilitated diffusion through Sec61. Upon import, glutathione activates Ero1 by reduction, causing Bip oxidation and inhibition of glutathione transport. Coupling of glutathione ER import to Ero1 activation provides a basis for glutathione ER redox poise maintenance.

KW - Bip

KW - disulfide bond

KW - endoplasmic reticulum

KW - Ero1

KW - glutathione

KW - membrane transport

KW - oxidative protein folding

KW - redox biosensor

KW - redox homeostasis

KW - Sec61

UR - http://www.scopus.com/inward/record.url?scp=85029425842&partnerID=8YFLogxK

U2 - 10.1016/j.molcel.2017.08.012

DO - 10.1016/j.molcel.2017.08.012

M3 - Journal article

C2 - 28918898

AN - SCOPUS:85029425842

VL - 67

SP - 962-973.e5

JO - Molecular Cell

JF - Molecular Cell

SN - 1097-2765

IS - 6

ER -