Function of Yeast Bax Inhibitor BXI1 in Redox and Calcium Homeostasis of the Endoplasmic Reticulum and Programmed Cell Death in Saccharomyces cerevisiae

Abstract

Yeast Bax Inhibitor‐1 (BXI1/YBH3) encodes a protein (Bxi1p) that belongs to the Bax Inhibitor family of proteins. In mammals, this family of proteins has cytoprotective properties that are most evident in paradigms of endoplasmic reticulum (ER) stress and have been linked to several human cancers. Both the crystal structure of a prokaryotic member of the family (BsYetJ) and our own published studies suggest that yeast Bxi1p is a pH‐sensitive calcium leak channel localized to the ER membrane. It is involved in the unfolded protein response (UPR). Bxi1p is thought to act via a mechanism involving altered calcium dynamics. We now show that cells lacking BXI1 have an altered redox microenvironment in the ER. We also report that cells lacking BXI1 accumulate more calcium in the ER than wild type cells. Together, our data suggest that Bxi1p is involved in regulating the ER microenvironment and, consequently, programmed cell death.Support or Funding InformationOur laboratory is supported by grant NIGMS R15 GM110578, awarded to N. Austriaco.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.