VOLUME 17 (Supplement)

SciEnggJ%202024%20Special%20Issue%201 7 Pasham%20et%20al

SciEnggJ 17 (Supplement) 036-041
available online: February 28, 2024
DOI: https://doi.org/10.54645/202417SupUEV-94

*Corresponding author
Email Address: naustriaco@ust.edu.ph
Date received: December 14, 2023
Date revised: January 21, 2024
Date accepted: January 25, 2024


Overexpressed yeast Bax inhibitor (Bxi1p/Ybh3p) is a calcium channel in E. coli

James Mullin1, John Kalhorn1, Julia Aguiar1, Madelyn Crago1, Nicholas Mello1, Amanda Raffa1, Alexander Strakosha1, and Nicanor Austriaco, O.P.*1,2,3,4

1Department of Biology, Providence College, Providence RI 02918 USA
2Department of Biological Sciences, University of Santo Tomas, Manila
3UST Laboratories for Vaccines Science, Molecular Biology, and
     Biotechnology, University of Santo Tomas, Manila 1015 PHILIPPINES
4Research Center for the Natural and Applied Sciences, University of Santo
     Tomas, Manila 1015 PHILIPPINES

KEYWORDS: Bax Inhibitor, Bxi1p, Ybh3p, calcium channel, TMBIM6, BI-1

Human Bax Inhibitor-1 (HsBI-1/TMBIM6) is the founding member of the evolutionary conserved TMBIM superfamily of proteins that share sequence homology within the transmembrane Bax inhibitor-containing motif (TMBIM). Mechanistically, BI-1/TMBIM6 and all the other mammalian TMBIM proteins appear to be involved in the maintenance of calcium homeostasis, and the crystal structure of a bacterial TMBIM protein, BsYetJ, suggests that the protein is a pH-sensitive calcium leak. The budding yeast, Saccharomyces cerevisiae, has a single TMBIM family member (YNL305C) named Bxi1p/Ybh3p. To determine the function Bxi1p/Ybh3p, we overexpressed Bxi1p-GFP in E. coli to interrogate its putative calcium channel function. We show that bacterial cells expressing Bxi1p-GFP are more permeable to calcium than controls. Our data suggests that yeast Bax inhibitor (Bxi1p) is a calcium channel in E. coli, lending support to our proposal that Bxi1p is a bona fide member of the TMBIM family of proteins. Finally, parallel experiments also revealed that the human Bax Inhibitor-1 (HsBI1/TMBIM6) is also a calcium channel in bacteria.

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