Biology subjects

Zuna, K.

Publications and source records attributed to Zuna, K..

2 recordsLinked to original sources

bioRxiv2023

The 2-oxoglutarate/malate carrier extends the family of mitochondrial carriers capable of FA-activated proton transport.

Metabolic reprogramming in cancer cells has been linked to the mitochondrial dysfunction. Recent studies have suggested the mitochondrial 2-oxoglutarate/malate carrier (OGC) as a potential target for preventing cancer progression. Although OGC is known to be a part of the malate/aspartate shuttle, its exact role in cancer metabolism remains unclear. In this study, we investigated the contribution of recombinant murine OGC to the proton transport by measuring the conductance (Gm) of planar lipid bilayer membranes reconstituted with OGC. Our results show that OGC significantly increases Gm only in the presence of free fatty acids (FAs) and 2,4-dinitrophenol, demonstrating for the first time its involvement in proton transport. We found that (i) the increase in OGC activity directly correlates with the increase in the number of unsaturated bonds of FAs, and (ii) OGC substrates and inhibitors compete with FAs for the same binding site. In addition, we have identified R90 as a crucial amino acid of the binding site for FAs, ATP, 2-oxoglutarate, and malate, which is a first step towards understanding the OGC-mediated proton transport mechanism. Elucidating the contribution of OGC to the uncoupling will be crucial in the design of targeted drugs for the treatment of cancer and other metabolic diseases.

biophysics↗

bioRxiv2022

Membrane lipid reshaping underlies oxidative stress sensing by the mitochondrial proteins UCP1 and ANT1

Oxidative stress and ROS are important players in the pathogenesis of several diseases. Besides the direct modification of proteins, ROS modify lipids with negative spontaneous curvature, such as phosphatidylethanolamine (PE), producing PE adducts and lysolipids. The formation of PE-adducts potentiates the protonophoric activity of the uncoupling protein 1 (UCP1), but the molecular mechanism remains obscure. Here, we connected the ROS-mediated lipid shape alteration with the membrane mechanical properties and function of UCP1 and adenine nucleotide translocase 1 (ANT1). We found that lysophosphatidylcholines (OPC and MPC) and PE adducts decrease a bending modulus in lipid bilayers and increase the protonophoric activity of both proteins. Furthermore, MD simulations revealed that modified PEs and lysolipids alter the membrane lateral pressure profile in the same direction and range, indicating that modified PEs act as lipids with positive spontaneous curvature. Both results indicate that oxidative stress decreases stored curvature elastic stress (SCES) in the lipid bilayer membrane. In conclusion, we demonstrate that UCP1 and ANT1 sense SCES and propose a new regulatory mechanism for the function of these proteins.

biophysics↗