Adaptation of Mge1 to oxidative stress by local unfolding and altered Interaction with mitochondrial Hsp70 and Mxr2.

Perturbations in mitochondrial redox levels oxidize nucleotide exchanger Mge1, compromising its ability to bind to the Hsp70, while the Mxr2 enzyme reduces the oxidized Mge1. However, the effects of persistent oxidative stress on Mge1 structure and function are not known. In this study, we show that oxidation-induced selective and local structural adaptations cause the detachment of Mge1 from Hsp70. Notably, persistent oxidative stress causes monomeric Mge1 to aggregate and to generate amyloid-type particles. Mxr2 appears to protect Mge1 from oxidative stress induced aggregation. We conclude that the Mxr2-Mge1-Hsp70 protein triad is finely regulated through structural alterations of Mge1 mediated by redox levels.