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MSL 1 is a mechanosensitive ion channel that dissipates mitochondrial membrane potential and maintains redox homeostasis in mitochondria during abiotic stress
Author(s) -
Lee Chun Pong,
Maksaev Grigory,
Jensen Gregory S.,
Murcha Monika W.,
Wilson Margaret E.,
Fricker Mark,
Hell Ruediger,
Haswell Elizabeth S.,
Millar A. Harvey,
Sweetlove Lee J.
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13301
Subject(s) - mechanosensitive channels , membrane potential , mitochondrion , redox , ion channel , chemistry , biophysics , microbiology and biotechnology , homeostasis , biology , biochemistry , inorganic chemistry , receptor
Summary Mitochondria must maintain tight control over the electrochemical gradient across their inner membrane to allow ATP synthesis while maintaining a redox‐balanced electron transport chain and avoiding excessive reactive oxygen species production. However, there is a scarcity of knowledge about the ion transporters in the inner mitochondrial membrane that contribute to control of membrane potential. We show that loss of MSL 1, a member of a family of mechanosensitive ion channels related to the bacterial channel MscS, leads to increased membrane potential of Arabidopsis mitochondria under specific bioenergetic states. We demonstrate that MSL 1 localises to the inner mitochondrial membrane. When expressed in Escherichia coli , MSL 1 forms a stretch‐activated ion channel with a slight preference for anions and provides protection against hypo‐osmotic shock. In contrast, loss of MSL 1 in Arabidopsis did not prevent swelling of isolated mitochondria in hypo‐osmotic conditions. Instead, our data suggest that ion transport by MSL 1 leads to dissipation of mitochondrial membrane potential when it becomes too high. The importance of MSL 1 function was demonstrated by the observation of a higher oxidation state of the mitochondrial glutathione pool in msl1‐1 mutants under moderate heat‐ and heavy‐metal‐stress. Furthermore, we show that MSL 1 function is not directly implicated in mitochondrial membrane potential pulsing, but is complementary and appears to be important under similar conditions.

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