title: MSL1 is a mechanosensitive ion channel that dissipates mitochondrial membrane potential and maintains redox homeostasis in mitochondria during abiotic stress.
abstract: 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 MSL1, 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 MSL1 localises to the inner mitochondrial membrane. When expressed in Escherichia coli, MSL1 forms a stretch-activated ion channel with a slight preference for anions and provides protection against hypo-osmotic shock. In contrast, loss of MSL1 in Arabidopsis did not prevent swelling of isolated mitochondria in hypo-osmotic conditions. Instead, our data suggest that ion transport by MSL1 leads to dissipation of mitochondrial membrane potential when it becomes too high. The importance of MSL1 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 MSL1 function is not directly implicated in mitochondrial membrane potential pulsing, but is complementary and appears to be important under similar conditions.
authors: ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia.
authors: Chun Pong
authors: CP
authors: Lee
authors: Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA.
authors: Grigory
authors: G
authors: Maksaev
authors: Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA.
authors: Gregory S
authors: GS
authors: Jensen
authors: ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia.
authors: Monika W
authors: MW
authors: Murcha
authors: Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA.
authors: Margaret E
authors: ME
authors: Wilson
authors: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
authors: Mark
authors: M
authors: Fricker
authors: Department of Plant Molecular Biology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 360, D-69120, Heidelberg, Germany.
authors: Ruediger
authors: R
authors: Hell
authors: Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA.
authors: Elizabeth S
authors: ES
authors: Haswell
authors: ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia.
authors: A Harvey
authors: AH
authors: Millar
authors: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
authors: Lee J
authors: LJ
authors: Sweetlove
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000235:genetics / Q000502:physiology*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins
keywords: Arabidopsis; mechanosensitive ion channel; membrane potential; mitochondria; oxidative stress; pulsing