Membrane protein import in yeast mitochondria

Tokatlidis, Kostas; Vial, Sarah; Luciano, Pierre; Vergnolle, M.; Clémence, S.

doi:10.1042/bst0280495

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…The TOM complex in the outer membrane is the entry gate for mitochondrial proteins (Endo and Kohda, 2002). The inner membrane contains the TIM23 and TIM22 complexes which facilitate the import of proteins into the matrix space and into the inner membrane (Tokatlidis et al ., 2000; Jensen and Dunn, 2002; Pfanner and Chacinska, 2002). The OXA1 complex mediates insertion of proteins into the inner membrane from the matrix side (Hell et al ., 2001).…”

Section: Introductionmentioning

confidence: 99%

Tim50, a novel component of the TIM23 preprotein translocase of mitochondria

et al. 2003

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The preprotein translocase of the inner membrane of mitochondria (TIM23 complex) is the main entry gate for proteins of the matrix and the inner membrane. We isolated the TIM23 complex of Neurospora crassa. Besides Tim23 and Tim17, it contained a novel component, referred to as Tim50. Tim50 spans the inner membrane with a single transmembrane segment and exposes a large hydrophilic domain in the intermembrane space. Tim50 is essential for viability of yeast. Mitochondria from cells depleted of Tim50 displayed strongly reduced import kinetics of preproteins using the TIM23 complex. Tim50 could be crosslinked to preproteins that were halted at the level of the translocase of the outer membrane (TOM complex) or spanning both TOM and TIM23 complexes. We suggest that Tim50 plays a crucial role in the transfer of preproteins from the TOM complex to the TIM23 complex through the intermembrane space.

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Section: Introductionmentioning

confidence: 99%

Tim50, a novel component of the TIM23 preprotein translocase of mitochondria

et al. 2003

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“…Thus the electrochemical membrane potential and the chemical potential of ATP hydrolysis are driving unidirectional protein translocation from the cytosol into the matrix. Similarly, inner membrane proteins are imported through the TOM complex and integrated into the inner membrane in a reaction dependent on the membrane potential and, mostly, ATP (for details see Koehler, 2000; Tokatlidis et al ., 2000).…”

Section: Introductionmentioning

confidence: 99%

Import of small Tim proteins into the mitochondrial intermembrane space

2003

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Proteins of the intermembrane space (IMS) of mitochondria are typically synthesized without presequences. Little is known about their topogenesis. We used Tim13, a member of the 'small Tim protein' family, as model protein to investigate the mechanism of translocation into the IMS. Tim13 contains four conserved cysteine residues that bind a zinc ion as cofactor. Import of Tim13 did not depend on the membrane potential or ATP hydrolysis. Upon import into mitochondria Tim13 adopted a stably folded conformation in the IMS. Mutagenesis of the cysteine residues or pretreatment with metal chelators interfered with folding of Tim13 in vitro and impaired its import into mitochondria. Upon depletion of metal ions or modification of cysteine residues, imported Tim13 diffused back out of the IMS. We propose an import pathway in which (1) Tim13 can pass through the TOM complex into and out of the IMS in an unfolded conformation, and (2) cofactor acquisition stabilizes folding on the trans side of the outer membrane and traps Tim13 in the IMS, and drives unidirectional movement of the protein across the outer membrane of mitochondria.

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“…NRF is a transcription factor that stimulates nuclear genes such as CytC, a critical factor in the proper functioning of mitochondria . TOM20, a protein complex located at the outer membrane of mitochondria, allows movement of proteins into the intermembrane of the mitochondria . Increased expression of TOM20 is a way to determine the number of mitochondria.…”

Section: Discussionmentioning

confidence: 99%

“…41 TOM20, a protein complex located at the outer membrane of mitochondria, 42 allows movement of proteins into the intermembrane of the mitochondria. 43 Increased expression of TOM20 is a way to determine the number of mitochondria. Mitochondrial content is also expressed as a copy number, which is maintained in a relatively safe range to meet the energy needs of cells to preserve normal physiological function.…”

Section: ■ Discussionmentioning

confidence: 99%

Fruit of Hovenia dulcis Thunb. Induces Nonshivering Thermogenesis through Mitochondrial Biogenesis and Activation by SIRT1 in High-Fat Diet-Fed Obese Mice and Primary Cultured Brown Adipocytes

Song

Kim

Jung

et al. 2020

J. Agric. Food Chem.

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Brown adipocytes, which contain abundant mitochondria, use stored energy as fuel during a process named nonshivering thermogenesis. Thus, the pharmacological activation of thermogenesis in brown adipose tissue (BAT) has become a promising target for treating obesity. We investigated the effect of fruit of Hovenial dulcis Thunb. (FHD), a frequently used herbal treatment for liver diseases, on thermogenesis and its mechanism using primary cultured brown adipocytes and BAT of high-fat-diet (HFD)-induced obese mice. Thermogenesis-related factors including UCP1 and PGC1α increased with FHD treatment. FHD also increased mitochondrial biogenesis and activation factors such as nuclear respiratory factor (NRF)1 and oxidative phosphorylation (OXPHOS) complex. Furthermore, FHD increased the intercellular nicotinamide adenine dinucleotide (NAD + ) level and sirtuin 1 (SIRT1) activity, which may be responsible for the activation of the thermogenic reaction. Overall, our results suggest that FHD can be a novel option for obesity treatment due to its thermogenic action through mitochondrial biogenesis and activation.

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Membrane protein import in yeast mitochondria

Cited by 9 publications

References 16 publications

Tim50, a novel component of the TIM23 preprotein translocase of mitochondria

Tim50, a novel component of the TIM23 preprotein translocase of mitochondria

Import of small Tim proteins into the mitochondrial intermembrane space

Fruit of Hovenia dulcis Thunb. Induces Nonshivering Thermogenesis through Mitochondrial Biogenesis and Activation by SIRT1 in High-Fat Diet-Fed Obese Mice and Primary Cultured Brown Adipocytes

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