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Related Concept Videos

The Inner Mitochondrial Membrane01:28

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The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria.  In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
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Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
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Translocation of Proteins into the Mitochondria01:19

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Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
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Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
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Author Spotlight: Decoding Mitochondrial Aging
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Mapping the evolution of mitochondrial complex I through structural variation.

Dong-Woo Shin1, Tingting Chen1, James A Letts1

  • 1Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.

FEBS Letters
|October 10, 2025
PubMed
Summary
This summary is machine-generated.

Mitochondrial complex I (CI) structure varies across eukaryotes, with accessory subunits differing between lineages. This biodiversity offers insights into metabolic niches and molecular evolution patterns.

Keywords:
OXPHOSbioenergeticscellular respirationcomplex IcryoEM structuresevolutionlast eukaryotic common ancestormetabolismmitochondria

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Area of Science:

  • Biochemistry
  • Molecular Biology
  • Evolutionary Biology

Background:

  • Mitochondrial complex I (CI) is a crucial enzyme in ATP production via oxidative phosphorylation.
  • CI comprises a conserved core of 14 subunits and variable accessory subunits, forming an L-shaped structure.
  • Structural variations exist in both core and accessory subunits across different eukaryotic lineages.

Purpose of the Study:

  • To compare seven representative CI structures from diverse eukaryotic lineages.
  • To identify variable aspects of CI core subunits.
  • To classify eukaryotic accessory subunits based on their conservation from the last eukaryotic common ancestor (LECA) or lineage specificity.

Main Methods:

  • Comparative structural analysis of seven eukaryotic mitochondrial complex I structures.
  • Identification and classification of accessory subunits.
  • Analysis of structural variations in core subunits.

Main Results:

  • Identified conserved and variable regions within the core subunits of mitochondrial complex I.
  • Classified accessory subunits into those conserved from LECA and those specific to certain lineages.
  • Documented structural variations in core subunits across divergent eukaryotic clades.

Conclusions:

  • Eukaryotic mitochondrial complex I exhibits significant biodiversity in its accessory subunits and structural variations in core subunits.
  • Understanding CI evolution and diversity can illuminate metabolic adaptations and inform molecular evolution models.
  • Comparative structural analysis provides a framework for studying mitochondrial respiratory chain evolution.