Related Experiment Video
Updated: Aug 9, 2025
08:37
Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution
Published on: June 1, 2017
14.2K
Stress-dependent macromolecular crowding in the mitochondrial matrix
Elianne P Bulthuis1, Cindy E J Dieteren1,2, Jesper Bergmans3
1Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands.
The EMBO Journal
|February 24, 2023
Summary
Mitochondrial matrix crowding was investigated using fluorescent peptides. Results show crowding occurs in both healthy and unhealthy mitochondria, impacting biochemical reactions.
Area of Science:
- Cell Biology
- Biophysics
Background:
- Macromolecules induce cellular crowding, affecting biochemical reactions by altering viscosity and volume.
- Mitochondria are protein-rich, but matrix crowding remains poorly understood due to protein immobilization.
Purpose of the Study:
- To determine if the mitochondrial matrix exhibits macromolecular crowding.
- To investigate the impact of mitochondrial dysfunction on matrix crowding.
Main Methods:
- Utilized fluorescent protein fusion peptides (AcGFP1 concatemers) in HeLa cell mitochondria.
- Measured concatemer diffusion and matrix viscosity under normal and chloramphenicol-induced dysfunctional conditions.
Main Results:
- Concatemer diffusion decreased with increasing molecular weight, indicative of crowding.
- Chloramphenicol treatment increased matrix viscosity eightfold and enhanced crowding effects.
- Mitochondrial dysfunction altered matrix crowding without inducing specific stress responses.
Conclusions:
- The mitochondrial matrix exhibits macromolecular crowding in both functional and dysfunctional states.
- Changes in matrix crowding influence biochemical reactions based on reactant and crowder molecular weights.
Related Concept Videos
01:37Energy to Drive Translocation
2.1K
Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
Generally, polypeptides are unfolded by two distinct...
2.1K
01:39Mitochondrial Protein Sorting
4.4K
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.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
4.4K
01:19Translocation of Proteins into the Mitochondria
3.2K
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
3.2K
01:28The Inner Mitochondrial Membrane
3.5K
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...
3.5K
01:41The Supercomplexes in the Crista Membrane
2.6K
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
2.6K
01:39Mitochondrial Precursor Proteins
2.6K
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial...
Most of the mitochondrial...
2.6K