Related Experiment Video

Updated: Jun 9, 2025

Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography
10:39

Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography

Published on: September 14, 2014

29.8K

The mitochondrial citrate synthase from Tetrahymena thermophila does not form an intermediate filament

Stefano Lometto1, Daniela Sparvoli2, Gabriele Malengo3

  • 1Evolutionary Biochemistry Group, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany.

European Journal of Protistology
|October 21, 2024
PubMed

Insights

Mitochondrial citrate synthase (mCS) from Tetrahymena does not form filaments in vivo, contrary to previous reports. Recombinant protein self-assembly is an artifact of specific buffer conditions, not an evolved cytoskeletal function.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Evolutionary Biology

Background:

  • Mitochondrial citrate synthase (mCS) in Tetrahymena thermophila was previously suggested to form filamentous structures during conjugation.
  • This proposed behavior hinted at a recent evolutionary origin of a novel cytoskeletal element.

Purpose of the Study:

  • To re-investigate the in vivo filament-forming ability of Tetrahymena's mCS.
  • To determine the evolutionary emergence and functional significance of mCS filamentation.

Main Methods:

  • Utilized strep-tagged mCS and monoclonal antibodies in Tetrahymena for in vivo analysis.
  • Performed extensive biochemical characterization of recombinant mCS.
  • Analyzed fiber-deficient GFP-tagged mutants.

Main Results:

  • No evidence of filamentous structures of mCS was found in vivo during conjugation or starvation.
  • Biochemical analysis revealed that recombinant mCS self-assembly is an artifact induced by MES and HEPES buffers.
  • Mutant analysis showed no indicative phenotypes, suggesting no structural role in reproduction or metabolism.

Conclusions:

  • Tetrahymena mCS does not form filaments in vivo.
  • The previously reported self-assembly of recombinant mCS is an artifact of specific buffer components.
  • mCS has not evolved a structural role in Tetrahymena's sexual reproduction or metabolic regulation.
Keywords:
Citrate synthaseConjugationIntermediate filamentMES bufferTetrahymena

More Related Videos

Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution08:37

Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution

Published on: June 1, 2017

14.1K
Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae08:55

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae

Published on: July 19, 2021

2.8K

Related Concept Videos

ATP Synthase: Mechanism01:48

ATP Synthase: Mechanism

In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased...
14.0K
Formation of Intermediate Filaments00:57

Formation of Intermediate Filaments

Intermediate filaments are cytoskeletal proteins with higher tensile strength and flexibility than microfilaments and microtubules. Unlike the other two cytoskeletal proteins, intermediate filament formation lacks the enzymatic activity to hydrolyze nucleotides like ATP and GTP to generate energy for polymerization. Therefore, the formation of intermediate filaments is multistep self-assembly. The involvement of any accessory proteins in intermediate filament formation has not yet been...
2.9K
The Inner Mitochondrial Membrane01:28

The Inner Mitochondrial Membrane

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...
3.3K
The Structure of Intermediate Filaments01:19

The Structure of Intermediate Filaments

The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of microfilaments (7 nm) and the microtubules (25 nm).  These filaments are highly stable and can remain intact when exposed to high salt concentrations and detergents. These filaments are responsible for providing stability and mechanical support to the cells. They also help in cell adhesion and maintaining tissue integrity.
Intermediate...
3.9K
Assembly of Cytoskeletal Filaments01:18

Assembly of Cytoskeletal Filaments

Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
18.3K
Electron Transport Chain: Complex I and II01:46

Electron Transport Chain: Complex I and II

The mitochondrial electron transport chain (ETC) is the main energy generation system in the eukaryotic cells. However, mitochondria also produce cytotoxic reactive oxygen species (ROS) due to the large electron flow during oxidative phosphorylation. While Complex I is one of the primary sources of superoxide radicals, ROS production by Complex II is uncommon and may only be observed in cancer cells with mutated complexes.
ROS generation is regulated and maintained at moderate levels necessary...
12.0K