Related Experiment Video
Updated: May 23, 2026
14:44
Isolation of mRNAs Associated with Yeast Mitochondria to Study Mechanisms of Localized Translation
Published on: March 14, 2014
Mitochondrial nucleoid interacting proteins support mitochondrial protein synthesis
1MRC-Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road Cambridge, CB2 0XY, UK.
Nucleic Acids Research
|March 29, 2012
Summary
Mitochondrial ribosomes associate with DNA in human cells, revealing a link between protein synthesis and mitochondrial DNA maintenance. Key proteins ATAD3 and prohibitin are crucial for this process.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Molecular Genetics
Background:
- Mitochondrial nucleoids are complexes of DNA and proteins.
- The precise composition and function of nucleoid proteins are not fully understood.
- Mitochondrial protein synthesis is essential for cellular respiration.
Purpose of the Study:
- To identify proteins that associate with mitochondrial nucleoids in human cells.
- To investigate the role of identified proteins in mitochondrial DNA (mtDNA) maintenance and protein synthesis.
Main Methods:
- Affinity purification of tagged mitochondrial DNA binding proteins.
- Co-purification of associated proteins, including ribosomal components.
- Analysis of protein expression levels and their impact on mtDNA and protein synthesis.
Main Results:
- Mitochondrial ribosomes and translation factors were found to co-purify with mitochondrial nucleoids.
- ATAD3 (ATPase family, AAA domain containing 3) and prohibitin were identified as major nucleoid components.
- ATAD3 and prohibitin are essential for mitochondrial protein synthesis.
- Altered ATAD3 expression affects mtDNA maintenance and replication.
Conclusions:
- There is an intimate association between mitochondrial nucleoids and the protein synthesis machinery.
- ATAD3 and prohibitin, located at the inner mitochondrial membrane, likely support nucleic acid complexes.
- These findings highlight a functional link between mtDNA organization and mitochondrial gene expression.
Related Concept Videos
01:39Mitochondrial Protein Sorting
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...
01:19Translocation of Proteins into the Mitochondria
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,...
01:39Mitochondrial Precursor Proteins
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 precursors...
Most of the mitochondrial precursors...
01:12Porin Insertion in the Outer Mitochondrial Membrane
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.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
02:53Ribosomal RNA Synthesis
Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...