Related Experiment Video
Updated: Jun 12, 2026
07:24
Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
Published on: February 10, 2023
Undetected antisense tRNAs in mitochondrial genomes?
1Department of Biology, University of Oslo, Center for Ecological and Evolutionary Synthesis, Blindern, 3016 Oslo, Norway. hselig1@yahoo.com
Biology Direct
|June 18, 2010
Summary
Mitochondrial tRNA genes may code for both sense and antisense tRNAs, potentially explaining mutation pathogenicity. Processed antisense tRNAs show adaptations for translational activity, suggesting coevolution.
Area of Science:
- Mitochondrial genetics
- RNA biology
- Molecular evolution
Background:
- Exploring the hypothesis of sense-antisense coding in mitochondrial tRNA genes.
- Investigating the link between mitochondrial tRNA mutations and pathogenicity.
- Examining the role of tRNA punctuation in mitochondrial RNA maturation.
Purpose of the Study:
- To investigate the sense-antisense coding hypothesis in mitochondrial tRNA genes.
- To analyze the properties of antisense tRNAs, including processing, stability, and misacylation.
- To understand the implications for mitochondrial translational activity and mutation effects.
Main Methods:
- Analysis of antisense tRNA 5' and 3' end processing by sense RNA maturation.
- Assessment of tRNA cloverleaf stability.
- Evaluation of tRNA misacylation potential.
- Genome-wide analysis of tRNA properties in relation to cognate amino acid usage.
Main Results:
- Processed antisense tRNAs exhibit better alignment with cognate sequences, indicating reduced misacylation.
- Misacylation rates correlate with cloverleaf fragility and processing inaccuracy.
- Antisense tRNA properties improve with increased genome-wide usage of their cognate amino acid.
Conclusions:
- Antisense tRNAs appear to have coevolved for translational activity or to avoid it.
- Mitochondrial tRNA aminoacylation specificity is influenced by complex competition dynamics.
- Alignment methods for detecting tRNA cognates are robust, even with apparent misacylation potential.
Related Concept Videos
02:59Animal Mitochondrial Genetics
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...
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 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...
01:48ATP 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 ATP...
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...
01:34Protein 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...