Relationship between mitochondrial gene rearrangements and stability of the origin of light strand replication

Miguel M Fonseca,D James Harris

doi:10.1590/s1415-47572008000300027

Miguel M Fonseca, D James Harris

Open Access

https://doi.org/10.1590/s1415-47572008000300027

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Journal: Genetics and Molecular Biology	Publication Date: Jan 1, 2008
Citations: 45	License type: cc-by

Affiliation: University of Porto

Abstract

Mitochondrial gene rearrangements are much more frequent in vertebrates than initially thought. It has been suggested that the origin of light strand replication could have an important role in the process of gene rearrangements, but this hypothesis has never been tested before. We used amphibians to test the correlation between light-strand replication origin thermodynamic stability and the occurrence of gene rearrangements. The two variables were correlated in a non-phylogenetic approach, but when tested in a phylogenetically based comparative method the correlation was not significant, although species with unstable light-strand replication origins were much more likely to have undergone gene rearrangements. This indicates that within amphibians there are stable and unstable phylogenetic groups regarding mitochondrial gene order. The species analyzed showed variability in the thermodynamic stability of the secondary structure, in the length of its stem and loop, and several species did not present the 5’-GCCGG-3’ motif reported to be necessary for efficient mitochondrial DNA replication. Future studies should focus on the role of the light-strand replication origin in mitochondrial DNA replication and gene rearrangements mechanisms.

Highlights

Mitochondrial gene order was thought to be highly conserved within vertebrates based on the gene order of the first genomes sequenced (Anderson et al, 1981, 1982; Bibb et al, 1981; Roe et al, 1985)
In the study described in this paper we examined the thermodynamic stability of the OL region and investigated the possible association of such stability with the incidence of gene rearrangements, including partial genome duplications (PGD)
The length of the vertebrate mitochondrial DNA (mtDNA) molecule is not conserved and its variation is typically associated with duplications in the control region, varying from less than 100 bp up to 8.0 kbp (Moritz, 1991), which means that species with or without partial genome duplications cannot be clearly separated

Summary

Introduction

Mitochondrial (mt) gene order was thought to be highly conserved within vertebrates based on the gene order of the first genomes sequenced (Anderson et al, 1981, 1982; Bibb et al, 1981; Roe et al, 1985). With the increasing number of whole mitochondrial genomes published it is clear that gene order stability within vertebrates is group specific - mammals and birds have relatively stable gene orders, while in amphibians, reptiles and fish rearrangements are more common (Pereira, 2000).

Results

Conclusion