ABSTRACT

Introduction ................................................................................................................................. 128 Size of plant mitochondrial DNA ............................................................................................. 129 Structural complexity of plant mtDNA ................................................................................... 129 Replication of plant mtDNA ...................................................................................................... 131 Enzymes involved in mtDNA replication ............................................................................... 131

DNA polymerases .................................................................................................................. 131 DNA primase and helicase ................................................................................................... 132 Recombinase ........................................................................................................................... 132 SSB protein .............................................................................................................................. 133 Topoisomerase ........................................................................................................................ 133

Fission, fusion, and segregation of mtDNA ............................................................................ 133 mtDNA recombinations ............................................................................................................. 134 Transcription in plant mitochondria ........................................................................................ 134

Mitochondrial promoters ...................................................................................................... 135 Mitochondrial phage-type RNAPs ...................................................................................... 136 Auxiliary factors required for mtDNA transcription ........................................................ 136

Mitochondrial transcript maturation ....................................................................................... 137 Alteration of the 5′ and 3′ ends ............................................................................................ 137 Polyadenylation ...................................................................................................................... 138 RNA splicing ........................................................................................................................... 138 RNA editing ............................................................................................................................ 139

Regulation of transcription ........................................................................................................ 139 Translation in plant mitochondria ............................................................................................ 140

Ribosomal proteins and ribosomal RNAs .......................................................................... 141 Aminoacyl-tRNA synthetases .............................................................................................. 141 Transfer ribonucleic acids ..................................................................................................... 141 Translation initiation codons ................................................................................................ 141

mRNA surveillance ..................................................................................................................... 142 Hydrophobic nature of mitochondrial proteins ..................................................................... 142 Translational regulation ............................................................................................................. 142 Summary and future perspectives ........................................................................................... 143 References .................................................................................................................................... 144

Abstract

Mitochondria are known to have evolved from free-living a-proteobacteria through endosymbiosis. During evolution, the endosymbiont genes were either lost or transferred to the nuclear genome. The organelle now encodes a limited subset of proteins that are chiey components of the electron transport chain complexes, transcriptional, and translational apparatus. Gene expression in mitochondria comprises distinct transcriptional and posttranscriptional steps. Currently, researchers devote much effort to investigate the regulation of mitochondrial gene expression. Although these investigations do illustrate differences in transcriptional rates and transcript abundances of mitochondrial-encoded genes, it is still unclear whether there is regulation at the level of transcription initiation and/or there is a gene-or genome-specic regulation in mitochondria. Many nuclear genes that encode mitochondrial proteins are regulated at both transcriptional and posttranscriptional level, whereas the regulation of mitochondrial-encoded genes is less clear. Regulation of mitochondrial translation has been investigated extensively in yeast. However, regulation of plant mitochondrial genes at the translational level is much less understood. This chapter presents a summary of the advances made in mitochondrial omics and biotechnology, as well as future prospects.