The radish Ogura fertility restorer impedes translation elongation along its cognate CMS-causing mRNA.

The control of messenger RNA (mRNA) translation has been increasingly recognized as a key regulatory step for gene control, but clear examples in eukaryotes are still scarce. Nucleo-cytoplasmic male sterilities (CMS) represent ideal genetic models to dissect genetic interactions between the mitochondria and the nucleus in plants. This trait is determined by specific mitochondrial genes and is associated with a pollen sterility phenotype that can be suppressed by nuclear genes known as restorer-of-fertility ().

A Case of Gene Fragmentation in Plant Mitochondria Fixed by the Selection of a Compensatory Restorer of Fertility-Like PPR Gene.

The high mutational load of mitochondrial genomes combined with their uniparental inheritance and high polyploidy favors the maintenance of deleterious mutations within populations. How cells compose and adapt to the accumulation of disadvantageous mitochondrial alleles remains unclear. Most harmful changes are likely corrected by purifying selection, however, the intimate collaboration between mitochondria- and nuclear-encoded gene products offers theoretical potential for compensatory adaptive changes.

The MTL1 Pentatricopeptide Repeat Protein Is Required for Both Translation and Splicing of the Mitochondrial NADH DEHYDROGENASE SUBUNIT7 mRNA in Arabidopsis.

Mitochondrial translation involves a complex interplay of ancient bacteria-like features and host-derived functionalities. Although the basic components of the mitochondrial translation apparatus have been recognized, very few protein factors aiding in recruiting ribosomes on mitochondria-encoded messenger RNA (mRNAs) have been identified in higher plants. In this study, we describe the identification of the Arabidopsis (Arabidopsis thaliana) MITOCHONDRIAL TRANSLATION FACTOR1 (MTL1) protein, a new member of the Pentatricopeptide Repeat family, and show that it is essential for the translation of the mitochondrial NADH dehydrogenase subunit7 (nad7) mRNA.

In vivo functional analysis of a nuclear restorer PPR protein.

Background: Nuclear restorers of cytoplasmic male fertility (CMS) act to suppress the male sterile phenotype by down-regulating the expression of novel CMS-specifying mitochondrial genes. One such restorer gene is Rfo, which restores fertility to the radish Ogura or ogu CMS. Rfo, like most characterized restorers, encodes a pentatricopeptide repeat (PPR) protein, a family of eukaryotic proteins characterized by tandem repeats of a 35 amino acid motif.

Disruption of the CYTOCHROME C OXIDASE DEFICIENT1 gene leads to cytochrome c oxidase depletion and reorchestrated respiratory metabolism in Arabidopsis.

Cytochrome c oxidase is the last respiratory complex of the electron transfer chain in mitochondria and is responsible for transferring electrons to oxygen, the final acceptor, in the classical respiratory pathway. The essentiality of this step makes it that depletion in complex IV leads to lethality, thereby impeding studies on complex IV assembly and respiration plasticity in plants. Here, we characterized Arabidopsis (Arabidopsis thaliana) embryo-lethal mutant lines impaired in the expression of the CYTOCHROME C OXIDASE DEFICIENT1 (COD1) gene, which encodes a mitochondria-localized PentatricoPeptide Repeat protein.

A restorer-of-fertility like pentatricopeptide repeat gene directs ribonucleolytic processing within the coding sequence of rps3-rpl16 and orf240a mitochondrial transcripts in Arabidopsis thaliana.

The pentatricopeptide repeat (PPR) proteins represent a large family of RNA-binding proteins that have many roles in post-transcriptional RNA processes within plant organelles. Among the PPR proteins that target plant mitochondria, the restorer-of-fertility (Rf) proteins are characterized by their inhibitory action on mitochondrion-localized cytoplasmic male sterility (CMS) genes in various crop species. Close homologs to known Rfs from radish, petunia, and rice can be identified in most higher plant species and these proteins define the recognized subgroup of Rf-like (RFL) PPR proteins.

The pentatricopeptide repeat MTSF1 protein stabilizes the nad4 mRNA in Arabidopsis mitochondria.

Gene expression in plant mitochondria involves a complex collaboration of transcription initiation and termination, as well as subsequent mRNA processing to produce mature mRNAs. In this study, we describe the function of the Arabidopsis mitochondrial stability factor 1 (MTSF1) gene and show that it encodes a pentatricopeptide repeat protein essential for the 3'-processing of mitochondrial nad4 mRNA and its stability. The nad4 mRNA is highly destabilized in Arabidopsis mtsf1 mutant plants, which consequently accumulates low amounts of a truncated form of respiratory complex I.

PPR336 is associated with polysomes in plant mitochondria.

The function of pentatricopeptide repeat (PPR) proteins has been associated with various post-transcriptional steps of organelle gene expression. Among them, translation and its regulation are essential processes. However, in plant mitochondria, they are also the steps of gene expression that are the least understood.

The Arabidopsis Bio2 protein requires mitochondrial targeting for activity.

Mitochondria are involved in the production of various vitamins, such as biotin, in plants. It is unclear why these biosynthetic pathways have been maintained partly or entirely within the mitochondria throughout evolution. The last step in biotin biosynthesis occurs within the mitochondria and is catalyzed by the biotin synthase complex containing the BIO2 gene product.