Malgorzata Kwasniak-Owczarek

University of Wroclaw | WROC · Faculty of Biotechnology

Plant mitochondria and chloroplasts are semi-autonomous organelles originated from free-living bacteria that have retained reduced genomes during evolution. As a consequence, relatively few of the mitochondrial and chloroplast proteins are encoded in the organellar genomes and synthesized by the organellar ribosomes. Since both organellar genomes e...

Mitochondria are subcellular organelles with their own genome and expression system, including translation machinery to make proteins. Several independent studies have shown that translation is an essential regulatory step in expression of the plant mitochondrial genome. Thus, the study of mitochondrial translation seems to be crucial for the compr...

Changes in the functional state of mitochondria have profound effects on other cellular compartments. Genome-wide expression analysis of Arabidopsis rps10 mutants with an RNAi-silenced expression of mitoribosomal S10 protein has revealed extensive transcriptional reprogramming. A meta-analysis comparing expression datasets of 25 mitochondrial pertu...

Contrary to the widely held belief that mitochondrial ribosomes (mitoribosomes) are highly similar to bacterial ones, recent experimental evidence reveals that mitoribosomes do differ significantly from their bacterial counterparts. This review is focused on plant mitoribosomes, but we also highlight the most striking similarities and differences b...

The ribosome is not only a protein-making machine, but also a regulatory element in protein synthesis. This view is supported by our earlier data showing that Arabidopsis mitoribosomes altered due to the silencing of the nuclear RPS10 gene encoding mitochondrial ribosomal protein S10 differentially translate mitochondrial transcripts compared with...

The ribosome profiling approach (Ribo-seq) is currently the most effective method to study the protein synthesis in vivo. This technique relies on sequencing of ribosome protected mRNA fragments (so-called ribosomal footprints) allowing to indicate the exact positions of ribosomes on transcripts. Advanced bioinformatic analysis of Ribo-seq data ena...

Seed germination provides an excellent model to study the process of mitochondrial biogenesis. It is a complex and strictly regulated process which requires a proper biogenesis of fully active organelles from existing promitochondrial structures. We have previously reported that the lack of the inner mitochondrial membrane protease FTSH4 delayed Ar...

FTSH4 is one of the inner membrane-embedded ATP-dependent metalloproteases in mitochondria of Arabidopsis thaliana. In mutants impaired to express FTSH4 carbonylated proteins accumulated and leaf morphology was altered when grown under short-day photoperiod, at 22{degree sign}C, and long-day photoperiod, at 30{degree sign}C. To provide better insig...

The ribosome filter hypothesis posits that ribosomes are not simple non-selective translation machines but may also function as regulatory elements in protein synthesis. Recent data supporting ribosomal filtering come from plant mitochondria where it has been shown that translation of mitochondrial transcripts encoding components of oxidative phosp...

Hardly anything is known about translational control of plant mitochondrial gene expression. Here, we provide evidence for differential translation of mitochondrial transcripts in Arabidopsis thaliana. We found that silencing of the nuclear RPS10 gene encoding mitochondrial ribosomal protein S10 disturbs the ratio between the small and large subuni...

This review focuses on organellar AAA/FtsH proteases, whose proteolytic and chaperone-like activity is a crucial component of the protein quality control systems of mitochondrial and chloroplast membranes. We compare the AAA/FtsH proteases from yeast, mammals and plants. The nature of the complexes formed by AAA/FtsH proteases and the current view...

The existence of a proteolytic system which can specifically recognize and cleave proteins in mitochondria is now well established. The components of this system comprise processing peptidases, ATP-dependent peptidases and oligopeptidases. A short overview of experimentally confirmed proteases mainly from Arabidopsis thaliana is provided. The role...

ATP-dependent proteases from three families have been identified experimentally in Arabidopsis mitochondria: four FtsH proteases (AtFtsH3, AtFtsH4, AtFtsH10, and AtFtsH11), two Lon proteases (AtLon1 and AtLon4), and one Clp protease (AtClpP2 with regulatory subunit AtClpX). In this review we discuss their submitochondrial localization, expression p...