Unraveling the functions of type II-prohibitins in Arabidopsis mitochondria.

In yeast and mammals, prohibitins (PHBs) are considered as structural proteins that form a scaffold-like structure for interacting with a set of proteins involved in various processes occurring in the mitochondria. The role of PHB in plant mitochondria is poorly understood. In the study, the model organism Arabidopsis thaliana was used to identify the possible roles of type-II PHBs (homologs of yeast Phb2p) in plant mitochondria.

Insights into eukaryotic Rubisco assembly - crystal structures of RbcX chaperones from Arabidopsis thaliana.

Background: Chloroplasts were formed by uptake of cyanobacteria into eukaryotic cells ca. 1.6 billion years ago.

Changes in accumulation of heteroplasmic mitochondrial DNA and frequency of recombination via short repeats during plant lifetime in Phaseolus vulgaris.

Recombination via short repeats in plant mitochondrial genomes results in sublimons--DNA molecules with a copy number much lower compared to the main mitochondrial genome. Coexistence of stoichiometrically different mitotypes, called heteroplasmy, plays an important evolutionary role, since sublimons occasionally replace the main genome resulting in a new plant phenotype. It is not clear, how frequency of recombination and sublimon production is regulated and how it is related to changes in the quantity of the main genome and sublimons.

Initial characteristics of RbcX proteins from Arabidopsis thaliana.

Form I of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is composed of eight large (RbcL) and eight small (RbcS) subunits. Assembly of these subunits into a functional holoenzyme requires the assistance of additional assembly factors. One such factor is RbcX, which has been demonstrated to act as a chaperone in the assembly of most cyanobacterial Rubisco complexes expressed in heterologous system established in Escherichia coli cells.

ATP-dependent proteases in biogenesis and maintenance of plant mitochondria.

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 profiles and proposed functions, with special emphasis on their impact on plant growth and development. The best characterized plant mitochondrial ATP-dependent proteases are AtLon1 and AtFtsH4.

Identification and characterization of high molecular weight complexes formed by matrix AAA proteases and prohibitins in mitochondria of Arabidopsis thaliana.

We identify and characterize two matrix (m)-AAA proteases (AtFtsH3 and AtFtsH10) present in the mitochondria of Arabidopsis thaliana. AtFtsH3 is the predominant protease in leaves of wild type plants. Both proteases assemble with prohibitins (PHBs) into high molecular weight complexes (approximately 2 MDa), similarly to their yeast counterparts.

[Evolution of the mitochondrial DNA and its expression system--comparison between animal and plant kingdom].

The information about features of the Eukaryotic cells is maintained not only in the nucleus, but also in the extranuclear genomes localized in mitochondria and chloroplasts. Comparison between plant and animal mitochondrial genomes allows to perceive two extremely distinct evolution strategies. Animals clearly tend to reduce the size of the mitochondrial genome to the minimum.

G8363A mitochondrial DNA mutation is not a rare cause of Leigh syndrome - clinical, biochemical and pathological study of an affected child.

Unlabelled: Leigh syndrome (LS), or subacute necrotizing encephalomyelopathy, having relatively homogeneous clinical symptomatology and pattern of neuropathological changes, shows remarkable heterogeneity in biochemical and molecular background. G8363A mitochondrial DNA mutation typical for MERRF syndrome and progressive cardiomyopathy may also be associated with LS. Clinical, biochemical and pathological findings in a boy aged 28 months who died with classical COX-deficientLSassociatedwithmtG8363Aisdescribedindetail.

Nuclear and mitochondrial genome responses in HeLa cells treated with inhibitors of mitochondrial DNA expression.

The influence of mutations in the mitochondrial DNA (mtDNA) on the bioenergetic metabolism of the cell is still poorly understood. Many of the mutations in the mtDNA affect the expression of the mitochondrial genome. Investigations on cells from patients are not easy, especially as the mitochondrial DNA is heteroplasmic and this state is changed in culture.

Differential stability of mitochondrial mRNA in HeLa cells.

The physiological significance and metabolism of oligoadenylated and polyadenylated human mitochondrial mRNAs are not known to date. After study of eight mitochondrial transcripts (ND1, ND2, ND3, ND5, CO1, CO2, ATP6/8 and Cyt. b) we found a direct correlation between the half-lives of mitochondrial mRNAs and their steady-state levels.

Comparison between the Polish population and European populations on the basis of mitochondrial morphs and haplogroups.

Polymorphisms in mitochondrial DNA (mtDNA) were analyzed in 152 samples from the Polish population using restriction enzymes AvaI, BamHI, HaeII, HpaI and PstI. Additionally, each sample was classified into the appropriate haplogroup. When required, appropriate fragments were sequenced to establish the exact polymorphic sites.

Leber hereditary optic neuropathy--a disease with a known molecular basis but a mysterious mechanism of pathology.

Leber hereditary optic neuropathy is a maternally inherited type of blindness caused by degeneration of the optic nerve. It is caused by point mutations in mitochondrial DNA. Like in other mitochondrial diseases, its penetrance and inheritance is complicated by heteroplasmy, tissue distribution, and the bottleneck phenomenon in oocyte maturation.