The emerging picture of the mitochondrial protein import complexes of Amoebozoa supergroup

Wojtkowska, Małgorzata; Buczek, Dorota; Suzuki, Yutaka; Shabardina, Victoria; Makałowski, Wojciech; Kmita, Hanna

doi:10.1186/s12864-017-4383-1

Cited by 8 publications

(7 citation statements)

References 52 publications

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“…A possible reason could be that CCA1 and CCA2 fulfill different tasks in the cellular compartments since cytoplasmic as well as mitochondrial tRNAs do not encode the CCA end [ 62 ]. Computational predictions of mitochondrial target sequences is not meaningful in this case, as the Dictyostelium mt import system is not well understood [ 63 ]. Furthermore, as the GFP fusions of CCA1 and CCA2 are both evenly distributed in the respective cell compartments, a different substrate specificity in terms of cytoplasmic and mitochondrial tRNAs is unlikely ( Figure 2 ).…”

Section: Discussionmentioning

confidence: 99%

Unusual Occurrence of Two Bona-Fide CCA-Adding Enzymes in Dictyostelium discoideum

Erber

Hoffmann

Fallmann

et al. 2020

IJMS

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Dictyostelium discoideum, the model organism for the evolutionary supergroup of Amoebozoa, is a social amoeba that, upon starvation, undergoes transition from a unicellular to a multicellular organism. In its genome, we identified two genes encoding for tRNA nucleotidyltransferases. Such pairs of tRNA nucleotidyltransferases usually represent collaborating partial activities catalyzing CC- and A-addition to the tRNA 3′-end, respectively. In D. discoideum, however, both enzymes exhibit identical activities, representing bona-fide CCA-adding enzymes. Detailed characterization of the corresponding activities revealed that both enzymes seem to be essential and are regulated inversely during different developmental stages of D. discoideum. Intriguingly, this is the first description of two functionally equivalent CCA-adding enzymes using the same set of tRNAs and showing a similar distribution within the cell. This situation seems to be a common feature in Dictyostelia, as other members of this phylum carry similar pairs of tRNA nucleotidyltransferase genes in their genome.

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Section: Discussionmentioning

confidence: 99%

Unusual Occurrence of Two Bona-Fide CCA-Adding Enzymes in Dictyostelium discoideum

Erber

Hoffmann

Fallmann

et al. 2020

IJMS

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“…The complete protein import system consists of three outer membrane (TOM, TOB/SAM, MIM), four inner membrane (TIM22, TIM23, TIM23+PAM, OXA) and three mitochondrial intermembrane space assembly (MIA) complexes. Comparative sequence analysis of genome and transcriptome data by Wojtkowska et al, (2017) indicates that in D. discoideum, protein import complexes of the canonical Saccharomyces appear to be conserved with the exception of MIA (albeit with some subunit variation/loss) ( Fig. 1).…”

Section: Protein Importmentioning

confidence: 99%

“…Most protein import from the cytosol through the outer mitochondrial membrane (OMM) is facilitated by the TOM complex (Rapaport, 2002). In D. discoideum, the TOM complex consists of Tom 7, 20, 22, 40, 70 (Macasev et al, 2004, Wojtkowska et al, 2017. Tom22 and Tom40 are conserved in all eukaryotes with the addition of Tom7 after the divergence of the Excavates supergroup (Mani et al, 2016).…”

Section: Protein Importmentioning

confidence: 99%

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The Dictyostelium model for mitochondrial biology and disease

Pearce¹,

Annesley²,

Fisher³

2019

Int. J. Dev. Biol.

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The unicellular slime mould Dictyostelium discoideum is a valuable eukaryotic model organism in the study of mitochondrial biology and disease. As a member of the Amoebozoa, a sister clade to the animals and fungi, Dictyostelium mitochondrial biology shares commonalities with these organisms, but also exhibits some features of plants. As such it has made significant contributions to the study of eukaryotic mitochondrial biology. This review provides an overview of the advances in mitochondrial biology made by the study of Dictyostelium and examines several examples where Dictyostelium has and will contribute to the understanding of mitochondrial disease. The study of Dictyostelium's mitochondrial biology has contributed to the understanding of mitochondrial genetics, transcription, protein import, respiration, morphology and trafficking, and the role of mitochondria in cellular differentiation. Dictyostelium is also proving to be a versatile model organism in the study both of classical mitochondrial disease e.g. Leigh syndrome, and in mitochondria-associated neurodegenerative diseases like Parkinson's disease. The study of mitochondrial diseases presents a unique challenge due to the cryptic nature of their genotypephenotype relationship. The use of Dictyostelium can contribute to resolving this problem by providing a genetically tractable, haploid eukaryotic organism with a suite of readily characterised phenotype readouts of cellular signalling pathways. Dictyostelium has provided insight into the signalling pathways involved in multiple neurodegenerative diseases and will continue to provide a significant contribution to the understanding of mitochondrial biology and disease.

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“…However, in the case of other eukaryotes, smaller or bigger differences in the complex subunits have been reported. For example, the animal TOB/SAM complex contains metaxin-2 as a counterpart of Tob38/Sam35, as well as metaxin-1 and metaxin-3 as counterparts of Mas37/Sam37 (Sokol et al, 2014), whereas the subunits predicted for the complex of the slime mold D. discoideum include Tob55/ Sam50 and metaxin as a sole receptor subunit (Buczek et al, 2016;Wojtkowska et al, 2017). It is assumed that the monomeric form of the TOB/SAM complex, composed of the main subunits, has molecular weight of 160-250 kDa, depending on the studied organism (e.g.…”

Section: Introductionmentioning

confidence: 99%

The The TOB/SAM complex composition in mitochondria of Dictyostelium discoideum during progression from unicellularity to multicellularity

et al. 2019

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Despite its complex life cycle including unicellular and multicellular stages, the slime mold Dictyostelium discoideum, a well-known model in biomedical research, has not been used as a model organism in studies on mitochondrial import, including its significance in cellular processes. Moreover, data concerning mitochondrial protein import machinery in D. discoideum mitochondria is limited and nothing is known about the impact of that machinery on slime mold life cycle. Here, we focused on the TOB/SAM (topogenesis of the mitochondrial outer membrane β-barrel proteins/sorting and assembly machinery) complex. This complex is localized in the mitochondrial outer membrane and is indispensable for the formation of metabolite exchange and protein import pathways in the membrane, and substantially contributes to the regulation of mitochondrial morphology and distribution. Furthermore, the available data suggests that the TOB/SAM complex variants differ between mitochondria of multicellular and unicellular eukaryotes. Therefore, we decided to determine these variants of the TOB/SAM in mitochondria of D. discoideum progressing from single cells to early multicellular stages, when the cells stream together to form a multicellular organism. The results revealed two complex variants of the TOB/SAM complex of about 160 and 600 kDa molecular weight, present in mitochondria of D. discoideum cells at the studied stages. The discussed complex variants resemble the ones that have been already detected for the yeast Saccharomyces cerevisiae, fungus Neurospora crassa and human cells, and one of investigated variants differentiates unicellular and initial multicellular stages of the D. discoideum life cycle.

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The emerging picture of the mitochondrial protein import complexes of Amoebozoa supergroup

Cited by 8 publications

References 52 publications

Unusual Occurrence of Two Bona-Fide CCA-Adding Enzymes in Dictyostelium discoideum

Unusual Occurrence of Two Bona-Fide CCA-Adding Enzymes in Dictyostelium discoideum

The Dictyostelium model for mitochondrial biology and disease

The The TOB/SAM complex composition in mitochondria of Dictyostelium discoideum during progression from unicellularity to multicellularity

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