Protein import complexes in the mitochondrial outer membrane of Amoebozoa representatives

Abstract

BackgroundAn ancestral trait of eukaryotic cells is the presence of mitochondria as an essential element for function and survival. Proper functioning of mitochondria depends on the import of nearly all proteins that is performed by complexes located in both mitochondrial membranes. The complexes have been proposed to contain subunits formed by proteins common to all eukaryotes and additional subunits regarded as lineage specific. Since Amoebozoa is poorly sampled for the complexes we investigated the outer membrane complexes, namely TOM, TOB/SAM and ERMES complexes, using available genome and transcriptome sequences, including transcriptomes assembled by us.ResultsThe results indicate differences in the organization of the Amoebozoa TOM, TOB/SAM and ERMES complexes, with the TOM complex appearing to be the most diverse. This is reflected by differences in the number of involved subunits and in similarities to the cognate proteins of representatives from different supergroups of eukaryotes.ConclusionsThe obtained results clearly demonstrate structural variability/diversity of these complexes in the Amoebozoa lineage and the reduction of their complexity as compared with the same complexes of model organisms.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2402-2) contains supplementary material, which is available to authorized users.

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

“…Interestingly, in the 160 kDa complex, we detected Mdm10, but not the Tom40 protein (Table 1). Notably, Mdm10 had been previously predicted in D. discoideum by bioinformatics analysis (Buczek et al, 2016) but at a protein level it was confirmed for the first time in this study (Table S2 at https://ojs.ptbioch.edu.pl/).…”

“…As we had previously predicted the main subunits of the D. discoideum TOB/SAM complex using available genomic and transcriptomic sequences (Wojtkowska et al, 2012;Buczek et al, 2016), we decided to confirm the presence of the Tob55/Sam50 and metaxin subunits at a protein level. The designed polyclonal antibody against Tob55/Sam50 (Materials and Methods) was used to confirm the presence of Tob55/Sam50 in mitochondria of intact cells at the studied stages (Fig.…”

“…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.…”

Novel Hydrogenosomes in the Microaerophilic JakobidStygiella incarcerata

“…Dark blue: free-living mitochondrion; pale blue: free-living MRO; dark pink: parasite, mitochondrion; light pink, parasite, MRO; purple: facultative parasite, mitochondrion; dark grey: bacterium; pale grey: incomplete data. Data from Neupert (1997) , Hoogenraad et al (2002) , Henriquez et al (2005) , Regoes et al (2005) , van der Laan et al (2005) ; Williams and Keeling (2005) , Dolezal et al (2006) , Figueroa-Martinez et al (2008) , Atteia et al (2009) , Dagley et al (2009) , Waller et al (2009) , Barberà et al (2010) , Dolezal et al (2010) , Jedelsky et al (2011) , Liu et al (2011) , Schneider et al (2011) , Eckers et al (2012) , Pusnik et al (2012) , Basu et al (2013) , Heinz and Lithgow (2013) , Jerlstrom-Hultqvist et al (2013) , Wideman et al (2013) , Zubacova et al (2013) , Gawryluk et al (2014) , Murcha, Kmiec, et al 2014 ; Murcha, Wang, et al 2014 ; Stairs et al (2014) , Martincova et al (2015) , Murcha et al (2015) , Noguchi et al (2015) , Wojtkowska et al (2015) , and Buczek et al (2016) this study. 1 Transcriptome data, incomplete, particularly in the cases of S. marylandensis and Paratrimastix pyriformis ; 2 pATOM36; 3 Tom9; 4 pATOM; 5 Metaxin 6 Tim8/13; 7 Tim17/22/23.…”

Molecular evolution of proteins mediating mitochondrial fission–fusion dynamics

“…Mitochondria are dynamic, bilayered membrane-bound, self-replicating, energy-producing organelles of eukaryotic cells derived from the endosymbiosis of purple non-sulfur bacteria by an ancestral host cell [1][2][3][4][5][6]. Subsequent to the endosymbiotic event, mitochondria have undergone substantial evolution in terms of metabolic capabilities and ultrastructure [7][8][9][10][11]. The Dynaminrelated proteins (DRPs) that belong to the Dynamin superfamily are essential to determine the mitochondrial shape and to regulate remodeling by mediating membrane fission-fusion dynamics [12][13][14][15][16].…”