Arabidopsis DGD1 SUPPRESSOR1 Is a Subunit of the Mitochondrial Contact Site and Cristae Organizing System and Affects Mitochondrial Biogenesis

Abstract

Mitochondrial and plastid biogenesis requires the biosynthesis and assembly of proteins, nucleic acids, and lipids. In Arabidopsis (Arabidopsis thaliana), the mitochondrial outer membrane protein DGD1 SUPPRESSOR1 (DGS1) is part of a large multi-subunit protein complex that contains the mitochondrial contact site and cristae organizing system 60-kD subunit, the translocase of outer mitochondrial membrane 40-kD subunit (TOM40), the TOM20s, and the Rieske FeS protein. A point mutation in DGS1, dgs1-1, altered the stability and protease accessibility of this complex. This altered mitochondrial biogenesis, mitochondrial size, lipid content and composition, protein import, and respiratory capacity. Whole plant physiology was affected in the dgs1-1 mutant as evidenced by tolerance to imposed drought stress and altered transcriptional responses of markers of mitochondrial retrograde signaling. Putative orthologs of Arabidopsis DGS1 are conserved in eukaryotes, including the Nuclear Control of ATP Synthase2 (NCA2) protein in yeast (Saccharomyces cerevisiae), but lost in Metazoa. The genes encoding DGS1 and NCA2 are part of a similar coexpression network including genes encoding proteins involved in mitochondrial fission, morphology, and lipid homeostasis. Thus, DGS1 links mitochondrial protein and lipid import with cellular lipid homeostasis and whole plant stress responses.

The draft nuclear genome sequence and predicted mitochondrial proteome of Andalucia godoyi, a protist with the most gene-rich and bacteria-like mitochondrial genome

“…We additionally found a Cox17 ortholog, a CIV assembly protein (see Table 3) missed by Muñoz-Gómez et al [132]. The ATPase assembly factor Nca2 (see Table 3) may also be functionally linked to MICOS in Andalucia, analogously to the role of its plant ortholog [136].…”

The Plant Mitochondrial TAT Pathway Is Essential for Complex III Biogenesis

“…Although these data just provide two-dimensional information on the mitochondrial structure, they establish an interesting potential connection between RISP assembly and cristae organization and mitochondrial shape in plants. However, RISP was also recently found to be associated with the mitochondrial contact site and cristae organizing system (MICOS) complex of plant mitochondria [39], suggesting a potentially greater (G) Free cysteine labeling was performed by pegylation of intact Mit, TCA-precipitated mitochondria, and Mit*OM with mm(PEG) 24 . TOM20 and MPPa served as labeling controls.…”

Conserved and Opposite Transcriptome Patterns during Germination in Hordeum vulgare and Arabidopsis thaliana

“…Additionally, 400 orthogroups containing genes encoding mitochondrial proteins displayed a conserved pattern of up- or downregulation of abundance during germination ( Table S11A,B ). Nevertheless, some differences were also observed including those for certain genes whose transcript abundances were downregulated in Arabidopsis but whose orthologue(s) were upregulated in barley, with these encoded proteins being associated with mitochondrial DNA repair (At3g20540, At1g50840 polymerase gamma), 25 PPR or TPR proteins, lipid synthesis (DGD1_UDP-glycosyltransferase, cardiolipin synthase), dynamin-related proteins 3A and 3B, and elongated mitochondria1 (ELM1) involved in mitochondrial fission ([ 58 ] and DGS1 (dgd1 suppressor 1), which is involved in both lipid and protein biogenesis in plant mitochondria [ 59 ]. This suggests that these processes may be already established in Arabidopsis, while in barley they are still actively occurring.…”