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  • The Plant Mitochondrial TAT Pathway Is Essential for Complex III Biogenesis.

The Plant Mitochondrial TAT Pathway Is Essential for Complex III Biogenesis.

Current biology : CB (2020-02-23)
Kerstin Schäfer, Patrick Künzler, Katja Schneider, Andreas Klingl, Holger Eubel, Chris Carrie
ABSTRACT

Twin arginine translocation (TAT) pathways have been extensively studied in bacteria and chloroplasts for their role in membrane translocation of folded proteins. However, an increasing number of organisms have been found to contain mitochondria-located TAT subunits, including plant mitochondria, which contain TAT subunits, though in an unusual arrangement with only TatB and TatC subunits. To date, no confirmed function has been attributed to mitochondrial TAT pathways in any organism. Using a truncation mutant approach, we demonstrate that the plant mitochondrial TatB (MTTATB) is required for complex III biogenesis. More specifically, MTTATB performs at a late stage in complex III biogenesis, conveying the translocation of the C terminus of the Rieske FeS subunit back across the inner membrane. This work confirms that plant mitochondria retained a functional TAT pathway for the Rieske FeS translocation, most likely from the original mitochondrial ancestor. It is hypothesized that the original mitochondria contained a bacteria-derived TAT pathway required for at least the Rieske FeS translocation. In several eukaryotic lineages, this mitochondrial TAT pathway was lost and replaced by BCS1. Interestingly, plant mitochondria appear to assemble complex III in the same subunit order as yeast and mammals but in contrast use bacteria-like assembly factors for this process.

MATERIALS
Product Number
Brand
Product Description

Supelco
Diuron-d6, PESTANAL®, analytical standard
Sigma-Aldrich
Anti-Chicken IgY (IgG) (whole molecule)−Peroxidase antibody produced in rabbit, IgG fraction of antiserum, buffered aqueous solution
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Cytochrome c from bovine heart, ≥95% based on Mol. Wt. 12,327 basis, powder, suitable for mammalian cell culture