Fig. 4

Rieske proteins as putative substrate of mitochondrial TAT. a The experimental signal peptides of A. godoyi and N. gruberi Rieske proteins. Ag/NgRieske signal sequences fused to mature AmiA expressed from pSU18 are translocated through bacterial membrane in both absence (1; pTH19kr) and presence (2; pTAT101) of TAT in MCDSSAC Δtat strain. (3) SufI signal sequence fused to mature AmiA expressed from pSU18 is not translocated in the absence of TAT (pTH19kr) in MCDSSAC Δtat strain. b Protein sequence alignment of the Rieske protein orthologues shows the presence of putative twin arginine motif in both TAT-positive (TatAC in A. godoyi and R. americana, TatBC in A. thaliana, TatC-only in N. gruberi and O. carmella) and TAT-negative eukaryotes (H. sapiens). The blue rectangle highlights the presence of twin arginine (RR) or derived (KR and RK) motifs, and the green rectangle depicts the transmembrane domain. Identical and similar residues are highlighted in pink and grey colour, respectively. The threshold for shading was 50%