PMC

Figure 1. Diversity and conservation of SDHAF2-like protein sequences. (A) Phylogenetic tree analysis of SDHAF2-like protein sequences. The protein accession numbers of SDHAF2-like proteins used for analysis are: Homo sapiens, NP_060311; Mus musculus, NP_079609; Saccharomyces cerevisiae, B3LIY9; Serratia ATCC 39006, G4V4G2; Physcomitrella patens, XP_001752564; Ostreococcus tauri, XP_003074399; Chlamydomonas reinhardtii, XP_001694005; Glycine max, NP_001236603; Medicago truncatula, XP_003602736; Ricinuscommunis, XP_002511076; Arabidopsis thaliana, At5g51040; Vitis Vinifera, XP_003635192; Hordeum vulgare, BAJ90590; Brachypodium distachyon, XP_003577516; Oryza sativa, Os11 g32480; Zea mays, ACG26201; Sorghum bicolor, XP_002449598. (B) Sequence alignment of conserved regions containing a glycine residue (red arrow) required for flavinylation.

Figure 2. C-terminal tail sequences of SDH1 required for flavinylation. (A) Sequence alignment of C-terminal tail of SDH1 in plants, human and yeast. Red arrows indicate arginine residues required for flavinylation in yeast. The blue arrow indicate the mutation site of Arabidopsis SDH1–1 (At5g66760) indsr1. The protein sequences used for alignments are: Arabidopsis thaliana (At5g66760), Oryza sativa (Os07 g04240); Homo sapiens, P31040; Saccharomyces cerevisiae, Q00711. (B) Flavinylated SDH1is indicated by the red arrow in Arabidopsis mitochondrial protein extracts from dsr1, WT and sdhaf2. The protein bound-flavin assay was conducted as described in Huang et al. After SDS-PAGE separation of mitochondria proteins, the protein bands with bound-flavin before and after 10% acetic acid treatment for 30 min were scanned using a Typhoon Trio laser imager (GE Healthcare) with excitation at 488 nm and emission at 526 nm. The protein bands containing bound-FAD are indicated by the red arrow.