Table 2. Consistent findings across multiple functional assays for each variant in our yeast model.
A summary of results including the growth on glycerol, oxygen consumption, Sdh2 protein abundance, consequences of changing the WT amino acid using computational modeling and literature search for studies in other species’ flavoprotein are tabulated along with our classification of each variant based on our yeast model. The no effect variants are highlighted in grey for clarity. Numerical values for oxygen consumption were taken from Figure 1C and D. Numerical values for Sdh2 protein were taken from Figure 2E.
| hSDHA mutation | ySdh1 mutation | Growth phenotype on glycerol | Oxygen consumption (% of complemented) | Sdh2 protein (% of complemented) | Structural implications of variants | Group name |
|---|---|---|---|---|---|---|
| R31X (control) | R19X (control) | Unable to grow | Decreased (20%) | Decreased (0%) | Truncates mitochondrial targeting sequence (47) | Loss-of-function (control) |
| H99S (control) | H90S (control) | Unable to grow | Decreased (−2%) | Decreased (15%) | Inhibits covalent bond to FAD (14) | Loss-of-function (control) |
| G106R | G97R | Unable to grow | Decreased (7%) | Decreased (14%) | Distorts the active site (31) | Loss-of-function |
| N118S | N109S | Growth | Similar (108%) | Similar (83%) | Surface of protein | No effect |
| T143M | T134M | Unable to grow | Decreased (3%) | Decreased (35%) | No obvious disturbances but causes loss of function | Loss-of-function |
| R171H | R162H | Growth | Similar (84%) | Similar (78%) | Surface of protein | No effect |
| R188W | R179W | Unable to grow | Decreased (21%) | Decreased (0%) | Disrupts salt bridge with D108 | Loss-of-function |
| R195W | R186W | Growth | Similar (91%) | Similar (82%) | Surface of protein | No effect |
| G260R | G251R | Unable to grow | Decreased (27%) | Decreased (0%) | Obstructs flavin binding pocket | Loss-of-function |
| H296Y | H287Y | Unable to grow | Decreased (4%) | Decreased (11%) | Inhibits succinate binding (31) | Loss-of-function |
| R312C | R303C | Unable to grow | Decreased (4%) | Decreased (3%) | Contributes to proper orientation and activation of the flavin isoalloxazine ring to facilitate formation of the covalent FAD bond and disrupts salt bridge (48) | Loss-of-function |
| R408C | Y399C | Unable to grow | Decreased (9%) | Decreased (4%) | In flavin binding site | Loss-of-function |
| G419R | G410R | Unable to grow | Decreased (19%) | Decreased (2%) | Distorts helix | Loss-of-function |
| C438F | C431F | Unable to grow | Decreased (19%) | Decreased (2%) | Bulky change disrupts helix | Loss-of-function |
| G439E | G432E | Unable to grow | Decreased (−2%) | Decreased (3%) | Obstructs flavin binding pocket | Loss-of-function |
| R451C | R444C | Unable to grow | Decreased (12%) | Decreased (6%) | Disrupts flavin binding, succinate binding and proton shuttle necessary for catalytic activity (31) | Loss-of-function |
| R451H | R444H | Unable to grow | Decreased (3%) | Decreased (0%) | Disrupts flavin binding, succinate binding and proton shuttle necessary for catalytic activity (31) | Loss-of-function |
| A454E | A447E | Unable to grow | Decreased (11%) | Decreased (0%) | Lines succinate binding site (31) | Loss-of-function |
| R465W | R458W | Unable to grow | Decreased (5%) | Decreased (21%) | Disrupts salt bridge with E136 | Loss-of-function |
| T508I | T501I | Growth | Similar (113%) | Similar (75%) | Surface of protein | No effect |
| R589G | R582G | Unable to grow | Decreased (12%) | Decreased (0%) | Inhibits C-terminal flavination (25) | Loss-of-function |
| H625W | H601Y | Unable to grow | Decreased (18%) | Decreased (2%) | Inhibits C-terminal flavination | Loss-of-function |
| Y629F | W605F | Growth | Similar (113%) | Similar (101%) | Surface of protein | No effect |
| V657I | V633I | Growth | Similar (108%) | Similar (82%) | Surface of protein | No effect |