Interaction energy and salt bridge formation between actin, tropomyosin (Tpm), and the C-terminal domain of TnI
| . | Interaction energies (kcal/mol) . | Intermolecular salt bridges . | |
|---|---|---|---|
| Coulombic | van der Waals | n residues involved | |
| C-state | |||
| Actin–Tpm pseudorepeat 2 | −50 | −23 | 1 |
| Actin—Tpm pseudorepeat 3 | −414 | 9 | 2 |
| Actin—Tpm pseudorepeat 4 | −481 | −18 | 5 |
| Actin—Tpm pseudorepeat 5 | −242 | −16 | 4 |
| Actin—Tpm pseudorepeat 6 | −545 | −14 | 6 |
| Actin—C-terminal TnI | — | — | — |
| Tpm—C-terminal TnI | — | — | — |
| Total | −1,732 | −62 | 18 |
| B-state | |||
| Actin–Tpm pseudorepeat 2 | −154 | 4 | 3 |
| Actin—Tpm pseudorepeat 3 | −248 | −26 | 2 |
| Actin—Tpm pseudorepeat 4 | −285 | −8 | 1 |
| Actin—Tpm pseudorepeat 5 | −328 | −13 | 4 |
| Actin—Tpm pseudorepeat 6 | −498 | −1 | 4 |
| Actin—C-terminal TnI | −65 | −95 | 7 |
| Tpm—C-terminal TnI | −348 | −54 | 12 |
| Total | −1,926 | −193 | 33 |
| . | Interaction energies (kcal/mol) . | Intermolecular salt bridges . | |
|---|---|---|---|
| Coulombic | van der Waals | n residues involved | |
| C-state | |||
| Actin–Tpm pseudorepeat 2 | −50 | −23 | 1 |
| Actin—Tpm pseudorepeat 3 | −414 | 9 | 2 |
| Actin—Tpm pseudorepeat 4 | −481 | −18 | 5 |
| Actin—Tpm pseudorepeat 5 | −242 | −16 | 4 |
| Actin—Tpm pseudorepeat 6 | −545 | −14 | 6 |
| Actin—C-terminal TnI | — | — | — |
| Tpm—C-terminal TnI | — | — | — |
| Total | −1,732 | −62 | 18 |
| B-state | |||
| Actin–Tpm pseudorepeat 2 | −154 | 4 | 3 |
| Actin—Tpm pseudorepeat 3 | −248 | −26 | 2 |
| Actin—Tpm pseudorepeat 4 | −285 | −8 | 1 |
| Actin—Tpm pseudorepeat 5 | −328 | −13 | 4 |
| Actin—Tpm pseudorepeat 6 | −498 | −1 | 4 |
| Actin—C-terminal TnI | −65 | −95 | 7 |
| Tpm—C-terminal TnI | −348 | −54 | 12 |
| Total | −1,926 | −193 | 33 |
Electrostatic and van der Waals interactions between different thin filament pseudorepeat segments defined by B-state (PDB ID 7UTL) and C-state (PDB ID 7UTI) atomic models were measured in VMD (Humphrey et al., 1996). Salt bridges attributed to the above segments were also counted using tip-to-tip inter-residue cutoff of 5.5 Å. Values were tabulated for tropomyosin pseudorepeats 2–6 neighboring TnI. Data reported for C-terminal TnI interactions were acquired for TnI residues 149 to 210, which includes the switch-peptide, H4 helix, and C-terminal domain of TnI (as defined by Marston and Zamora, 2020).