TABLE 2.
Transient kinetic parameters obtained in the present study for Drosophila nonmuscle myosin-2 S1
| Parameter | Signal or calculation | Drosophila nonmuscle myosin-2 | Acanthamoeba nonmuscle myosin-2 (23) | Dictyostelium nonmuscle myosin-2 (24, 26–28) | Human nonmuscle myosin-2A (25) |
|---|---|---|---|---|---|
| ATP interaction | |||||
| K1k+2 (µM−1 s−1) | Tryptophan | 1.16 ± 0.06 | 1.33 ± 0.04 | 0.86 | 0.56 ± 0.01 |
| K1k+2 (µM−1 s−1) | d-mantATP | 0.94 ± 0.02 | 1.93 ± 0.02 | 1.13 | 1.03 ± 0.14 |
| 1/K1 (µM) | Tryptophan | 3.73 ± 1.32 | 5.19 ± 0.58 | 25.8 | n.d. |
| k3 + k-3 (s−1) | Tryptophan | 11.65 ± 0.56 | 19.0 ± 0.5 | 30 | 14.1 ± 0.5 |
| K1k+2 (µM−1 s−1) | Pyrene-actin | 0.39 ± 0.01 | 2.11 ± 0.03 | 0.25 | 0.21 ± 0.04 |
| K1k+2 (µM−1 s−1) | Light scattering | 0.34 ± 0.01 | 0.73 ± 0.02 | n.d. | 0.14 ± 0.003 |
| 1/K1 (µM) | Pyrene-actin | 1222.3 ± 60.29 | 651.3 ± 68.4 | 509 | ∼900 |
| k+2 (s−1) | Pyrene-actin | 482.80 ± 7.85 | 779.6 ± 24.9 | 380 | ∼190 |
| ADP interaction | |||||
| k+D (µM−1 s−1) | d-mantADP | 0.52 ± 0.04 | 0.50 ± 0.03 | 1.02 | 0.55 ± 0.06 |
| k−D (s−1) | d-mantADPa | 2.42 ± 0.13 | 2.29 ± 0.20 | n.d. | 0.54 ± 0.23 |
| k−D (s−1) | d-mantADPb | 2.92 ± 0.03 | 1.53 ± 0.01 | 1.6 | 1.12 ± 0.13 |
| k−D (s−1) | Tryptophanb | 2.35 ± 0.01 | 1.68 ± 0.02 | n.d. | n.d. |
| KD (µM) | k−D/k+D | 4.65 ± 0.44 | 4.58 ± 0.49 | 1.6 | 1.5 ± 0.4 |
| k+AD (µM−1 s−1) | d-mantADP | 3.46 ± 0.11 | ∼4.95c | 0.72 | 2.72 ± 0.16 |
| k−AD (s−1) | d-mantADP a | 5.19 ± 0.55 | n.d. | n.d. | n.d. |
| k−AD (s−1) | Pyrene-actinb | 5.53 ± 0.08 | 28.9 ± 0.07 | 15 | n.d. |
| k−AD (s−1) | Light scatteringb | 4.27 ± 0.05 | 29.67 ± 0.15 | n.d. | n.d. |
| k−AD (s−1) | d-mantADPb | 5.06 ± 0.05 | 31.43 ± 0.49 | n.d. | 2.68 ± 0.30 |
| KAD (µM) | k−AD/k+AD | 1.5 ± 0.17 | 5.99 ± 0.88 | 58 | 1.4 ± 0.4 |
| Coupling | KAD/KD | 0.32 ± 0.05 | 1.30 ± 0.24 | ∼36 | 0.7 |
| Coupling | k−AD/k−D | 2.14 ± 0.25 | ∼17.6 | ∼9.4 | 2.8 |
| Actin interaction | |||||
| k+A (µM−1 s−1) | Light scattering | 1.14 ± 0.03 | 10.88 ± 0.22 | 1.34 | 0.73 ± 0.03 |
| k−A (s−1) | Pyrene-actin | ∼0.07 | ∼0.001 | 0.0068 | <0.007 |
| KA (nM) | k−A/k+A | ∼60 | ∼0.1 | ∼5.1 | <10 |
| k+DA (µM−1 s−1) | Light scattering | 0.26 ± 0.01 | 1.17 ± 0.04 | n.d. | 0.19 ± 0.02 |
| k−DA (s−1) | Pyrene-actin | ∼0.01 | ∼0.014 | n.d. | ∼0.004 |
| KDA (nM) | k−DA/k+DA | ∼38 | ∼12 | n.d. | ∼20 |
For comparison, the kinetic parameters from selected nonmuscle myosin-2s are listed. n.d., not determined. aFrom y-intercept. bFrom chasing experiment. cCalculation from k−AD/KAD.