TABLE 2.
Best fit parameters for the PCNA loading mechanism
| Parameters (units) | PCNAWC | PCNAWC-R80A | Event |
|---|---|---|---|
| k1 (μm−1 s−1)/k−1 (s−1) | 100/100 | 100/100 | ATP binding/dissociation |
| Kd1 (μm) | 1 | 1 | |
| k2 (μm−1 s−1)/k−2 (s−1) | 200/10 | 200/10 | PCNA binding/dissociation |
| Kd2 (μm) | 0.05 | 0.05 | |
| k3 (s−1)a/k−3 (s−1)a | 13 ± 0.2/0.26 ± 0.004e | 13 ± 0.6/0.26 ± 0.01 | RFC activation |
| k4 (s−1)a | 3.2 ± 0.05 | 3.2 ± 0.15 | PCNA opening |
| k5 (μm−1 s−1)b/k−5 (s−1)b | 105 ± 4/0.2 ± 0.008 | 17.5 ± 1.3/0.03 ± 0.002 | RFC·ATP·PCNA ptDNA binding/dissociation |
| k6 (μm−1 s−1)c/k−6 (s−1)c | 117 ± 4/0.2 ± 0.008 | 40 ± 0.7/0.08 ± 0.001 | RFC·ATP·PCNAopen ptDNA binding/dissociation |
| Kd5 or Kd6 (μm) | 0.002 | 0.002 | |
| k7 (s−1) | 25 | 25 | ATP hydrolysis |
| k8 (s−1) | 5.1 ± 0.05 | 2.8 ± 0.04 | RFC deactivation and PCNA closure |
| k9 (s−1) | 500 | 500 | PCNA·ptDNA release from RFC |
| k10 (s−1) | 500 | 500 | Pi release |
| k11 (s−1) | 0.7 ± 0.03 | 1.8 ± 0.08 | PCNA·ptDNA dissociation |
| k12 (s−1)d/k−12 (s−1)d | 21 ± 0.6/0.9 ± 0.02 | 17 ± 0.9/0.32 ± 0.02 | PCNA/PCNA** equilibrium |
| N | 2.7 ± 0.01 | 2.3 ± 0.03 | Number of ATP hydrolyzed rapidly per RFC |
a–d Each label specifies parameters that were linked during global fitting analysis.
e Standard error values are shown for parameters allowed to float during data fitting.
** indicates loading-inactive PCNA.