TABLE 1.
Biophysical characterization of HBx, DDB1, and HBx-DDB1 complexesa
| Protein(s) | Species determined by AUC (%) |
%Pd by DLS | Mean molar ratio by ICP-MS ± SEMc
|
Detergent required for solubility | ||
|---|---|---|---|---|---|---|
| Main speciesb | Other species | Zn/protein | Fe/protein | |||
| DDB1 | 6.4S (99) | 10.9S (1) | 9 | ≤0.2 ± 0.1f | ≤0.1 ± 0.1f | No |
| HBx | 1.6S (80) | 3.5S (7) | ND | 0.0 ± 0.0f | 0.0 ± 0.0f | Yesd |
| HBx:DDB1 coexpressed | 6.6S (99) | 9.9S (1) | 12 | 0.7 ± 0.1 | ≤0.1 ± 0.1f | No |
| HBx-DDB1 fusion | 6.8S (92.4) | 10.4S (6.7) | 19 | 1.3 ± 0.2 | ≤0.1 ± 0.0f | No |
| HBxCCCH-DDB1 fusione | ND | ND | ND | 0.3 ± 0.0 | ≤0.1 ± 0.0f | No |
| SV5-V | 2.1S (94.7) | 5.2S (2) | 18 | 1.9 ± 0.1 | 0.0 ± 0.0f | No |
a
AUC, analytical ultracentrifugation; DLS, dynamic light scattering; %Pd, percent polydispersity; ND, not determined.
b
The main species was a monomer of each protein or a one-to-one complex in the case of the HBx:DDB1 coexpressed construct.
c
ICP-MS (inductively coupled plasma mass spectrometry) data are expressed as mean molar ratios ± SEM (n = 2 to 7 independent experiments).
d
HBx expressed alone required 0.01% Fos-choline 14 for solubilization.
e
HBxCCCH refers to the HBx C61A/C69A/C137A/H139A mutant protein.
f
Values represent the limit of quantitation.