Milligram quantities of Zaire ebolavirus nonstructural, secreted glycoprotein (sGP) were purified to homogeneity, and this preparation was characterized by an array
of biophysical and biochemical experiments. Massspectrometry analysis revealed sGP posttranslational modifications and regions
susceptible to limited proteolysis. In solution, sGP has an absolute molar mass of 103 kDa, is
... [Show full abstract] monodisperse, and folds into
a predominantly β-sheet conformation with a distinct tertiary structure. sGP appears to have a unique free-energy landscape
that facilitates reversible folding and a strong propensity for disulfide-linked dimeric quaternary structure under a wide
range of conditions; the low apparent free energy of conformation transition of sGP (ΔG = 1.7±0.1 kcal/mol) suggests that the molecule is well suited as a thermodynamically facile switch, which would allow it
to report on relatively subtle changes in milieu. In addition, a conformational transition at 37°C was detected in thermal
denaturing experiments. On the basis of biophysical and biochemical considerations alone, we propose that the property of
being a thermodynamically facile switch is an important clue to reveal sGP functionality.
