Association of high pressure and alkaline condition for solubilization of inclusion bodies and refolding of the NS1 protein from zika virus.
BACKGROUND
Proteins in inclusion bodies (IBs) present native-like secondary structures. However, chaotropic agents at denaturing concentrations, which are widely used for IB solubilization and subsequent refolding, unfold these secondary structures. Removal of the chaotropes frequently causes reaggregation and poor recovery of bioactive proteins. High hydrostatic pressure (HHP) and alkaline pH are two conditions that, in the presence of low level of chaotropes, have been described as non-denaturing solubilization agents. In the present study we evaluated the strategy of combination of HHP and alkaline pH on the solubilization of IB using as a model an antigenic form of the zika virus (ZIKV) non-structural 1 (NS1) protein.


RESULTS
Pressure-treatment (2.4 kbar) of NS1-IBs at a pH of 11.0 induced a low degree of NS1 unfolding and led to solubilization of the IBs, mainly into monomers. After dialysis at pH 8.5, NS1 was refolded and formed soluble oligomers. High (up to 68 mg/liter) NS1 concentrations were obtained by solubilization of NS1-IBs at pH 11 in the presence of arginine (Arg) with a final yield of approximately 80% of total protein content. The process proved to be efficient, quick and did not require further purification steps. Refolded NS1 preserved biological features regarding reactivity with antigen-specific antibodies, including sera of ZIKV-infected patients. The method resulted in an increase of approximately 30-fold over conventional IB solubilization-refolding methods.


CONCLUSIONS
The present results represent an innovative non-denaturing protein refolding process by means of the concomitant use of HHP and alkaline pH. Application of the reported method allowed the recovery of ZIKV NS1 at a condition that maintained the antigenic properties of the protein.
['Rosa da Silva|Cleide Mara|CM|', 'Chura-Chambi|Rosa Maria|RM|', 'Ramos Pereira|Lennon|L|', 'Cordeiro|Yraima|Y|', 'de Souza Ferreira|Luís Carlos|LC|', 'Morganti|Ligia|L|0000-0002-7870-1793']
D000468:Alkalies D001671:Biochemistry D006874:Hydrostatic Pressure D002479:Inclusion Bodies D058849:Protein Refolding D017433:Protein Structure, Secondary D012995:Solubility D017361:Viral Nonstructural Proteins D000071244:Zika Virus
Inclusion bodies NS1 High hydrostatic pressure Alkaline pH Protein refolding Dengue virus and Zika virus