Expression, Purification and Structural Characterization of Up-Regulated Gene 7 Encoded Protein
Angela Ostuni, Maria Antonietta Castiglione Morelli, Rocchina Miglionico, Antonella Maria Salvia, Flavia Cuviello and Faustino Bisaccia
Affiliation: Department of Sciences, University of Basilicata, Viale dell'Ateneo Lucano 10, 85100 Potenza, Italy.
Up-Regulated Gene 7 (URG7) is a host gene up-regulated in HBV infected hepatocytes that has been suggested
to have an anti-apoptotic activity mediated by caspases 3 and 8 and an endoplasmic reticulum localization. Here we report
the structural characterization of the encoded protein URG7 by circular dichroism and fluorescence spectroscopy in different
solvent media: phosphate buffer and two membrane-mimetic solvents, i.e. 2,2,2-trifluoroethanol (TFE) and SDS
micelles. In all solvents URG7 contains substantial amounts of secondary structures. To obtain information about the
structural organization and stability of URG7, its thermal denaturation in a membrane environment was studied and intermediate
states of thermal unfolding were observed. Furthermore, fluorescence results in SDS micelles could be compatible
with different environments for the four tryptophan residues in URG7. Preliminary NMR data indicate that URG7
in TFE solution is quite flexible and not well folded. These data are the first structural information on URG7 and might
provide an insight into its structure-function relationships.
Keywords: Circular dichroism, fluorescence, hepatocellular carcinogenesis, NMR, structure, URG7.
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