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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Expression and spectroscopic analysis of a mutant hepatitis B virus onco-protein HBx without cysteine residues

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Rui, Edmilson ; Moura, Patricia Ribeiro de [2] ; Gonçalves, Kaliandra de Almeida ; Kobarg, Jörg
Total Authors: 4
Document type: Journal article
Source: Journal of Virological Methods; v. 126, n. 1/2, p. 65-74, June 2005.
Field of knowledge: Biological Sciences - Biochemistry

Chronic infection of the hepatitis B virus (HBV) is one of the causes leading to liver cancer. The 3.2 kb genome of HBV encodes four proteins: core antigen, surface antigen, a DNA polymerase and the X protein (HBx). The biological functions of HBx are not fully understood. It has been shown that HBx is a potent trans-activator, which activates transcription of many cellular and viral promoters indirectly via protein-protein interactions. These transactivating activities of HBx may contribute to the development of hepatocellular carcinoma. In this paper a truncated mini-HBx(-Cys) (18-142) protein, where the cysteines had been either deleted or substituted by serines, was constructed by site-directed mutagenesis and overexpressed as a 6xHis fusion protein in Escherichia coli. The 6xHis-mini-HBx(-Cys) protein was isolated from inclusion bodies, purified by Ni-affinity chromatography under denaturing conditions and refolded by sequential dialysis. The structure of the 6xHis-mini-HBx(-Cys) protein was analyzed by circular dichroism, fluorescence and one-dimensional NMR spectroscopic assays. The data presented here suggest that HBx is unstructured but has a propensity to gain secondary structure under specific experimental conditions. Its conformational flexibility might partially explain its functional complexity, namely its capacity to interact with a wide array of signaling proteins, transcriptional regulators and nucleic acids. (AU)

FAPESP's process: 98/05891-9 - Expression, purification and crystallization of the hepatitis b virus protein HBX for its structural analysis by X-ray diffraction
Grantee:Jörg Kobarg
Support type: Research Grants - Young Investigators Grants