title: Functional and structural similarity between the X protein of hepatitis B virus and nucleoside diphosphate kinases.
abstract: One of the four genes encoded by hepatitis B virus (HBV) is the regulatory 17 kDa protein called HBx (or pX). HBx is a transcription transactivator of many cellular and viral regulatory elements. We report here that recombinant HBx supports transcription in vitro and has phosphotransfer enzymatic activity. In the presence of EDTA, a phosphoryl-HBx is formed that releases the phosphate residue upon the addition of Mg2+. This two-step NTP hydrolysis reaction is characteristic of a group of enzymes termed nucleoside diphosphate kinases (NDPKs). Remarkably, structural similarity between HBx and NDPKs is also evident. Our findings suggest that HBx has evolved from this group of enzymes but acquired additional activities that satisfy the viral needs.
authors.affiliation: Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: T
authors.initials: T
authors.lastname: De-Medina
authors.forename: Y
authors.initials: Y
authors.lastname: Shaul
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D006801:Humans; D008969:Molecular Sequence Data; D009701:Nucleoside-Diphosphate Kinase / Q000737:chemistry / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D011994:Recombinant Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D011494:Protein Kinases; D009701:Nucleoside-Diphosphate Kinase