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Functional and structural similarity between the X protein of hepatitis B virus and nucleoside diphosphate kinases
Author(s) -
De-Medina Tali,
Shaul Yosef
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00900-7
Subject(s) - hbx , transactivation , kinase , enzyme , nucleoside , transcription (linguistics) , biochemistry , chemistry , phosphorylation , hepatitis b virus , nucleoside diphosphate kinase , gene , structural similarity , recombinant dna , biology , microbiology and biotechnology , transcription factor , virology , virus , transfection , linguistics , philosophy
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 Mg 2+ . 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.