Wu J Y, Zhou Z Y, Judd A, Cartwright C A, Robinson W S
Department of Medicine, Stanford University School of Medicine, California 94305.
Cell. 1990 Nov 16;63(4):687-95. doi: 10.1016/0092-8674(90)90135-2.
To study the functional mechanism of the hepatitis B virus (HBV) X (hbx) gene product, we have expressed the hbx protein in E. coli and purified it by HPLC. The purified hbx protein was shown to be active in transactivating transcription directed by the LTR sequence of HIV-1. The hbx protein was found to have an intrinsic serine/threonine protein kinase activity. The hbx protein was detected in hepatitis B virions, and tryptic phosphopeptide maps of the hbx protein phosphorylated in the virion and of the in vitro phosphorylated bacterially expressed hbx protein were similar. Inactivation of the hbx protein by heat, protein-denaturing agents, or an ATP affinity analog, p-fluorosulfonylbenzoyl 5'-adenosine, resulted in loss of both protein kinase activity and trans-activation activity. These results suggest that the HBV-encoded trans-activator hbx is a novel protein kinase.
为研究乙型肝炎病毒（HBV）X（hbx）基因产物的功能机制，我们已在大肠杆菌中表达了hbx蛋白，并通过高效液相色谱法对其进行了纯化。结果表明，纯化后的hbx蛋白对HIV-1长末端重复序列（LTR）介导的转录具有反式激活活性。发现hbx蛋白具有内在的丝氨酸/苏氨酸蛋白激酶活性。在乙型肝炎病毒颗粒中检测到了hbx蛋白，并且病毒颗粒中磷酸化的hbx蛋白与体外磷酸化的细菌表达hbx蛋白的胰蛋白酶磷酸肽图谱相似。通过加热、蛋白质变性剂或ATP亲和类似物对氟磺酰苯甲酰5'-腺苷使hbx蛋白失活，导致蛋白激酶活性和反式激活活性均丧失。这些结果表明，HBV编码的反式激活因子hbx是一种新型蛋白激酶。
