Zeng Y, Middeldorp J, Madjar J J, Ooka T
Laboratoire du Virologie Moléculaire, IVMC, UMR5537, CNRS, Faculté de Médecine R.T.H. Laënnec, Lyon, France.
Virology. 1997 Dec 22;239(2):285-95. doi: 10.1006/viro.1997.8891.
A major 135-kDa DNA binding protein (mDBP) encoded by the BALF2 open reading frame of Epstein-Barr Virus (EBV) is known to be an essential protein for the induction of the lytic cycle. The present investigation was carried out to know whether this protein forms a complex in vivo with other viral DNA binding proteins (DBP) involved in DNA replication: DNA polymerase, EA-D (diffused early antigen), and DNAase. Immunoprecipitation assays followed by mono- and two-dimensional electrophoresis showed that mDBP forms a complex with these three DBP. Other complexes were also found such as EA-D/DNAase, DNA polymerase/DNAase, and DNA polymerase/EA-D. The complexed forms already exist in the early stage of EBV cycle before DNA synthesis is induced in the EBV producer P3HR-1 cell line. The exonuclease activity encoded by DNAase was found to be inhibited when this enzyme complexed with mDBP, while the EBV DNA polymerase retained its activity in the complexed form with mDBP. Our results suggest that these complexes already present before DNA synthesis are necessary for EBV DNA synthesis.
由爱泼斯坦-巴尔病毒（EBV）的BALF2开放阅读框编码的一种主要的135 kDa DNA结合蛋白（mDBP），已知是诱导裂解周期所必需的蛋白。本研究旨在了解该蛋白在体内是否与参与DNA复制的其他病毒DNA结合蛋白（DBP）形成复合物：DNA聚合酶、EA-D（弥散早期抗原）和DNA酶。免疫沉淀试验后进行一维和二维电泳表明，mDBP与这三种DBP形成复合物。还发现了其他复合物，如EA-D/DNA酶、DNA聚合酶/DNA酶和DNA聚合酶/EA-D。在EBV产生细胞系P3HR-1中诱导DNA合成之前，EBV周期早期就已存在复合形式。当DNA酶与mDBP复合时，发现其编码的核酸外切酶活性受到抑制，而EBV DNA聚合酶与mDBP形成复合形式时仍保留其活性。我们的结果表明，这些在DNA合成之前就已存在的复合物对EBV DNA合成是必需的。
