Avidan Orna, Bochner Ron, Hizi Amnon
Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 69978, Israel.
Virology. 2006 Jul 20;351(1):42-57. doi: 10.1016/j.virol.2006.03.012. Epub 2006 May 2.
Bovine immunodeficiency virus (BIV) is a lentivirus with no proven pathogenesis in infected cattle. Yet, in experimentally infected rabbits, it causes an AIDS-like disease. Consequently, we expressed two recombinant isoforms of BIV reverse transcriptase (RT), which differ in their C-termini, and studied their catalytic properties. Both isoforms prefer Mg(+2) over Mn(+2) with most DNA polymerase and ribonuclease-H substrates. The processivity of DNA synthesis by the BIV RTs is higher than that of HIV-1 RT, whereas the fidelity of synthesis is even lower than that of the HIV-1 enzyme. The ribonuclease-H cleavage pattern suggests that the spatial distance between the polymerase and ribonuclease-H active sites of the two BIV RT isoforms equals 20 nt, unlike the 17 nt distance observed in almost all other RTs. The longer BIV RT version is somewhat less active than the shorter version, suggesting that the extra 74 residues (with homology to dUTPases) might obstruct efficient catalysis.
牛免疫缺陷病毒（BIV）是一种慢病毒，在感染的牛中尚未证实其发病机制。然而，在实验感染的兔子中，它会引发类似艾滋病的疾病。因此，我们表达了两种BIV逆转录酶（RT）的重组异构体，它们的C末端不同，并研究了它们的催化特性。对于大多数DNA聚合酶和核糖核酸酶H底物，两种异构体都更倾向于Mg(+2)而非Mn(+2)。BIV RTs进行DNA合成的持续合成能力高于HIV-1 RT，而合成的保真度甚至低于HIV-1酶。核糖核酸酶H的切割模式表明，两种BIV RT异构体的聚合酶和核糖核酸酶H活性位点之间的空间距离为20个核苷酸，这与几乎所有其他RT中观察到的17个核苷酸的距离不同。较长版本的BIV RT活性略低于较短版本，这表明额外的74个残基（与dUTPases具有同源性）可能会阻碍高效催化。
