Panet A, Baltimore D
J Virol. 1987 May;61(5):1756-60. doi: 10.1128/JVI.61.5.1756-1760.1987.
To study Moloney murine leukemia virus (M-MulV) proteins associated with the integration of proviral DNA into the host chromosome, we isolated endonuclease activities from purified virion preparations of the wild type and two of its replication mutants. A major endonuclease activity was identified in virions of M-MuLV; the enzyme catalyzed nicks in double-stranded DNA in the presence of either Mn2+ or Mg2+ and was stimulated by ATP. The endonuclease nicked DNA adjacent to all four nucleotides with some preference for G and C. The same enzyme, and in comparable amounts, was isolated from two virus replication mutants: dl2905, deficient in the processing of Pr65gag and Pr200gag-pol, and dl50401, deficient for the virus integration function. In the process of these experiments, the residual reverse transcriptase in mutant dl2905 was shown to be the mature size, implying that the uncleaved precursor lacks enzymatic activity. It appears that the major endonuclease activity found in virions of M-MuLV is not encoded by either the gag or pol genes.
为了研究与前病毒DNA整合到宿主染色体相关的莫洛尼鼠白血病病毒（M-MuLV）蛋白，我们从野生型及其两个复制突变体的纯化病毒粒子制剂中分离出核酸内切酶活性。在M-MuLV的病毒粒子中鉴定出一种主要的核酸内切酶活性；该酶在Mn2+或Mg2+存在的情况下催化双链DNA中的切口，并受到ATP的刺激。核酸内切酶在与所有四种核苷酸相邻的位置切割DNA，对G和C有一定偏好。从两个病毒复制突变体中分离出了相同的酶，且数量相当：dl2905，在Pr65gag和Pr200gag-pol的加工方面存在缺陷；dl50401，在病毒整合功能方面存在缺陷。在这些实验过程中，突变体dl2905中残留的逆转录酶显示为成熟大小，这意味着未切割的前体缺乏酶活性。看来在M-MuLV病毒粒子中发现的主要核酸内切酶活性不是由gag或pol基因编码的。
