Steeg C M, Vogt V M
Section of Biochemistry and Molecular and Cellular Biology, Cornell University, Ithaca, New York 14853.
J Virol. 1990 Feb;64(2):847-55. doi: 10.1128/JVI.64.2.847-855.1990.
We have reinvestigated the ability of the matrix protein (MA) (p19gag) of avian sarcoma and leukemia viruses to interact with RNA. Previous reports claimed on the one hand that MA can bind tightly and with a high degree of specificity to avian sarcoma and leukemia virus RNA in vitro and on the other that it cannot bind to RNA at all. We found that MA purified by any of several methods does bind to RNA, as measured by its ability to cause retention of radioactive RNA on nitrocellulose membranes in a filtration assay. However, this interaction is weak and lacks specificity. The interaction of MA with RNA was barely detectable by classical sedimentation analysis, and from this observation we estimate that the intrinsic MA-RNA association constant is ca. 10(3) M-1, at least 3 orders of magnitude smaller than the constant describing the interaction of the viral nucleocapsid protein (NC) (p12gag) with RNA, ca. 10(6) M-1. Separately purified phosphorylated and nonphosphorylated MA species bound RNA equally. We also found that MA can bind to DNA with an affinity similar to that for RNA. The large quantitative discrepancy between our results and earlier published reports can be traced in part to methods of data analysis.
我们重新研究了禽肉瘤和白血病病毒的基质蛋白（MA）（p19gag）与RNA相互作用的能力。此前的报告一方面称，MA在体外能与禽肉瘤和白血病病毒RNA紧密且高度特异性地结合，另一方面又声称它根本不能与RNA结合。我们发现，通过几种方法中的任何一种纯化得到的MA确实能与RNA结合，这可通过在过滤试验中其使放射性RNA保留在硝酸纤维素膜上的能力来衡量。然而，这种相互作用很弱且缺乏特异性。通过经典沉降分析几乎检测不到MA与RNA的相互作用，基于此观察结果我们估计，MA与RNA的内在结合常数约为10³ M⁻¹，至少比描述病毒核衣壳蛋白（NC）（p12gag）与RNA相互作用的常数（约10⁶ M⁻¹）小3个数量级。分别纯化的磷酸化和非磷酸化MA物种与RNA的结合能力相同。我们还发现，MA能以与RNA相似的亲和力结合DNA。我们的结果与早期发表报告之间在数量上的巨大差异部分可归因于数据分析方法。
