Green L M, Berg J M
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218.
Proc Natl Acad Sci U S A. 1990 Aug;87(16):6403-7. doi: 10.1073/pnas.87.16.6403.
Retroviral nucleocapsid proteins contain one or two proposed metal-binding sequences of the form Cys-Xaa2-Cys-Xaa4-His-Xaa4-Cys. Previously, we reported that an 18-amino acid peptide derived from the nucleocapsid protein of Rauscher murine leukemia virus (RMLV) binds metals such as Co2+ and Zn2+. We have now synthesized the entire nucleocapsid protein from RMLV. We report here that the protein also binds Co2+ and Zn2+ and does so with a higher affinity than does the peptide. Limited proteolysis and circular dichroism studies reveal that metal binding induces folding of the metal-binding domain and, perhaps, the regions adjacent to it but the remainder of the protein remains in a relatively unstructured state. In addition, we have synthesized sequence variants of the metal-binding domain that correspond to viral mutations reported in the literature. In many cases, the metal-binding properties of these peptides correlate with the observed biological activity, providing further evidence for the importance of metal binding to nucleocapsid function.
逆转录病毒核衣壳蛋白含有一个或两个呈Cys-Xaa2-Cys-Xaa4-His-Xaa4-Cys形式的推测金属结合序列。此前，我们报道了一种源自劳氏肉瘤病毒（RMLV）核衣壳蛋白的18个氨基酸的肽能结合Co2+和Zn2+等金属。我们现已合成了RMLV的完整核衣壳蛋白。我们在此报告，该蛋白也能结合Co2+和Zn2+，且亲和力比该肽更高。有限蛋白酶解和圆二色性研究表明，金属结合诱导金属结合结构域以及可能与其相邻区域发生折叠，但蛋白的其余部分仍处于相对无结构的状态。此外，我们合成了与文献中报道的病毒突变相对应的金属结合结构域的序列变体。在许多情况下，这些肽的金属结合特性与观察到的生物学活性相关，为金属结合对核衣壳功能的重要性提供了进一步证据。
