Cohen E A, Gaudreau P, Brazeau P, Langelier Y
Nature. 1986;321(6068):441-3. doi: 10.1038/321441a0.
Ribonucleotide reductase, an essential enzyme for the synthesis of deoxyribonucleotides, is formed by the association of two nonidentical subunits in almost all prokaryotic and eukaryotic cells. The same model probably holds for the herpes simplex virus (HSV)-encoded ribonucleotide reductase; two polypeptides of relative molecular mass 136,000 (136K; H1) and 40K (H2) (referred to elsewhere as RR1 and RR2; see for example, Dutia et al.) have been associated with the viral enzyme by both genetic and immunological studies. Furthermore, DNA sequence analyses have shown significant stretches of amino-acid homology between these viral polypeptides and those of, respectively, subunit 1 (ref. 12) and subunit 2 (ref. 13) of the Escherichia coli and mammalian enzymes. To assess the involvement of the 40K polypeptide in reductase activity, we synthesized a nonapeptide corresponding to the sequence of its carboxy terminus with the intention of raising neutralizing antibodies specific for the viral activity (E.A.C. et al., in preparation). We report here the unexpected finding that the nonapeptide itself specifically inhibits the HSV ribonucleotide reductase activity in a reversible, non-competitive manner, and we suggest that it does this by impairment of the correct association of the two subunits. This phenomenon emphasizes the potential usefulness of synthetic peptides in probing critical sites involved in macromolecular interactions.
核糖核苷酸还原酶是脱氧核糖核苷酸合成所必需的一种酶，在几乎所有原核和真核细胞中，它由两个不同的亚基结合形成。单纯疱疹病毒（HSV）编码的核糖核苷酸还原酶可能也遵循同样的模式；通过遗传学和免疫学研究发现，相对分子质量为136,000（136K；H1）和40K（H2）的两种多肽（在其他地方称为RR1和RR2；例如，见Dutia等人的研究）与该病毒酶相关。此外，DNA序列分析表明，这些病毒多肽与大肠杆菌和哺乳动物酶的亚基1（参考文献12）和亚基2（参考文献13）的氨基酸序列有显著的同源性。为了评估40K多肽在还原酶活性中的作用，我们合成了一种与其羧基末端序列对应的九肽，目的是产生针对病毒活性的中和抗体（E.A.C.等人，正在准备中）。我们在此报告一个意外发现，即该九肽本身以可逆的、非竞争性的方式特异性抑制HSV核糖核苷酸还原酶的活性，我们认为这是通过损害两个亚基的正确结合来实现的。这一现象强调了合成肽在探测参与大分子相互作用的关键位点方面的潜在用途。
