Division of Cancer Development System, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
Toxicon. 2013 Mar 1;63:55-63. doi: 10.1016/j.toxicon.2012.11.019. Epub 2012 Dec 2.
The Streptomyces coelicolor A3(2) genome encodes a possible secretion protein, SCO5461, that shares a 30% homology with the activity domains of two toxic ADP-ribosyltransferases, pierisins and mosquitocidal toxin. We found ADP-ribosylating activity for the SCO5461 protein product through its co-incubation with guanosine and NAD(+), which resulted in the formation of N(2)-(ADP-ribos-1-yl)-guanosine ((ar2)Guo), with a K(m) value of 110 μM. SCO5461 was further found to ADP-ribosylate deoxyguanosine, GMP, dGMP, GTP, dGTP, and cyclic GMP with k(cat) values of 150-370 s(-1). Oligo(dG), oligo(G), and yeast tRNA were also ADP-ribosylated by this protein, although with much lower k(cat) values of 0.2 s(-1) or less. SCO5461 showed maximum ADP-ribosylation activity towards guanosine at 30 °C, and maintained 20% of these maximum activity levels even at 0 °C. This is the first report of the ADP-ribosylation of guanosine and guanine mononucleotides among the family members of various ADP-ribosylating enzymes. We additionally observed secretion of the putative gene product, SCO5461, in liquid cultures of S. coelicolor. We thus designated the SCO5461 protein product as S. coelicolor ADP-ribosylating protein, ScARP. Our current results could offer new insights into not only the ADP-ribosylation of small molecules but also signal transduction events via enzymatic nucleoside modification by toxin-related enzymes.
链霉菌 A3(2) 基因组编码一种可能的分泌蛋白 SCO5461，它与两种毒性 ADP-核糖基转移酶——pierisin 和蚊毒性毒素的活性结构域有 30%的同源性。我们发现 SCO5461 蛋白产物在与鸟苷和 NAD(+)共孵育时具有 ADP-核糖基转移酶活性，导致形成 N(2)-(ADP-核糖基)-鸟苷 ((ar2)Guo)，K(m) 值为 110 μM。进一步发现 SCO5461 可以 ADP-核糖基化脱氧鸟苷、GMP、dGMP、GTP、dGTP 和环鸟苷，k(cat) 值为 150-370 s(-1)。该蛋白还可以 ADP-核糖基化寡脱氧鸟苷、寡鸟苷和酵母 tRNA，但 k(cat) 值要低得多，为 0.2 s(-1)或更低。SCO5461 在 30°C 时对鸟苷的 ADP-核糖基化活性最高，即使在 0°C 时也能保持最大活性的 20%。这是首次报道各种 ADP-核糖基转移酶家族成员对鸟苷和鸟嘌呤核苷酸的 ADP-核糖基化。我们还观察到链霉菌在液体培养中分泌推测的基因产物 SCO5461。因此，我们将 SCO5461 蛋白产物命名为链霉菌 ADP-核糖基转移蛋白 ScARP。我们目前的结果不仅可以为小分子的 ADP-核糖基化提供新的见解，还可以为毒素相关酶通过酶促核苷修饰进行信号转导事件提供新的见解。
