Gomès E, Gordon-Weeks R, Simon-Plas F, Pugin A, Milat M L, Leigh R A, Blein J P
Laboratoire de Phytopharmacie, UA 692 INRA/Université de Bourgogne, Dijon, France.
Biochim Biophys Acta. 1996 Nov 13;1285(1):38-46. doi: 10.1016/s0005-2736(96)00144-7.
Beticolin-1 and beticolin-2, yellow toxins produced by the phytopathogenic fungus Cercospora beticola, inhibit the plasma membrane H(+)-ATPase. Firstly, since beticolins are able to form complexes with Mg2+, the role of the beticolin/Mg2+ complexes in the inhibition of the plasma membrane proton pump has been investigated. Calculations indicate that beticolins could exist under several forms, in the H(+)-ATPase assay mixture, both free or complexed with Mg2+. However, the percentage inhibition of the H(+)-ATPase activity is correlated to the concentration of one single form of beticolin, the dimeric neutral complex Mg2H2B2, which appears to be the active form involved in the H(+)-ATPase inhibition. Secondly, since previous data suggested that beticolins could also be active against other Mg2(+)-dependent enzymes, we tested beticolin-1 on the vacuolar H(+)-PPase, which requires Mg2+ as co-substrate, and on the alkaline and acid phosphatases, which do not use Mg2+ as co-substrate. Only vacuolar H(+)-PPase is sensitive to beticolin-1, which suggests that beticolins are specific to enzymes that use a complex of Mg2+ as the substrate. The same Mg2H2B2 complex which is responsible of the plasma membrane H(+)-ATPase inhibition appears to be also involved in the inhibition of the vacuolar H(+)-PPase.
甜菜生尾孢菌产生的黄色毒素Beticolin-1和Beticolin-2可抑制质膜H(+)-ATP酶。首先，由于Beticolin能够与Mg2+形成复合物，因此对Beticolin/Mg2+复合物在抑制质膜质子泵中的作用进行了研究。计算表明，在H(+)-ATP酶分析混合物中，Beticolin可以以多种形式存在，既可以是游离的，也可以与Mg2+结合。然而，H(+)-ATP酶活性的抑制百分比与一种单一形式的Beticolin（二聚体中性复合物Mg2H2B2）的浓度相关，该复合物似乎是参与H(+)-ATP酶抑制的活性形式。其次，由于先前的数据表明Beticolin也可能对其他Mg2(+)-依赖性酶有活性，我们测试了Beticolin-1对液泡H(+)-焦磷酸酶（需要Mg2+作为共底物）以及碱性和酸性磷酸酶（不使用Mg2+作为共底物）的作用。只有液泡H(+)-焦磷酸酶对Beticolin-1敏感，这表明Beticolin对使用Mg2+复合物作为底物的酶具有特异性。负责抑制质膜H(+)-ATP酶的相同Mg2H2B2复合物似乎也参与了液泡H(+)-焦磷酸酶的抑制。
