Chaudhuri B, Hämmerle M, Fürst P
Department of Core Drug Discovery Technologies (CDDT), Ciba-Geigy Ltd., Basel, Switzerland.
FEBS Lett. 1995 Jan 3;357(2):221-6. doi: 10.1016/0014-5793(94)01365-8.
The Ca(2+)-calmodulin dependent protein phosphatase, calcineurin, is thought to mediate the action of the two immunosuppressants, cyclosporin A (CsA) and FK506. Calcineurin from all species consists of a catalytic A subunit and a regulatory peptide B, which plays an essential role in catalysis. The enzymatic function is probably also regulated by an autoinhibitory domain (AID) present in the catalytic subunit. We have used the yeast two-hybrid system to show that the putative AID of the yeast catalytic subunit Cna1 binds only to truncated Cna1, devoid of AID. Although deletion of the genes encoding the yeast catalytic subunits of calcineurin (CNA1 and CNA2) maintain the interaction, absence of the regulatory subunit Cnb1 prevents binding. Interestingly, both CsA and FK506 disrupt this interaction, whereas binding of Cna1 to calmodulin remains unaffected. This indicates that a simple cellular system, developed in yeast, could provide further insight into an understanding of calcineurin inhibition.
钙离子/钙调蛋白依赖性蛋白磷酸酶——钙调神经磷酸酶，被认为介导了两种免疫抑制剂环孢素A（CsA）和FK506的作用。所有物种的钙调神经磷酸酶均由一个催化性A亚基和一个调节肽B组成，调节肽B在催化过程中起关键作用。酶功能可能也受催化亚基中存在的自身抑制结构域（AID）调控。我们利用酵母双杂交系统表明，酵母催化亚基Cna1的假定AID仅与缺失AID的截短型Cna1结合。虽然缺失编码钙调神经磷酸酶酵母催化亚基（CNA1和CNA2）的基因可维持这种相互作用，但缺失调节亚基Cnb1则会阻止结合。有趣的是，CsA和FK506均会破坏这种相互作用，而Cna1与钙调蛋白的结合则不受影响。这表明在酵母中构建的一个简单细胞系统能够为深入理解钙调神经磷酸酶抑制作用提供更多信息。
