Synthesis of (di)nucleoside polyphosphates by the ubiquitin activating enzyme E1

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• 作者：Maria A. Gü ; nther Sillero ; Anabel de Diego ; Eduardo Silles and Antonio Sillero
• 关键词：Diadenosine pentaphosphate ; (Di)nucleoside polyphosphates ; Ligases ; Proteasome ; Tetrapolyphosphate ; Tripolyphosphate
• 刊名：FEBS Letters
• 出版年：2005
• 出版时间：2005
• 年：2005
• 卷：579
• 期：27
• 页码：6223-6229
• 全文大小：296 K

文摘

Previous work from this laboratory had shown that ligases may catalyze the synthesis of (di)nucleoside polyphosphates. Here, we show that one of the enzymes of the proteasome system (E1 or the ubiquitin (Ub) activating enzyme, EC 6.3.2.19) catalyzes very effectively (k_cat = 0.29 ± 0.05 s⁻¹) the transfer of AMP from the E–AMP–ubiquitin complex to tripolyphosphate or tetrapolyphosphate with formation of adenosine tetra- or pentaphosphate (p₄A or p₅A), respectively. Whereas the concomitant formation of AMP is stimulated by the presence of dithiothreitol in a concentration dependent manner, the synthesis of p₄A is only slightly inhibited by this compound. Previous treatment of the enzyme (E1) with iodoacetamide inhibited only partially the synthesis of p₄A. p₄A can substitute for ATP as substrate of the reaction to generate the ubiquityl adenylate complex. A small amount of diadenosine pentaphosphate (Ap₅A) was also synthesized in the presence of p₄A.