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Synthesis of (di)nucleoside polyphosphates by the ubiquitin activating enzyme E1
Author(s) -
Günther Sillero Maria A.,
de Diego Anabel,
Silles Eduardo,
Sillero Antonio
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.10.003
Subject(s) - iodoacetamide , dithiothreitol , chemistry , enzyme , ubiquitin , nucleoside , biochemistry , substrate (aquarium) , adenylate kinase , adenosine , stereochemistry , cysteine , biology , ecology , gene
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 (p 4 A or p 5 A), respectively. Whereas the concomitant formation of AMP is stimulated by the presence of dithiothreitol in a concentration dependent manner, the synthesis of p 4 A is only slightly inhibited by this compound. Previous treatment of the enzyme (E1) with iodoacetamide inhibited only partially the synthesis of p 4 A. p 4 A can substitute for ATP as substrate of the reaction to generate the ubiquityl adenylate complex. A small amount of diadenosine pentaphosphate (Ap 5 A) was also synthesized in the presence of p 4 A.