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DOI: 10.1055/s-2007-978493
© Georg Thieme Verlag Stuttgart · New York
Identification and Characterization of Activating and Conjugating Enzymes of the Ubiquitin System from the Unicellular Alga Chlamydomonas reinhardtii
Publikationsverlauf
1998
1998
Publikationsdatum:
19. April 2007 (online)

Abstract
Using a biochemical approach we identified families of ubiquitin-activating and ubiquitin-conjugating enzymes in Chlamydomonas reinhardtii. The family of ubiquitin-activating enzymes, characterized by their ability to form thioesters with ubiquitin and eluting off a ubiquitin affinity column by ATP-depletion probably consists of at least four members. Whereas one of these enzymes is active under a broad range of pH values, thioester of the other UBAs with ubiquitin is restricted to pH 7.5. Two ubiquitin-activating enzymes are metabolically phosphorylated which is assumed to be an activity control mechanism. Most of the 7 ubiquitin-conjugating enzymes detected in this study were found to bind rather tightly to an anion exchange column, and eluted off the column at specific salt concentrations. Two of the ubiquitin-conjugating enzymes described here did, however, not bind to this column. These enzymes can, as all other C. reinhardtii ubiquitin-conjugating enzymes, perform thioester formation with ubiquitin regardless of the source (plant/animal) of the ubiquitin-activating enzyme.
Key words
Chlamydomonas - ubiquitin - UBA - UBC - phosphorylation - biochemistry