Ubiquitin-like proteins in halobacteria.

Within our studies of protein degradation, the presence of ubiquitinylated proteins in haloalkaliphilic archaea was investigated. We found that Natronococcus occultus proteins that react with antibodies raised against ubiquitin appear in different growth phases, particularly in the initial and exponential ones. The expression of these proteins is increased when the cells are either treated with puromycin or starved for nutrients. Dot blot analysis of cell extracts with antibody against ubiquitin shows the presence of either ubiquitinylated or ubiquitin-like proteins not only in Natronococcus occultus, but also in various genera of halobacteria.