Essential regions of deubiquitinating enzyme activity and enhancer function for DUB-2A expressed in T-lymphocytes.

Novel subfamily members of deubiquitinating enzyme gene, DUB-1 and DUB-2, are known to be immediate-early genes and are specifically expressed in B-lymphocytes and T-lymphocytes, respectively. Recently, another deubiquitinating enzyme gene DUB-2A, expressed also in T-lymphocytes, has been isolated and we, in this study, found that Dub-2A has isopeptidase activity and there are at least 4 conserved amino acids (Cys60, Asp133, His298, and His307) that are required for catalytic activity of the enzyme. Interestingly, the conserved Asp323 was not essential for the catalytic activity. In addition, transcriptional reporter assay showed that an Ets site and 2 AP-1 sites in the enhancer domain of this gene are required for cytokine inducibility. Taken all together, these results will be very helpful in designing activators or inhibitors of this enzyme in order to regulate its expression and catalytic activity in T-lymphocytes.