Studies on the Potential Autoubiquitination of Dap1 and 25-Dx
Date Issued
2011
Date
2011
Author(s)
Wang, Yu-Peng
Abstract
AtMAPRs in Arabidopsis are homologous to Dap1 in Saccharomyces cerevisiae and 25-Dx in Rattus norvegicus. They are members of MAPR (membrane-associated progesterone receptor) family which characterized by a conserved cytochrome b5 like heme/steroid binding domain. In previous study, it has been demonstrated that the recombinant proteins of AtMAPRs, the MAPR homologs in Arabidopsis thaliana, have E3-independent autoubiquitination activity in vitro. A putative ubiquitin-interacting motif (UIM) was detected in the cytochrome b5 like heme/steroid binding domain of AtMAPRs from a multiple sequence alignment. UIM is a member of UBDs (ubiquitin-binding domains), and the UBD-containing proteins have shown autoubiquitination activity. In this study, recombinant proteins required for the in vitro ubiquitination assay, E2 (UBC4, UBE2D2) and substrate (Dap1, 25-Dx), were produced in E. coli. In vitro ubiquitination assays indicated that Dap1 and 25-Dx did not have autoubiquitination activity. There are some differences in Dap1 and 25-Dx sequences compared with AtMAPR2. This may explain that Dap1 and 25-Dx did not have autoubiquitination activity. These findings suggested that E3-independent autoubiquitination might be an unique character of AtMAPRs in Arabidopsis. Further studies are needed to support this assumption.
Subjects
Dap1
25-Dx
autoubiquitination
MAPR
UBD
Type
thesis
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