| Autor: |
Song L; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., Xie Y; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technologygrid.48166.3d, Beijing, China., Li C; Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA., Wang L; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., He C; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., Zhang Y; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., Yuan J; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., Luo J; Department of Respiratory Medicine, Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China., Liu X; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technologygrid.48166.3d, Beijing, China., Xiu Y; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technologygrid.48166.3d, Beijing, China., Li H; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technologygrid.48166.3d, Beijing, China., Gritsenko M; Biological Science Division, Pacific Northwest National Laboratorygrid.451303.0, Richland, Washington, USA., Nakayasu ES; Biological Science Division, Pacific Northwest National Laboratorygrid.451303.0, Richland, Washington, USA., Feng Y; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technologygrid.48166.3d, Beijing, China., Luo ZQ; Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA. |
| Abstrakt: |
Legionella pneumophila promotes its survival and replication in phagocytes by actively modulating cellular processes using effectors injected into host cells by its Dot/Icm type IV secretion system. Many of these effectors function to manipulate the ubiquitin network of infected cells, thus contributing to the biogenesis of the Legionella -containing vacuole (LCV), which is permissive for bacterial replication. Among these, members of the SidE effector family (SidEs) catalyze ubiquitination of functionally diverse host proteins by a mechanism that is chemically distinct from the canonical three-enzyme cascade. The activity of SidEs is regulated by two mechanisms: reversal of the phosphoribosyl ubiquitination by DupA and DupB and direct inactivation by SidJ, which is a calmodulin-dependent glutamylase. In many L. pneumophila strains, SidJ belongs to a two-member protein family. Its homolog SdjA appears to function differently from SidJ despite the high-level similarity in their primary sequences. Here, we found that SdjA is a bifunctional enzyme that exhibits distinct activities toward members of the SidE family. It inhibits the activity of SdeB and SdeC by glutamylation. Unexpectedly, it also functions as a deglutamylase that reverses SidJ-induced glutamylation on SdeA. Our results reveal that an enzyme can catalyze two completely opposite biochemical reactions, which highlights the distinct regulation of phosphoribosyl ubiquitination by the SidJ effector family. IMPORTANCE One unique feature of L. pneumophila Dot/Icm effectors is the existence of protein families with members of high-level similarity. Whereas members of some families are functionally redundant, as suggested by their primary sequences, the relationship between SidJ and SdjA, the two members of the SidJ family, has remained mysterious. Despite their sharing 57% identity, sdjA cannot complement the defects in virulence displayed by a mutant lacking sidJ . SidJ inhibits the activity of the SidE family by a calmodulin (CaM)-dependent glutamylase activity. Here, we found that SdjA is a dual function protein: it is a CaM-dependent glutamylase against SdeB and SdeC but exhibits deglutamylase activity toward SdeA that has been modified by SidJ, indicating that SdjA functions to fine-tune the activity of SidEs. These findings have paved the way for future structural and functional analysis of SdjA, which may reveal novel mechanism for isopeptide bond cleavage and provide insights into the study of protein evolution. |
