Protein Domain : SidE, PDE domain IPR021014

Type	Domain
Description	This entry represents the phosphodiesterase (PDE) domain from the SidE family of proteins found in the Dot/Icm pathway of Legionella pneumophila bacteria. This domain catalyses the conjugation of ADP-ribosylated ubiquitin (ADPR-Ub), previously synthesised by the mono-ADP-ribosyltransferase (mART) domain, to a serine residue on substrates to generate a protein-phosphoribosyl-Ub (PR-Ub) product [ ]. These pathogen proteins are secreted bacterial effector proteins, which are translocated inside the host cell using the Dot/Icm secretion system [, ]. The SidE family of enzymes carry out ubiquitination of host cell proteins in an E1/E2-independent manner [, ].The SidE family includes four large proteins SidE, SdeA, SdeB, and SdeC, required for efficient intracellular bacterial replication and catalyses ubiquitination in an E1/E2-independent manner. These proteins contain four domains: a DUB domain, a phosphodiesterase (PDE) domain, a mono-ADP-ribosyltransferase (mART) domain, and a coiled-coil (CC) domain [ , ].Ubiquitination is a post-translational modification that regulates many cellular processes, the conventional ubiquitination cascade culminates in a covalent linkage between the C terminus of ubiquitin (Ub) and a target protein [ , ]. SidE family proteins can catalyse the non-canonical ubiquitination of several different substrate proteins, including Rab small GTPases, Reticulon-4 (Rtn4), and Rag small GTPases, as well as SidE proteins themselves []. This specificity resides on the specific ubiquitin-binding surfaces of mART and the unique features of the PDE domain [, ].The DUB activity of SdeA is important for regulating the dynamics of ubiquitin association with the bacterial phagosome, but is not necessary for its role in intracellular bacterial replication [ , ].
Short Name	SidE_PDE