6k5t
Complex of SUMO1 and phosphorylated hcmv protein IE2
Structural highlights
DiseaseSUMO1_HUMAN Defects in SUMO1 are the cause of non-syndromic orofacial cleft type 10 (OFC10) [MIM:613705; also called non-syndromic cleft lip with or without cleft palate 10. OFC10 is a birth defect consisting of cleft lips with or without cleft palate. Cleft lips are associated with cleft palate in two-third of cases. A cleft lip can occur on one or both sides and range in severity from a simple notch in the upper lip to a complete opening in the lip extending into the floor of the nostril and involving the upper gum. Note=A chromosomal aberation involving SUMO1 is the cause of OFC10. Translocation t(2;8)(q33.1;q24.3). The breakpoint occurred in the SUMO1 gene and resulted in haploinsufficiency confirmed by protein assays.[1] FunctionSUMO1_HUMAN Ubiquitin-like protein that can be covalently attached to proteins as a monomer or a lysine-linked polymer. Covalent attachment via an isopeptide bond to its substrates requires prior activation by the E1 complex SAE1-SAE2 and linkage to the E2 enzyme UBE2I, and can be promoted by E3 ligases such as PIAS1-4, RANBP2 or CBX4. This post-translational modification on lysine residues of proteins plays a crucial role in a number of cellular processes such as nuclear transport, DNA replication and repair, mitosis and signal transduction. Involved for instance in targeting RANGAP1 to the nuclear pore complex protein RANBP2. Polymeric SUMO1 chains are also susceptible to polyubiquitination which functions as a signal for proteasomal degradation of modified proteins. May also regulate a network of genes involved in palate development.[2] [3] [4] [5] Publication Abstract from PubMedMany viral factors manipulate the host post-translational modification (PTM) machinery for efficient viral replication. In particular, phosphorylation and SUMOylation can distinctly regulate the activity of the human cytomegalovirus (HCMV) transactivator immediate early 2 (IE2). However, the molecular mechanism of this process is unknown. Using various structural, biochemical, and cell-based approaches, here we uncovered that IE2 exploits a cross-talk between phosphorylation and SUMOylation. A scan for small ubiquitin-like modifier (SUMO)-interacting motifs (SIMs) revealed two SIMs in IE2, and a real-time SUMOylation assay indicated that the N-terminal SIM (IE2-SIM1) enhances IE2 SUMOylation up to 4-fold. Kinetic analysis and structural studies disclosed that IE2 is a SUMO cis-E3 ligase. We also found that two putative casein kinase 2 (CK2) sites adjacent to IE2-SIM1 are phosphorylated in vitro and in cells. The phosphorylation drastically increased IE2-SUMO affinity, IE2 SUMOylation, and cis-E3 activity of IE2. Additional salt bridges between the phosphoserines and SUMO accounted for the increased IE2-SUMO affinity. Phosphorylation also enhanced the SUMO-dependent transactivation activity and auto-repression activity of IE2. Together, our findings highlight a novel mechanism whereby SUMOylation and phosphorylation of the viral cis-E3 ligase and transactivator protein IE2 work in tandem to enable transcriptional regulation of viral gene. Casein kinase-2-mediated phosphorylation increases the SUMO-dependent activity of the cytomegalovirus transactivator IE2.,Tripathi V, Chatterjee KS, Das R J Biol Chem. 2019 Oct 4;294(40):14546-14561. doi: 10.1074/jbc.RA119.009601. Epub , 2019 Aug 1. PMID:31371453[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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