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TRIM32 RING
Structural highlights
DiseaseTRI32_HUMAN Defects in TRIM32 are the cause of limb-girdle muscular dystrophy type 2H (LGMD2H) [MIM:254110; also known as muscular dystrophy Hutterite type. LGMD2H is an autosomal recessive degenerative myopathy characterized by pelvic girdle, shoulder girdle and quadriceps muscle weakness. Clinical phenotype and severity are highly variable. Disease progression is slow and most patients remain ambulatory into the sixth decade of life.[1] [2] Defects in TRIM32 are the cause of Bardet-Biedl syndrome type 11 (BBS11) [MIM:209900. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, autosomal recessive disorder characterized by usually severe pigmentary retinopathy, early onset obesity, polydactyly, hypogenitalism, renal malformation and mental retardation. Secondary features include diabetes mellitus, hypertension and congenital heart disease. A relatively high incidence of BBS is found in the mixed Arab populations of Kuwait and in Bedouin tribes throughout the Middle East, most likely due to the high rate of consaguinity in these populations and a founder effect.[3] FunctionTRI32_HUMAN Has an E3 ubiquitin ligase activity. Ubiquitinates DTNBP1 (dysbindin) and promotes its degradation. May play a significant role in mediating the biological activity of the HIV-1 Tat protein in vivo. Binds specifically to the activation domain of HIV-1 Tat and can also interact with the HIV-2 and EIAV Tat proteins in vivo.[4] Publication Abstract from PubMedTRIM E3 ubiquitin ligases regulate a wide variety of cellular processes and are particularly important during innate immune signalling events. They are characterized by a conserved tripartite motif in their N-terminal portion which comprises a canonical RING domain, one or two B-box domains and a coiled-coil region that mediates ligase dimerization. Self-association via the coiled-coil has been suggested to be crucial for catalytic activity of TRIMs; however, the precise molecular mechanism underlying this observation remains elusive. Here, we provide a detailed characterization of the TRIM ligases TRIM25 and TRIM32 and show how their oligomeric state is linked to catalytic activity. The crystal structure of a complex between the TRIM25 RING domain and an ubiquitin-loaded E2 identifies the structural and mechanistic features that promote a closed E2~Ub conformation to activate the thioester for ubiquitin transfer allowing us to propose a model for the regulation of activity in the full-length protein. Our data reveal an unexpected diversity in the self-association mechanism of TRIMs that might be crucial for their biological function. Functional role of TRIM E3 ligase oligomerization and regulation of catalytic activity.,Koliopoulos MG, Esposito D, Christodoulou E, Taylor IA, Rittinger K EMBO J. 2016 May 6. pii: e201593741. PMID:27154206[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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