4z31
Crystal structure of the RC3H2 ROQ domain in complex with stem-loop and double-stranded forms of RNA
Structural highlights
FunctionRC3H2_HUMAN Post-transcriptional repressor of mRNAs containing a conserved stem loop motif, called constitutive decay element (CDE), which is often located in the 3'-UTR, as in HMGXB3, ICOS, IER3, NFKBID, NFKBIZ, PPP1R10, TNF and in many more mRNAs (By similarity). Binds to CDE and promotes mRNA deadenylation and degradation. This process does not involve miRNAs (By similarity). In follicular helper T (Tfh) cells, represses of ICOS and TNFRSF4 expression, thus preventing spontaneous Tfh cell differentiation, germinal center B-cell differentiation in the absence of immunization and autoimmunity (By similarity). In resting or LPS-stimulated macrophages, controls inflammation by suppressing TNF expression (By similarity). Also recognizes CDE in its own mRNA and in that of paralogous RC3H2, possibly leading to feedback loop regulation (By similarity). Publication Abstract from PubMedRoquins are a family of highly conserved RNA-binding proteins that also contain a RING-type E3 ubiquitin ligase domain. They repress constitutive decay elements containing mRNAs and play a critical role in RNA homeostasis and immunological self-tolerance. Here we present the crystal structures of the RNA-binding region of Roquin paralog RC3H2 in both apo- and RNA-bound forms. The RNA-binding region has a bipartite architecture composed of ROQ and HEPN domains, and can bind to stem-loop and double-stranded RNAs simultaneously. The two domains undergo a large orientation change to accommodate RNA duplex binding. We profiled E2 ubiquitin-conjugating enzymes that pair with Roquins and found that RC3H1 and RC3H2 interact with two sets of overlapping but not identical E2 enzymes to drive the assembly of polyubiquitin chains of different linkages. Crystal structures, small-angle X-ray scattering, and E2 profiling revealed that while the two paralogs are highly homologous, RC3H2 and RC3H1 are different in their structures and functions. We also demonstrated that RNA duplex binding to RC3H2 cross-talks with its E3 ubiquitin ligase function using an in vitro auto-ubiquitination assay. New Insights into the RNA-Binding and E3 Ubiquitin Ligase Activities of Roquins.,Zhang Q, Fan L, Hou F, Dong A, Wang YX, Tong Y Sci Rep. 2015 Oct 22;5:15660. doi: 10.1038/srep15660. PMID:26489670[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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