3zgq
From Proteopedia
Crystal structure of human interferon-induced protein IFIT5
Structural highlights
Function[IFIT5_HUMAN] Interferon-induced RNA-binding protein that specifically binds single-stranded RNA bearing a 5'-triphosphate group (PPP-RNA), thereby acting as a sensor of viral single-stranded RNAs. Single-stranded PPP-RNAs, which lack 2'-O-methylation of the 5' cap and bear a 5'-triphosphate group instead, are specific from viruses, providing a molecular signature to distinguish between self and non-self mRNAs by the host during viral infection. Directly binds PPP-RNA in a non-sequence-specific manner. Also recognizes and binds tRNAs.[1] [2] Publication Abstract from PubMedInterferon-induced proteins, including the largely uncharacterized interferon-induced tetratricopeptide repeat (IFIT) protein family, provide defenses against pathogens. Differing from expectations for tetratricopeptide repeat (TPR) proteins and from human IFIT1, IFIT2, and IFIT3, we show that human IFIT5 recognizes cellular RNA instead of protein partners. In vivo and in vitro, IFIT5 bound to endogenous 5'-phosphate-capped RNAs, including transfer RNAs. The crystal structure of IFIT5 revealed a convoluted intramolecular packing of eight TPRs as a fold that we name the TPR eddy. Additional, non-TPR structural elements contribute to an RNA binding cleft. Instead of general cytoplasmic distribution, IFIT5 concentrated in actin-rich protrusions from the apical cell surface colocalized with the RNA-binding retinoic acid-inducible gene-I (RIG-I). These findings establish compartmentalized cellular RNA binding activity as a mechanism for IFIT5 function and reveal the TPR eddy as a scaffold for RNA recognition. tRNA Binding, Structure, and Localization of the Human Interferon-Induced Protein IFIT5.,Katibah GE, Lee HJ, Huizar JP, Vogan JM, Alber T, Collins K Mol Cell. 2013 Feb 21;49(4):743-50. doi: 10.1016/j.molcel.2012.12.015. Epub 2013 , Jan 11. PMID:23317505[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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