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Proc Natl Acad Sci U S A. 2014 Aug 19;111(33):12025-30. doi: 10.1073/pnas.1412842111. Epub 2014 Aug 4.

Broad and adaptable RNA structure recognition by the human interferon-induced tetratricopeptide repeat protein IFIT5.

Author information

1
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720; and.
2
Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712.
3
Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712 lambowitz@austin.utexas.edu kcollins@berkeley.edu.
4
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720; and lambowitz@austin.utexas.edu kcollins@berkeley.edu.

Abstract

Interferon (IFN) responses play key roles in cellular defense against pathogens. Highly expressed IFN-induced proteins with tetratricopeptide repeats (IFITs) are proposed to function as RNA binding proteins, but the RNA binding and discrimination specificities of IFIT proteins remain unclear. Here we show that human IFIT5 has comparable affinity for RNAs with diverse phosphate-containing 5'-ends, excluding the higher eukaryotic mRNA cap. Systematic mutagenesis revealed that sequence substitutions in IFIT5 can alternatively expand or introduce bias in protein binding to RNAs with 5' monophosphate, triphosphate, cap0 (triphosphate-bridged N7-methylguanosine), or cap1 (cap0 with RNA 2'-O-methylation). We defined the breadth of cellular ligands for IFIT5 by using a thermostable group II intron reverse transcriptase for RNA sequencing. We show that IFIT5 binds precursor and processed tRNAs, as well as other RNA polymerase III transcripts. Our findings establish the RNA recognition specificity of the human innate immune response protein IFIT5.

KEYWORDS:

RNA post-transcriptional modifications; innate immunity; poly-U tailing; protein–RNA interaction; tRNA processing

PMID:
25092312
PMCID:
PMC4143023
DOI:
10.1073/pnas.1412842111
[Indexed for MEDLINE]
Free PMC Article

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