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J Biol Chem. 2016 Oct 7;291(41):21786-21801. Epub 2016 Aug 29.

Regulation of Human Endonuclease V Activity and Relocalization to Cytoplasmic Stress Granules.

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From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.
the Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, and.
the Department of Medical Biochemistry, Institute for Clinical Medicine, University of Oslo, NO-0424 Oslo, Norway.
From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo,


Endonuclease V (EndoV) is an enzyme with specificity for inosines in nucleic acids. Whereas the bacterial homologs are active on both DNA and RNA, the mammalian variants only cleave RNA, at least when assayed with recombinant proteins. Here we show that ectopically expressed, as well as endogenously expressed human (h)EndoV, share the same enzymatic properties as the recombinant protein and cleaves RNA with inosine but not DNA. In search for proteins interacting with hEndoV, polyadenylate-binding protein C1 (PABPC1) was identified. The association between PABPC1 and hEndoV is RNA dependent and furthermore, PABPC1 stimulates hEndoV activity and affinity for inosine-containing RNA. Upon cellular stress, PABPC1 relocates to cytoplasmic stress granules that are multimolecular aggregates of stalled translation initiation complexes formed to aid cell recovery. Arsenite, as well as other agents, triggered relocalization also of hEndoV to cytoplasmic stress granules. As inosines in RNA are highly abundant, hEndoV activity is likely regulated in cells to avoid aberrant cleavage of inosine-containing transcripts. Indeed, we find that hEndoV cleavage is inhibited by normal intracellular ATP concentrations. The ATP stores inside a cell do not overlay stress granules and we suggest that hEndoV is redistributed to stress granules as a strategy to create a local environment low in ATP to permit hEndoV activity.


ATP; PABPC1; RNA; RNA processing; deamination; endonuclease V; inosine; nitrosative stress; ribonuclease; stress granule

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