title: Regulation of Human Endonuclease V Activity and Relocalization to Cytoplasmic Stress Granules.
abstract: 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.
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.
authors: Meh Sameen
authors: MS
authors: Nawaz
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.
authors: Erik Sebastian
authors: ES
authors: Vik
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.
authors: Natalia
authors: N
authors: Berges
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.
authors: Cathrine
authors: C
authors: Fladeby
authors: 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.
authors: Magnar
authors: M
authors: Bjørås
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.|the Department of Medical Biochemistry, Institute for Clinical Medicine, University of Oslo, NO-0424 Oslo, Norway.
authors: Bjørn
authors: B
authors: Dalhus
authors: From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo, ingrun.alseth@rr-research.no.
authors: Ingrun
authors: I
authors: Alseth
mesh_terms: D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism*; D018053:Arsenites / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000235:genetics; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D039122:Poly(A)-Binding Protein I / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D012313:RNA / Q000235:genetics / Q000378:metabolism*
chemical_list: D018053:Arsenites; D039122:Poly(A)-Binding Protein I; D012313:RNA; D000255:Adenosine Triphosphate; D043224:Deoxyribonuclease (Pyrimidine Dimer); C015001:arsenite
keywords: ATP; PABPC1; RNA; RNA processing; deamination; endonuclease V; inosine; nitrosative stress; ribonuclease; stress granule