Enhancement of NEIL1 protein-initiated oxidized DNA base excision repair by heterogeneous nuclear ribonucleoprotein U (hnRNP-U) via direct interaction

Muralidhar L. Hegde, Srijita Banerjee, Pavana M. Hegde, Larry J. Bellot, Tapas K. Hazra, Istvan Boldogh, Sankar Mitra

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Repair of oxidized base lesions in the human genome, initiated by DNA glycosylases, occurs via the base excision repair pathway using conserved repair and some non-repair proteins. However, the functions of the latter noncanonical proteins in base excision repair are unclear. Here we elucidated the role of heterogeneous nuclear ribonucleoprotein-U (hnRNP-U), identified in the immunoprecipitate of human NEIL1, a major DNA glycosylase responsible for oxidized base repair. hnRNP-U directly interacts with NEIL1 in vitro via the NEIL1 common interacting C-terminal domain, which is dispensable for its enzymatic activity. Their in-cell association increases after oxidative stress. hnRNP-U stimulates the NEIL1 in vitro base excision activity for 5-hydroxyuracil in duplex, bubble, forked, or single-stranded DNA substrate, primarily by enhancing product release. Using eluates from FLAG-NEIL1 immunoprecipitates from human cells, we observed 3-fold enhancement in complete repair activity after oxidant treatment. The lack of such enhancement in hnRNP-U-depleted cells suggests its involvement in repairing enhanced base damage after oxidative stress. The NEIL1 disordered C-terminal region binds to hnRNP-U at equimolar ratio with high affinity (Kd = ∼54 nM). The interacting regions in hnRNP-U, mapped to both termini, suggest their proximity in the native protein; these are also disordered, based on PONDR (Predictor of Naturally Disordered Regions) prediction and circular dichroism spectra. Finally, depletion of hnRNP-U and NEIL1 epistatically sensitized human cells at low oxidative genome damage, suggesting that the hnRNP-U protection of cells after oxidative stress is largely due to enhancement of NEIL1-mediated repair.

Original languageEnglish (US)
Pages (from-to)34202-34211
Number of pages10
JournalJournal of Biological Chemistry
Issue number41
StatePublished - Oct 5 2012

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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