Post-translational Modifications of Fumarase Regulate its Enzyme Activity and Function in Respiration and the DNA Damage Response

Suqing Wang, Dharanidharan Ramamurthy, Jasper Tan, Jingyan Liu, Joyce Yip, Andrea Chua, Zhang Yu, Teck Kwang Lim, Qingsong Lin, Ophry Pines*, Norbert Lehming

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The Krebs cycle enzyme fumarase is a dual-targeted protein that is located in the mitochondria and cytoplasm of eukaryotic cells. Besides being involved in the TCA cycle and primary metabolism, fumarase is a tumour suppressor that aids DNA repair in human cells. Using mass spectrometry, we identified modifications in peptides of cytosolic yeast fumarase, some of which were absent when the cells were exposed to DNA damage (using the homing endonuclease system or hydroxyurea). We show that DNA damage increased the enzymatic activity of fumarase, which we hypothesized to be affected by post-translational modifications. Succinylation and ubiquitination of fumarase at lysines 78 and 79, phosphorylation at threonine 122, serine 124 and threonine 126 as well as deamidation at arginine 239 were found to be functionally relevant. Upon homology analysis, these residues were also found to be evolutionally conserved. Serine 128, on the other hand, is not evolutionary conserved and the Fum1S128D phosphorylation mimic was able to aid DNA repair. Our molecular model is that the above modifications inhibit the enzymatic activity of cytosolic fumarase under conditions of no DNA damage induction and when there is less need for the enzyme. Upon genotoxic stress, some fumarase modifications are removed and some enzymes are degraded while unmodified proteins are synthesized. This report is the first to demonstrate how post-translational modifications influence the catalytic and DNA repair functions of fumarase in the cell.

Original languageAmerican English
Pages (from-to)6108-6126
Number of pages19
JournalJournal of Molecular Biology
Volume432
Issue number23
DOIs
StatePublished - 20 Nov 2020

Bibliographical note

Publisher Copyright:
© 2020 The Author(s)

Keywords

  • DNA repair
  • Fumarase
  • TCA cycle
  • enzymatic activity
  • post-translational modification

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