PMID: 25451934
White MR, Khan MM, Deredge D, Ross CR, Quintyn R, Zucconi BE, Wysocki VH, Wintrode PL, Wilson GM, Garcin ED
A Dimer Interface Mutation in Glyceraldehyde 3-Phosphate Dehydrogenase Regulates its Binding to AU-rich RNA.
J Biol Chem. 2014 Dec 1. pii: jbc.M114.618165.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an enzyme best known for its role in glycolysis. However, extra-glycolytic functions of GAPDH have been described, including regulation of protein expression via RNA binding. GAPDH binds to numerous Adenine-Uridine Rich Elements (AREs) from various mRNA 3' untranslated regions (3'UTR) in vitro and in vivo, despite its lack of a canonical RNA binding motif. How GAPDH binds to these AREs is still unknown. Here we discovered that GAPDH binds with high-affinity to the core ARE from Tumor Necrosis Factor-alpha (TNF-alpha) mRNA via a two-step binding mechanism. We demonstrate that a mutation at the GAPDH dimer interface impairs formation of the second RNA:GAPDH complex and leads to changes in the RNA structure. We investigated the effect of this interfacial mutation on GAPDH oligomerization by crystallography, small-angle x-ray scattering, nano-ElectroSpray Ionization Mass Spectrometry and Hydrogen-Deuterium Exchange Mass Spectrometry. We show that the mutation does not significantly affect GAPDH tetramerization as previously proposed. Instead, the mutation promotes short-range and long-range dynamic changes in regions located at the dimer and tetramer interface and in the NAD+ binding site. These dynamic changes are localized along the P axis of the GAPDH tetramer, suggesting that this region is important for RNA binding. Based on our results, we propose a model for sequential GAPDH binding to RNA via residues located at the dimer and tetramer interfaces.