Glycation of glyceraldehyde-3-phosphate dehydrogenase inhibits the binding with α-synuclein and RNA.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) shows great diversity of functions, interaction partners and post-translational modifications. GAPDH undergoes glycation of positively charged residues in diabetic patient's tissues and therefore may change interaction with partners. The influence of GAPDH glycation on interaction with two important partners, α-synuclein and RNA, has been investigated in silico using molecular dynamics simulations and in vitro using surface plasmon resonance measurements. Since positively charged groove including substrate- and NAD-binding sites is proposed as potential binding site for α-synuclein and RNA, GAPDH was glycated on residues in grooves and randomly distributed over the whole surface. Lysine residues were replaced with negatively charged carboxymethyl lysine as a widespread advanced glycation end product. As results, GAPDH glycation suppressed the interaction with α-synuclein and RNA. Although the modified GAPDH residues participated in binding with α-synuclein, no stable binding site with both glycated forms was observed. Glycation along the whole GAPDH surface completely suppressed interaction with RNA, whereas the alternative possible RNA binding site was identified in case of groove glycation. The findings were supported by direct measurement of the binding affinity. The obtained results clarify effect of glycation on GAPDH interaction with α-synuclein and RNA and elucidate a possible mechanism of interplay between glycation occurred in diabetes and neurodegenerative diseases, which GAPDH and α-synuclein are involved in.