THE NOVEL ROLES OF ATP IN ANTAGONIZING THE CROWDING-INDUCED DESTABILIZATION OF HUMAN ΓS-CRYSTALLINS AND IN THE INTERACTION WITH SYNCRIP ACD

Abstract

To fill the knowledge gap of the mechanism about how ATP regulates crystallin proteins, we characterized the binding interaction, solution conformation and thermal stability of WT and four mutants of human γS-crystallins with or without the presence of ATP by NMR, DSF and DLS. Our results show that: (1) ATP indeed antagonizes the crowding-induced destabilization, most likely by mediating the hydration shell; (2) the G18V completely eliminates the antagonizing effect of ATP; (3) ATP antagonizes the crowding-induced destabilizations of the mutants in different ways.

In order to explore that whether ATP can bind the nucleic acid binding proteins/domains without the conserved RRM fold, we depicted the interaction between ATP and SYNCRIP acidic domain (AcD) which is composed of five tandem helixes. Our study proves that ATP does interact with SYNCRIP AcD under physiological conditions, thus suggesting that ATP might bind most, if not all of the nucleic acid binding domains.