Cataract-causing mutations L45P and Y46D promote γC-crystallin aggregation by disturbing hydrogen bonds network in the second Greek key motif

Congenital cataracts caused by genetic disorders are the primary cause of child blindness across the globe. In this work, we investigated the underlying molecular mechanism of two mutations, L45P and Y46D of gamma C-crystallin in two Chinese families causing nuclear congenital cataracts. Spectroscopic experiments were performed to determine structural differences between the wild-type (WT) and the L45P or Y46D mutant of gamma C-crystallin, and the structural stabilities of the WT and mutant proteins were measured under environmental stress (ultraviolet irradiation, pH disorders, oxidative stress, or chemical denaturation). The L45P and Y46D mutants had lower protein solubility and more hydrophobic residues exposed, making them prone to aggregation under environmental stress. The dynamic molecular simulation revealed that the L45P and Y46D mutations destabilized gamma C-crystallin by altering the hydrogen bonds network around the Trp residues in the second Greek key motif. In summary, L45P and Y46D mutants of gamma C-crystallin caused more hydrophobic residues to be solvent-exposed, lowered the solubility of gamma C-crystallin, and increased aggregation propensity under environmental stress. These might be the pathogenesis of gamma C-crystallin L45P and Y46D mutants related to congenital cataract. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Congenital cataracts caused by genetic disorders are the primary cause of child blindness across the globe. This study investigated two mutations of gamma C-crystallin in Chinese families with nuclear congenital cataracts, revealing that these mutations destabilized the protein and increased aggregation propensity under environmental stress.