Succinylation Is a Gain-of-Function Modification in Human Lens alpha B-Crystallin

Nandi, Sandip K.; Rakete, Stefan ; Nahomi, Rooban B.; Michel, Cole; Dunbar, Alexandra; Fritz, Kristofer S. und Nagaraj, Ram H. (2019): Succinylation Is a Gain-of-Function Modification in Human Lens alpha B-Crystallin. In: Biochemistry, Bd. 58, Nr. 9: S. 1260-1274

Abstract

Acylation of lysine residues is a common post-translational modification of cellular proteins. Here, we show that lysine succinylation, a type of acylation, occurs in human lens proteins. All of the major crystallins exhibited N-epsilon-succinyllysine (SuccK) residues. Quantification of SuccK in human lens proteins (from donors between the ages of 20 and 73 years) by LC-MS/MS showed a range between 1.2 and 14.3 pmol/mg lens protein. The total SuccK levels were slightly reduced in aged lenses (age > 60 years) relative to young lenses (age < 30 years). Immunohistochemical analyses revealed that SuccK was present in epithelium and fiber cells. Western blotting and immunoprecipitation experiments revealed that SuccK is particularly prominent in alpha B-crystallin, and succinylation in vitro revealed that alpha B-crystallin is more prone to succinylation than alpha A-crystallin. Mass spectrometric analyses showed succinylation at K72, K90, K92, K166, K175, and potentially K174 in human lens alpha B-crystallin. We detected succinylation at K72, K82, K90, K92, K103, K121, K150, K166, K175, and potentially K174 by mass spectrometry in mildly succinylated alpha B-crystallin. Mild succinylation improved the chaperone activity of alpha B-crystallin along with minor perturbation in tertiary and quaternary structure of the protein. These observations imply that succinylation is beneficial to alpha B-crystallin by improving its chaperone activity with only mild conformational alterations.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0006-2960
• Sprache: Englisch