Acetylation of αA-crystallin in the human lens: Effects on structure and chaperone function

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1822

Article

Nagaraj, Ram H.¹  Nahomi, Rooban B.¹  Shanthakumar, Shilpa¹  Linetsky, Mikhail¹  Padmanabha, Smitha¹  Pasupuleti, Nagarekha¹  Wang, Benlian²  Santhoshkumar, Puttur³  Panda, Alok Kumar⁴  Biswas, Ashis⁴ 

[1] Case Western Reserve Univ, Sch Med, Dept Ophthalmol & Visual Sci, Cleveland, OH 44106 USA

[2] Case Western Reserve Univ, Sch Med, Ctr Prote & Mass Spectrometry, Cleveland, OH 44106 USA

[3] Univ Missouri, Dept Ophthalmol, Columbia, MO 65212 USA

[4] Indian Inst Technol, Sch Basic Sci, Bhubaneswar 751013, Orissa, India

关键词: Lysine;    Acetylation;    alpha-Crystallin;    Chaperone;    Human lens;    Aging;   

DOI  :  10.1016/j.bbadis.2011.11.011

来源: Elsevier

【 摘 要 】

alpha-Crystallin is a major protein in the human lens that is perceived to help to maintain the transparency of the lens through its chaperone function. In this study, we demonstrate that many lens proteins including alpha A-crystallin are acetylated in vivo. We found that K70 and K99 in alpha A-crystallin and, K92 and K166 in alpha B-crystallin are acetylated in the human lens. To determine the effect of acetylation on the chaperone function and structural changes, alpha A-crystallin was acetylated using acetic anhydride. The resulting protein showed strong immunoreactivity against a N-epsilon-acetyllysine antibody, which was directly related to the degree of acetylation. When compared to the unmodified protein, the chaperone function of the in vitro acetylated alpha A-crystallin was higher against three of the four different client proteins tested. Because a lysine (residue 70; K70) in alpha A-crystallin is acetylated in vivo, we generated a protein with an acetylation mimic, replacing Lys70 with glutamine (K70Q). The K70Q mutant protein showed increased chaperone function against three client proteins compared to the Wt protein but decreased chaperone function against gamma-crystallin. The acetylated protein displayed higher surface hydrophobicity and tryptophan fluorescence, had altered secondary and tertiary structures and displayed decreased thermodynamic stability. Together, our data suggest that acetylation of alpha A-crystallin occurs in the human lens and that it affects the chaperone function of the protein. (C) 2011 Elsevier B.V. All rights reserved.

【 授权许可】

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