These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Structural and functional consequences of chaperone site deletion in αA-crystallin.
    Author: Santhoshkumar P, Karmakar S, Sharma KK.
    Journal: Biochim Biophys Acta; 2016 Nov; 1864(11):1529-38. PubMed ID: 27524665.
    Abstract:
    The chaperone-like activity of αA-crystallin has an important role in maintaining lens transparency. Previously we identified residues 70-88 as a chaperone site in αA-crystallin. In this study, we deleted the chaperone site residues to generate αAΔ70-76 and αAΔ70-88 mutants and investigated if there are additional substrate-binding sites in αA-crystallin. Both mutant proteins when expressed in E. coli formed inclusion bodies, and on solubilizing and refolding, they exhibited similar structural properties, with a 2- to 3-fold increase in molar mass compared to the molar mass of wild-type protein. The deletion mutants were less stable than the wild-type αA-crystallin. Functionally αAΔ70-88 was completely inactive as a chaperone, while αAΔ70-76 demonstrated a 40-50% reduction in anti-aggregation activity against alcohol dehydrogenase (ADH). Deletion of residues 70-88 abolished the ADH binding sites in αA-crystallin at physiological temperature. At 45°C, cryptic ADH binding site(s) became exposed, which contributed subtly to the chaperone-like activity of αAΔ70-88. Both of the deletion mutants were completely inactive in suppressing aggregation of βL-crystallin at 53°C. The mutants completely lost the anti-apoptotic property that αA-crystallin exhibits while they protected ARPE-19 (a human retinal pigment epithelial cell line) and primary human primary lens epithelial (HLE) cells from oxidative stress. Our studies demonstrate that residues 70-88 in αA-crystallin act as a primary substrate binding site and account for the bulk of the total chaperone activity. The β3 and β4 strands in αA-crystallin comprising 70-88 residues play an important role in maintenance of the structure and in preventing aggregation of denaturing proteins.
    [Abstract] [Full Text] [Related] [New Search]