Membrane insertion of αA-crystallin is oligomer-size dependent

Harry Christianto Tjondro, Yi Bo Xi, Xiang Jun Chen, Jing Tan Su, Yong Bin Yan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Vertebrate lens is one of the tissues with the highest soluble protein concentration. The predominant soluble proteins in lens fiber cells are crystallins, and among them, α-crystallins belong to the small heat shock protein family with chaperone-like activity. Although α-crystallins are highly soluble in waters, α-crystallins have been detected in the membrane-bound fraction of lens, which will increase in the aged or cataractous lens. In this research, we found αA-crystallin exhibited a complex thermal transition with remarkable changes in secondary and quaternary structures. Treatment of αA-crystallin at high temperatures induced larger oliogomers with higher hydrophobic exposure. Both heat-treated and untreated αA-crystallin could insert into lipid monolayer directly as revealed by monolayer surface pressure experiments. Heat-treatment facilitated the membrane insertion of αA-crystallin and increased the membrane-bound fraction in the cells. The membrane-binding ability of αA-crystallin could be altered by cataract-causing mutations R116C, R116H and Y118D. Our results suggested that the irreversible changes in oligomer size induced by various stresses might promote the membrane association of αA-crystallin and therefore might play a role in aged cataract. Alternations in the membrane binding ability of α-crystallins might be important to the understanding of both aged and congenital cataracts.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume473
Issue number1
DOIs
Publication statusPublished - 22 Apr 2016
Externally publishedYes

Keywords

  • αA-crystallin
  • oligomerization
  • heat shock
  • membrane binding
  • small heat shock proteins
  • cataract

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