The native oligomeric organization of alpha-crystallin, is it necessary for its chaperone function?
Citraconylation of all the lysine residues of alpha B and alpha A disrupts the native oligomeric state of these proteins. For alpha B, the oligomerization is concentration dependent with monomers and dimers formed at low protein concentration (approximately 0.01 mg ml(-1)). For concentration higher than 0.5 mg ml(-1) tetramers are the major species. Citraconylated alpha A crystallin is mostly tetrameric at any concentration. Citraconylation had a major effect on the secondary structure of alpha B which was reflected by a significant loss of beta-sheet structure. On the other hand, the secondary structure of alpha A crystallin was not significantly effected by this chemical modification. The chaperone properties of both modified proteins were the same as the native proteins when apo alpha-lactalbumin and malate dehydrogenase were used as target proteins. The data suggest that the native oligomeric state of alpha-crystallin may not be essential for its ability to suppress non-specific aggregation.
Horwitz
Joseph
J
Jules Stein Eye Institute, UCLA School of Medicine, 100 Stein Plaza, Rm B-168, Los Angeles, CA 90095-7008, USA. horwitz@jsei.ucla.edu
Huang
Qingling
Q
Ding
Linlin
L
D000818:Animals; D002949:Citraconic Anhydrides; D018832:Molecular Chaperones / Q000737:chemistry*; D008970:Molecular Weight; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship; D038202:alpha-Crystallin A Chain / Q000737:chemistry; D038203:alpha-Crystallin B Chain / Q000737:chemistry; D038201:alpha-Crystallins / Q000737:chemistry*
D002949:Citraconic Anhydrides; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D038202:alpha-Crystallin A Chain; D038203:alpha-Crystallin B Chain; D038201:alpha-Crystallins