Role of the carboxy-termini of tubulin on its chaperone-like activity

Citation
T. Sarkar et al., Role of the carboxy-termini of tubulin on its chaperone-like activity, PROTEINS, 44(3), 2001, pp. 262-269
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
PROTEINS-STRUCTURE FUNCTION AND GENETICS
ISSN journal
0887-3585 → ACNP
Volume
44
Issue
3
Year of publication
2001
Pages
262 - 269
Database
ISI
SICI code
0887-3585(20010815)44:3<262:ROTCOT>2.0.ZU;2-F
Abstract
Mutational analysis and the enzymatic digestion of many chaperones indicate the importance of both hydrophobic and hydrophilic residues for their uniq ue property. Thus, the chaperone activity of alpha -crystallin is lost due to the substitution of hydrophobic residues or upon enzymatic digestion of the negatively charged residues. Tubulin, an eukaryotic cytoskeletal protei n, exhibits chaperone-like activity as demonstrated by prevention of DTT-in duced aggregation of insulin, thermal aggregation of alcohol dehydrogenase, beta gamma -crystallin, and other proteins. We have shown that the tubulin lost its chaperone-like activity upon digestion of its negatively charged C-termini. In this article, the role of the C-terminus of individual subuni ts has been investigated. We observe that the digestion of C-terminus of be ta -subunit with subtilisin causes loss of chaperone-like activity of tubul in. The contribution of C-terminus of alpha -subunit is difficult to establ ish directly as subtilisin cleaves C-terminus of beta -subunit first. This has been ascertained indirectly using a 14-residue peptide P2 having the se quence corresponding to a conserved region of MHC class I molecules and tha t binds tightly to the C-terminus of a-subunit. We have shown that the bind ing of P2 peptide to alpha beta -tubulin causes complete loss of its chaper one-like activity. NAM and gel-electrophoresis studies indicate that the P2 peptide has a significant higher binding affinity for the C-terminus of al pha -subunit compared to that of beta -subunit. Thus, we conclude that both the C-termini are necessary for the chaperone-like activity of tubulin. Im plications for the chaperone functions in vivo have been discussed. (C) 200 1 Wiley-Liss, Inc.