title: Chaperone-like activities of different molecular forms of beta-casein. Importance of polarity of N-terminal hydrophilic domain.
abstract: As a member of intrinsically unstructured protein family, beta-casein (beta-CN) contains relatively high amount of prolyl residues, adopts noncompact and flexible structure and exhibits chaperone-like activity in vitro. Like many chaperones, native beta-CN does not contain cysteinyl residues and exhibits strong tendencies for self-association. The chaperone-like activities of three recombinant beta-CNs wild type (WT) beta-CN, C4 beta-CN (with cysteinyl residue in position 4) and C208 beta-CN (with cysteinyl residue in position 208), expressed and purified from E. coli, which, consequently, lack the phosphorylated residues, were examined and compared with that of native beta-CN using insulin and alcohol dehydrogenase as target/substrate proteins. The dimers (beta-CND) of C4-beta-CN and C208 beta-CN were also studied and their chaperone-like activities were compared with those of their monomeric forms. Lacking phosphorylation, WT beta-CN, C208 beta-CN, C4 beta-CN and C4 beta-CND exhibited significantly lower chaperone-like activities than native beta-CN. Dimerization of C208 beta-CN with two distal hydrophilic domains considerably improved its chaperone-like activity in comparison with its monomeric form. The obtained results demonstrate the significant role played by the polar contributions of phosphorylated residues and N-terminal hydrophilic domain as important functional elements in enhancing the chaperone-like activity of native beta-CN. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 623-632, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.
authors.affiliation: Biopolymères Interactions Assemblages, INRA, équipe Fonctions et Interactions des Protéines Laitières, Nantes Cedex 3, France.
authors.forename: Reza
authors.initials: R
authors.lastname: Yousefi
authors.forename: Yulia Y
authors.initials: YY
authors.lastname: Shchutskaya
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Zimny
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Gaudin
authors.forename: Ali A
authors.initials: AA
authors.lastname: Moosavi-Movahedi
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Muronetz
authors.forename: Yuriy F
authors.initials: YF
authors.lastname: Zuev
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chobert
authors.forename: Thomas
authors.initials: T
authors.lastname: Haertlé