RHODANESE FOLDING IS CONTROLLED BY THE PARTITIONING OF ITS FOLDING INTERMEDIATES

Citation
Bm. Gorovits et al., RHODANESE FOLDING IS CONTROLLED BY THE PARTITIONING OF ITS FOLDING INTERMEDIATES, Biochimica et biophysica acta. Protein structure and molecular enzymology, 1382(1), 1998, pp. 120-128
Citations number
20
Categorie Soggetti
Biology,Biophysics
ISSN journal
01674838
Volume
1382
Issue
1
Year of publication
1998
Pages
120 - 128
Database
ISI
SICI code
0167-4838(1998)1382:1<120:RFICBT>2.0.ZU;2-6
Abstract
Rhodanese is used widely as a model for protein folding, since the enz yme as usually studied refolds poorly unless the process is assisted. Here, the influence of the partitioning of the folding intermediates o f bovine rhodanese on the efficiency of its refolding has been investi gated. Metastable intermediates can be formed during unfolding of the enzyme. The stabilities of these intermediates and the native protein with respect to chemical unfolding can be greatly increased by high co ncentrations of glycerol. The concentration dependence of the protein folding kinetics indicates that associative processes occur during ren aturation. It is suggested that, during enzyme refolding, rhodanese un dergoes fast collapse to an intermediate state I' which partitions to at least two other states (I '' and I'''). One of these states (I''') is able to refold to the native enzyme, while the other state (I '') i s in equilibrium with I' and is prone to slow irreversible aggregation Stabilization of I '' against irreversible aggregation by glycerol re sults in increased yield of the protein refolding and a complex temper ature dependence of the protein renaturation. The nature of the I '' t ype intermediate has been investigated. Based on the fact that extensi ve hydrophobic surfaces are exposed during formation of the intermedia tes, it is suggested that partial dissociation of the two structural d omains of rhodanese is an early event in unfolding. Interactions of di fferent folding intermediates of rhodanese with the chaperonin GroEL w ere investigated, and the results suggest that the more extensively un folded intermediates bind tighter than those that appear later on the rhodanese refolding pathway. (C) 1998 Elsevier Science B.V.