TY - JOUR
T1 - Exploring the cytochrome c folding mechanism
T2 - Cytochrome c552 from Thermus thermophilus folds through an on-pathway intermediate
AU - Travaglini-Allocatelli, Carlo
AU - Gianni, Stefano
AU - Morea, Veronica
AU - Tramontano, Anna
AU - Soulimane, Tewfik
AU - Brunori, Maurizio
PY - 2003/10/17
Y1 - 2003/10/17
N2 - Understanding the role of partially folded intermediate states in the folding mechanism of a protein is a crucial yet very difficult problem. We exploited a kinetic approach to demonstrate that a transient intermediate of a thermostable member of the widely studied cytochrome c family (cytochrome c 552 from Thermus thermophilus) is indeed on-pathway. This is the first clear indication of an obligatory intermediate in the folding mechanism of a cytochrome c. The fluorescence properties of this intermediate demonstrate that the relative position of the heme and of the only tryptophan residue cannot correspond to their native orientation. Based on an analysis of the three-dimensional structure of cytochrome c552, we propose an interpretation of the data which explains the residual fluorescence of the intermediate and is consistent with the established role played by some conserved interhelical interactions in the folding of other members of this family. A limited set of topologically conserved contacts may guide the folding of evolutionary distant cytochromes c through the same partially structured state, which, however, can play different kinetic roles, acting either as an intermediate or a transition state.
AB - Understanding the role of partially folded intermediate states in the folding mechanism of a protein is a crucial yet very difficult problem. We exploited a kinetic approach to demonstrate that a transient intermediate of a thermostable member of the widely studied cytochrome c family (cytochrome c 552 from Thermus thermophilus) is indeed on-pathway. This is the first clear indication of an obligatory intermediate in the folding mechanism of a cytochrome c. The fluorescence properties of this intermediate demonstrate that the relative position of the heme and of the only tryptophan residue cannot correspond to their native orientation. Based on an analysis of the three-dimensional structure of cytochrome c552, we propose an interpretation of the data which explains the residual fluorescence of the intermediate and is consistent with the established role played by some conserved interhelical interactions in the folding of other members of this family. A limited set of topologically conserved contacts may guide the folding of evolutionary distant cytochromes c through the same partially structured state, which, however, can play different kinetic roles, acting either as an intermediate or a transition state.
UR - http://www.scopus.com/inward/record.url?scp=0142135083&partnerID=8YFLogxK
U2 - 10.1074/jbc.M303990200
DO - 10.1074/jbc.M303990200
M3 - Article
C2 - 12842869
AN - SCOPUS:0142135083
SN - 0021-9258
VL - 278
SP - 41136
EP - 41140
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 42
ER -