INVESTIGADORES
DELFINO Jose Maria
artículos
Título:
Consolidation of the Thioredoxin Fold by Peptide Recognition: Interaction between E. coli Thioredoxin Fragments 1-93 and 94-108
Autor/es:
SANTOS J; MARINO-BUSLJE C; KLEINMAN C; ERMACORA MR; DELFINO JM
Revista:
BIOCHEMISTRY
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2007 vol. 46 p. 5148 - 5159
ISSN:
0006-2960
Resumen:
Escherichia coli thioredoxin (TRX) catalyzes redox reactions via the reversible oxidation of
the conserved active center WCGPC. TRX is a monomeric R/â protein with a fold characterized by a
central â-sheet surrounded by R-helical elements. The interaction of the C-terminal R-helix (helix 5) of
TRX against the remainder of the protein involves the close packing of hydrophobic surfaces, opening
the possibility of studying a fine-tuned molecular recognition phenomenon. To evaluate the relevance of
this interaction on the folding mechanism of TRX, we characterize TRX1-93, a truncated variant of
TRX devoid of the last stretch of 15 amino acid residues that includes helix 5. TRX1-93 may possibly
represent a molecular form where the folding process becomes interrupted, giving rise to a structure
exhibiting the features of a molten globule state. This was assessed by circular dichroism, intrinsic
fluorescence, binding of the probe ANS, size-exclusion chromatography, limited proteolysis, and
calorimetry. Remarkably, fragment TRX1-93 interacts with peptide TRX94-108 (KD 2-12 íM),
bringing forth the restoration of native-like signatures and enzymic function. This represents a molecular
event of reciprocal structure selection where both partners gain order, thus leading to long-range
consequences on conformation. In this context, the binding of the C-terminal helix could signify a late
event in the consolidation of the overall TRX fold.