bi982647q_si_001.pdf (262.13 kB)
Structural and Dynamical Properties of a Partially Unfolded Fe4S4 Protein: Role of the Cofactor in Protein Folding†
journal contribution
posted on 1999-03-24, 00:00 authored by Detlef Bentrop, Ivano Bertini, Rita Iacoviello, Claudio Luchinat, Yohei Niikura, Mario Piccioli, Chiara Presenti, Antonio RosatoHeteronuclear multidimensional NMR spectroscopy was used to investigate in detail the
structural and dynamical properties of a partially unfolded intermediate of the reduced high-potential
iron−sulfur protein (HiPIP) from Chromatium vinosum present in 4 M guanidinium chloride solution.
After an extensive assignment of 15N and 1H resonances, NOE data, proton longitudinal relaxation times,
and 3JHNHα coupling constants as well as 15N relaxation parameters (T1, T2, T1ρ, and 1H−15N NOE) were
obtained and used to build a structural model of the intermediate. The Fe4S4 cluster of the HiPIP plays
a decisive role in determining the resulting structure, which is random in the N-terminal half of the protein
and partially organized in the loops between the cysteines bound to the cluster. Consistent with the structural
data, the backbone mobility is typical of folded proteins in the regions where there are elements of structure
and increases with the structural indetermination.