title: Structural and stability characteristics of a monothiol glutaredoxin: glutaredoxin-like protein 1 from Plasmodium falciparum.
abstract: Recently discovered monothiol glutaredoxins with CXXS-active site sequence share a common structural motif and biochemical mechanism of action and are involved in multiple cellular functions. Here we report first studies on the structural and stability characterization of a monothiol glutaredoxin, in particular--PfGLP1. Our results demonstrate that in the native conformation, the enzyme has a compact core structure with a relatively flexible N-terminal portion having an open configuration. Comparative functional studies with the full-length and N-terminal truncated protein demonstrate that the flexible N-terminal portion does not play any significant role in functional activity of the protein. In contrast to other Grxs, PfGLP1 does not contain a Fe-S cluster. The pH dependent studies demonstrate that the protein is resistant to alkaline pH but highly sensitive to acidic pH and undergoes significant unfolding between pH 4 and 5. However, acidic conditions also do not induce complete unfolding of the enzyme. The protein is stabilized with a conformational free energy of about 3.2+/-0.1 kcal mol(-1). The protein is a highly cooperative molecule as during denaturant-induced equilibrium unfolding a simultaneous unfolding of the protein without stabilization of any partially folded intermediate is observed.
authors.affiliation: Division of Molecular and Structural Biology, Central Drug Research Institute, Lucknow, India.
authors.forename: Timir
authors.initials: T
authors.lastname: Tripathi
authors.forename: Stefan
authors.initials: S
authors.lastname: Rahlfs
authors.forename: Katja
authors.initials: K
authors.lastname: Becker
authors.forename: Vinod
authors.initials: V
authors.lastname: Bhakuni
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D054477:Glutaredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011485:Protein Binding; D011489:Protein Denaturation; D011522:Protons; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D054477:Glutaredoxins; D011522:Protons; D015800:Protozoan Proteins