3TCO

Crystallographic and spectroscopic characterization of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability

Summary for 3TCO

• Entry DOI: 10.2210/pdb3tco/pdb
• Descriptor: Thioredoxin (TrxA-1), 1,2-ETHANEDIOL (3 entities in total)
• Functional Keywords: disulfide oxidoreductase, oxidoreductase
• Biological source: Sulfolobus solfataricus
• Total number of polymer chains: 3
• Total formula weight: 37895.31

Authors

Esposito, L.,Ruggiero, A.,Masullo, M.,Ruocco, M.R.,Lamberti, A.,Arcari, P.,Zagari, A.,Vitagliano, L. (deposition date: 2011-08-09, release date: 2011-11-30, Last modification date: 2024-11-20)

Primary citation

Esposito, L.,Ruggiero, A.,Masullo, M.,Ruocco, M.R.,Lamberti, A.,Arcari, P.,Zagari, A.,Vitagliano, L.
Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability.
J.Struct.Biol., 177:506-512, 2012

PubMed Abstract: Structural characterizations of thioredoxins (Trxs) are important for their involvement in severe pathologies and for their stable scaffold. Here we report a combined structural and spectroscopic characterization of a Trx isolated from the hyperthermophilic archaeon Sulfolobus solfataricus (SsTrxA1). Thermal denaturation unveils that SsTrxA1 is endowed with a remarkable stability in the explored temperature range 50-105°C. The structure of the oxidized form of SsTrxA1 determined at 1.9Å resolution presents a number of peculiar features. Although the protein was crystallized in a slightly acid medium (pH 6.5) as many as ten intramolecular/intermolecular carboxyl-carboxylate interactions involving glutamic and aspartic acid side chains are found in three independent SsTrxA1 molecules present in the asymmetric unit. Surprisingly for a hyperthermostable protein, the structure of SsTrxA1 is characterized by the presence (a) of a very limited number of intramolecular salt bridges and (b) of a cavity nearby Cys52, a residue that is frequently a phenylananine in other members of the family. Chemical denaturation investigations carried out on SsTrxA1 and SsTrxA2 show that both proteins present a significant stability against guanidine hydrochloride, thus indicating that ionic interactions play a minor role in their stabilization. Compared to Trxs from mesophilic sources, SsTrxA1 displays a longer α-helix 1 and a shorter loop connecting this α-helix with β-strand 2. As these features are shared with Trxs isolated from thermophilic sources, the shortening of this loop may be a general strategy adopted to stabilize this fold. This feature may be exploited for the design of hyperthermostable Trx scaffolds.

PubMed: 22085748
DOI: 10.1016/j.jsb.2011.10.014

Experimental method

X-RAY DIFFRACTION (1.9 Å)