Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability
Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability(457 views) Esposito L, Ruggiero A, Masullo M, Ruocco MR, Lamberti A, Arcari P, Zagari A, Vitagliano L
Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, I-80134 Napoli, Italy
Dipartimento delle Scienze Biologiche, Sezione di Biostrutture, Università degli Studi di Napoli Federico II, Via Mezzocannone 16, I-80134 Napoli, Italy
Dipartimento di Studi delle Istituzioni e dei Sistemi Territoriali, Università degli Studi di Napoli Parthenope, Via Medina 40, 80133 Napoli, Italy
Dipartimento di Biochimica e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Via S. Pansini 5, I-80131 Napoli, Italy
CEINGE Biotecnologie Avanzate s.c.a r.l., Via Gaetano Salvatore 486, I-80145 Napoli, Italy
References: Not available.
Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability
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 degrees C. The structure of the oxidized form of SsTrxA1 determined at 1.9 angstrom 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 alpha-helix 1 and a shorter loop connecting this alpha-helix with beta-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 Inc scaffolds. (C) 2011 Elsevier Inc. All rights reserved.
Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability
Crystallographic and spectroscopic characterizations of Sulfolobus solfataricus TrxA1 provide insights into the determinants of thioredoxin fold stability