NMR solution structure of a novel thioredoxin from Bacillus acidocaldarius

• DOI: 10.1046/j.1432-1327.2000.01015.x
• Publication Date: 2003-03-11T17:55:41Z
• Authors: Giuseppe Nicastro; Cesira de Chiara; Emilia Pedone; Marco Tatò; Mosè Rossi; Simonetta Bartolucci
• Keywords: Thermostability; Dihedral angle

The thioredoxin (Trx) from Bacillus acidocaldarius (BacTrx), an eubacterium growing optimally at 333 K, is the first Trx described to date a moderate thermophilic source. To understand molecular basis of its thermostability, three‐dimensional structure in oxidized form was determined by NMR methods. A total 2276 1 H‐NMR derived distance constraints along with 23 hydrogen‐bonds, 72 φ and 27 χ torsion angle restraints, were used protocol employing simulated annealing followed restrained dynamics energy minimization. BacTrx consists well‐defined core region five strands β‐sheet, surrounded four exposed α‐helices, features shared other members family. 3D compared Escherichia coli (EcTrx) X‐ray crystallographic diffraction, number structural differences observed that may contribute thermostabilty. results analysis indicated protein stability due cumulative effects, main factor being increased ionic interactions cross‐linking different secondary elements clamping C‐terminal α‐helix protein.