Expression and preliminary crystallographic studies of R1E, the large subunit of ribonucleotide reductase fromSalmonella typhimurium

The nrdE gene product R1E, the large subunit of the class 1b Salmonella typhimurium ribonucleotide reductase, has been overexpressed, purified and crystallized. Initially, the protein crystallized in two orthorhombic space groups, C222(1) and P2(1)2(1)2, using tartrate and PEG 6000 as precipitants, respectively. Better diffracting crystals belonging to the tetrahedral space group P4(3)2(1)2 were obtained using sodium malonate as precipitant. The P4(3)2(1)2 crystals could only be obtained after seeding from a drop containing C222(1) crystals grown in sodium tartrate. Thus, streak-seeding resulted in crystals of a supergroup to C222(1). Data to 2.8 A resolution have been collected on the P4(3)2(1)2 crystals which contained one R1E subunit in the asymmetric unit.