The emergence of bacterial resistance to multiple drugs poses a serious and growing health concern. Understanding and deciphering the mechanisms of these multiple drug resistance regulatory proteins through structural or biochemical means is an important endeavor. Here, we present the crystal structure of ST1710 from Sulfolobus tokodaii strain 7 in two different crystal forms, at 1.80 and 2.0 angstrom, respectively. The overall structure of the ST1710 dimer shares the topology of the MarR family of proteins, with each subunit containing a winged helix-turn-helix DNA-binding motif. We also show the protein-DNA interactions by biochemical methods. Our molecular modeling analysis suggested that Asp88 and Arg90 are the key residues in ST1710 involved in the protein-DNA interactions. (c) 2007 Elsevier Inc. All rights reserved.