Abstract
The multiple antibiotic resistance operon (marRAB) is a member of the multidrug-resistance system. When induced, this operon enhances resistance of bacteria to a variety of medically important antibiotics, causing a serious global health problem. MarR is a marR-encoded protein that represses the transcription of the marRAB operon. Through binding with salicylate and certain antibiotics, however, MarR can derepress and activate the marRAB operon. In this report, the cloning, expression, crystallization and preliminary X-ray analysis of XC1739, a putative MarR repressor protein present in the Xanthomonas campestris pv. campestris, a Gram-negative bacterium causing major worldwide disease of cruciferous crops, are described. The XC1739 crystals diffracted to a resolution of at least 1.8 A. They are orthorhombic and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 39.5, b = 54.2 and c = 139.5 A, respectively. They contain two molecules in the asymmetric unit from calculation of the self-rotation function.