Preliminary crystallographic analysis of theEscherichia coliantitoxin MqsA (YgiT/b3021) in complex withmqsRApromoter DNA
TheEscherichia coliproteins MqsR and MqsA comprise a novel toxin–antitoxin (TA) system. MqsA, the antitoxin, defines a new family of antitoxins because unlike other antitoxins MqsA is structured throughout its entire sequence, binds zinc and coordinates DNAviaits C-terminal and not its N-terminal domain. In order to understand how bacterial antitoxins, and MqsA in particular, regulate transcription, the MqsA protein was cocrystallized with a 26-mer duplex DNA corresponding to the palindromic region of themqsRApromoter. The merohedrally twinned crystal belonged to space groupP41, with unit-cell parametersa= 60.99,b= 60.99,c= 148.60 Å. A complete data set was collected to a resolution of 2.1 Å. The solvent content of the crystal was consistent with the presence of two MqsA molecules bound to the duplex DNA in the asymmetric unit.