OrfAB[1-149] synapses right inverted repeat (IRR) (100 bp) as a dimer. Electromobility shift assay (EMSA) analysis of the binding of OrfAB[1-149] (dark ball) and TrxA- OrfAB[1-149] (dark ball with a tag) to a 100 bp fragment composed of IRR and flanking DNA (large and small grey cylinders respectively). Radiolabeled IRR containing DNA fragments (20 nM) were incubated with OrfAB[1-149] and/or TrxA-OrfAB[1-149] (final protein concentration of 500 nM in lanes 2-4). Reactions were separated in 5% native polyacrylamide gels (12 V/cm), and at least six complexes (from complexes I-VI) visualised. A model for complex stoichiometry is proposed and discussed in the text.