Bacterial Aconitase-like swivel domain. Aconitase (aconitate hydratase or citrate hydrolyase) catalyzes the reversible isomerization of citrate and isocitrate as part of the TCA cycle. Cis-aconitate is formed as an intermediate product during the course of the reaction. This is the aconitase-like swivel domain, which is believed to undergo swivelling conformational change in the enzyme mechanism. This distinct subfamily is found only in bacteria and archea. Its exact characteristics are not known.