Catalyzes the isomerization of citrate to isocitrate via cis-aconitate. Contributes to oxidative stress tolerance (PubMed:17013749). Involved in acetate assimilation (PubMed:25061985). citrate = D-threo-isocitrate Binds 1 [4Fe-4S] cluster per subunit. Carbohydrate metabolism; tricarboxylic acid cycle; isocitrate from oxaloacetate: step 2/2. Monomer. Mostly expressed in roots, leaves and flowers, also present in stems, and, at low levels, in seeds. Slight level decrease after 3 days of iron starvation. Reduced mitochondrial aconitase (ACO) activity by 20 percent (PubMed:17013749, PubMed:17437406). Increased tolerance to oxidative stress mediated by paraquat, a superoxide-generating agent (PubMed:17013749). Altered acetate assimilation leading to lower levels of CO(2), CHO and SO, and higher OAs (organic acids) accumulation, especially fumarate (PubMed:25061985). Belongs to the aconitase/IPM isomerase family.