<p> This entry represents Fe/S-dependent 2-methylisocitrate dehydratase (AcnD; <db_xref db="EC" dbkey="4.2.1.99"/>), which is part of the 2-methylcitrate (2-MC) cycle that occurs in certain fungi and bacteria. The 2-MC cycle is involved in the degradation of propionyl-CoA via 2-methylcitrate, with AcnD functioning after PrpD and before PrpB. AcnD acts to catalyse the dehydration of 2-methylcitrate and citrate to 2-methyl-cis-aconitate and cis-aconitate, respectively, as well as to catalyse the hydration of cis-aconitate. However, 2-methylisocitrate and isocitrate were not substrates for AcnD, indicating that AcnD only catalyses the first half of the aconitase-like dehydration reactions [<cite idref="PUB00017755"/>]. The enzyme from the fungus <taxon tax_id="4952">Yarrowia lipolytica</taxon> (Candida lipolytica) does not act on isocitrate. AcnD is homologous to aconitases A and B. In <taxon tax_id="562">Escherichia coli</taxon>, which lacks a member of this family, 2-methylisocitrate dehydratase activity was traced to aconitase B (<db_xref db="INTERPRO" dbkey="IPR004406"/>) [<cite idref="PUB00016694"/>].</p><p>Information about related proteins can be found at Protein of the Month: Aconitase [<cite idref="PUB00036022"/>].</p> 2-methylisocitrate dehydratase AcnD, Fe/S-dependent