Aconitase catalytic domain; Aconitase catalyzes the reversible isomerization of citrate and isocitrate as part of the TCA cycle
Aconitase catalytic domain. Aconitase (aconitate hydratase) 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. In eukaryotes two isozymes of aconitase are known to exist: one found in the mitochondrial matrix and the other found in the cytoplasm. Aconitase, in its active form, contains a 4Fe-4S iron-sulfur cluster; three cysteine residues have been shown to be ligands of the 4Fe-4S cluster. This is the Aconitase core domain, including structural domains 1, 2 and 3, which binds the Fe-S cluster. The aconitase family also contains the following proteins: - Iron-responsive element binding protein (IRE-BP), a cytosolic protein that binds to iron-responsive elements (IREs). IREs are stem-loop structures found in the 5'UTR of ferritin, and delta aminolevulinic acid synthase mRNAs, and in the 3'UTR of transferrin receptor mRNA. IRE-BP also express aconitase activity. - 3-isopropylmalate dehydratase (isopropylmalate isomerase), the enzyme that catalyzes the second step in the biosynthesis of leucine. - Homoaconitase (homoaconitate hydratase), an enzyme that participates in the alpha-aminoadipate pathway of lysine biosynthesis and that converts cis-homoaconitate into homoisocitric acid.