{PDOC00423} {PS00450; ACONITASE_1} {PS01244; ACONITASE_2} {BEGIN} ******************************* * Aconitase family signatures * ******************************* Aconitase (aconitate hydratase) (EC 4.2.1.3) [1] is the enzyme from the tricarboxylic acid cycle that catalyzes the reversible isomerization of citrate and isocitrate. Cis-aconitate is formed as an intermediary 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. It has been shown that the aconitase family also contains the following proteins: - Iron-responsive element binding protein (IRE-BP). IRE-BP is 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 (EC 4.2.1.33) (isopropylmalate isomerase), the enzyme that catalyzes the second step in the biosynthesis of leucine. - Homoaconitase (EC 4.2.1.36) (homoaconitate hydratase), an enzyme that participates in the alpha-aminoadipate pathway of lysine biosynthesis and that converts cis-homoaconitate into homoisocitric acid. - Esherichia coli protein ybhJ. As a signature for proteins from the aconitase family we have selected two conserved regions that contain the three cysteine ligands of the 4Fe-4S cluster. -Consensus pattern: [LIVM]-x(2)-[GSACIVM]-x-[LIV]-[GTIV]-[STP]-C-x(0,1)-T-N- [GSTANI]-x(4)-[LIVMA] [C binds the iron-sulfur center] -Sequences known to belong to this class detected by the pattern: ALL, except for ybhJ. -Other sequence(s) detected in Swiss-Prot: NONE. -Consensus pattern: G-x(2)-[LIVWPQT]-x(3)-[GACST]-C-[GSTAM]-[LIMPTA]-C-[LIMV]- [GA] [The 2 C's bind the iron-sulfur center] -Sequences known to belong to this class detected by the pattern: ALL, except for ybhJ. -Other sequence(s) detected in Swiss-Prot: NONE. -Last update: December 2004 / Pattern and text revised. [ 1] Gruer M.J., Artymiuk P.J., Guest J.R. "The aconitase family: three structural variations on a common theme." Trends Biochem. Sci. 22:3-6(1997). PubMed=9020582 -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}