title: Structural studies on delta(3)-delta(2)-enoyl-CoA isomerase: the variable mode of assembly of the trimeric disks of the crotonase superfamily.
abstract: Subunits of the enzymes in the crotonase superfamily form tight trimeric disks. In most members of this protein superfamily these disks assemble further into hexamers. Here we report on the 2.1 A structure of a tight hexameric crystal form of the yeast peroxisomal delta(3)-delta(2)-enoyl-CoA isomerase (Eci1p). A comparison of this structure to a previously solved crystal form of Eci1p and other structures of this superfamily shows that there is much variability with respect to the relative distance between the disks and their relative orientations. In particular helices H2 and H9 are involved in the inter-trimer contacts and there are considerable structural differences in these helices in this superfamily. Helices H2 and H9 are near the catalytic cavity and it is postulated that the observed structural variability of these helices, stabilized by the different modes of assembly, has allowed the evolution of the wide range of substrate and catalytic specificity within this enzyme superfamily.
authors.affiliation: Biocenter Oulu and Department of Biochemistry, University of Oulu, PO Box 3000, FIN-90014 University of, Oulu, Finland.
authors.forename: Anu M
authors.initials: AM
authors.lastname: Mursula
authors.forename: J Kalervo
authors.initials: JK
authors.lastname: Hiltunen
authors.forename: Rik K
authors.initials: RK
authors.lastname: Wierenga
mesh_terms: D000595:Amino Acid Sequence; D019748:Carbon-Carbon Double Bond Isomerases / Q000737:chemistry*; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D064006:Dodecenoyl-CoA Isomerase; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D046911:Macromolecular Substances; D011994:Recombinant Proteins; D019748:Carbon-Carbon Double Bond Isomerases; D064006:Dodecenoyl-CoA Isomerase