1hy0
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CRYSTAL STRUCTURE OF WILD TYPE DUCK DELTA 1 CRYSTALLIN (EYE LENS PROTEIN)
OverviewOverview
Duck delta1 and delta2 crystallin are 94% identical in amino acid, sequence, and while delta2 crystallin is the duck orthologue of, argininosuccinate lyase (ASL) and catalyzes the reversible breakdown of, argininosuccinate to arginine and fumarate, the delta1 isoform is, enzymatically inactive. The crystal structures of wild type duck delta1, and delta2 crystallin have been solved at 2.2 and 2.3 A resolution, respectively, and the refinement of the turkey delta1 crystallin has been, completed. These structures have been compared with two mutant duck delta2, crystallin structures. Conformational changes were observed in two regions, of the N-terminal domain with intraspecies differences between the active, and inactive isoforms localized to residues 23-32 and both intra- and, interspecies differences localized to the loop of residues 74-89. As the, residues implicated in the catalytic mechanism of delta2/ASL are all, conserved in delta1, the amino acid substitutions in these two regions are, hypothesized to be critical for substrate binding. A sulfate anion was, found in the active site of duck delta1 crystallin. This anion, which, appears to mimic the fumarate moiety of the argininosuccinate substrate, induces a rigid body movement in domain 3 and a conformational change in, the loop of residues 280-290, which together would sequester the substrate, from the solvent. The duck delta1 crystallin structure suggests that Ser, 281, a residue strictly conserved in all members of the superfamily, could, be the catalytic acid in the delta2 crystallin/ASL enzymatic mechanism.
About this StructureAbout this Structure
1HY0 is a Single protein structure of sequence from Anas platyrhynchos with SO4 as ligand. Active as Argininosuccinate lyase, with EC number 4.3.2.1 Full crystallographic information is available from OCA.
ReferenceReference
Structural studies of duck delta 1 and delta 2 crystallin suggest conformational changes occur during catalysis., Sampaleanu LM, Vallee F, Slingsby C, Howell PL, Biochemistry. 2001 Mar 6;40(9):2732-42. PMID:11258884
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