The crystal structure of plant sulfite oxidase provides insights into sulfite oxidation in plants and animals.
The molybdenum cofactor (Moco) containing sulfite oxidase (SO) from Arabidopsis thaliana has recently been identified and biochemically characterized. The enzyme is found in peroxisomes and believed to detoxify excess sulfite that is produced during sulfur assimilation, or due to air pollution. Plant SO (PSO) is homodimeric and homologous to animal SO, but contains only a single Moco domain without an additional redox center. Here, we present the first crystal structure of a plant Moco enzyme, the apo-state of Arabidopsis SO at 2.6 A resolution. The overall fold and coordination of the Moco are similar to chicken SO (CSO). Comparisons of conserved surface residues and the charge distribution in PSO and CSO reveal major differences near the entrance to both active sites reflecting different electron acceptors. Arg374 has been identified as an important substrate binding residue due to its conformational change when compared to the sulfate bound structure of CSO.
Schrader
Nils
N
Department of Pharmacological Sciences, Center for Structural Biology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
Fischer
Katrin
K
Theis
Karsten
K
Mendel
Ralf R
RR
Schwarz
Günter
G
Kisker
Caroline
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D001665:Binding Sites; D019281:Dimerization; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013447:Sulfites / Q000378:metabolism
D013447:Sulfites; D008982:Molybdenum; D050862:Oxidoreductases Acting on Sulfur Group Donors