title: QSOX contains a pseudo-dimer of functional and degenerate sulfhydryl oxidase domains.
abstract: Quiescin sulfhydryl oxidase (QSOX) catalyzes formation of disulfide bonds between cysteine residues in substrate proteins. Human QSOX1 is a multi-domain, monomeric enzyme containing a module related to the single-domain sulfhydryl oxidases of the Erv family. A partial QSOX1 crystal structure reveals a single-chain pseudo-dimer mimicking the quaternary structure of Erv enzymes. However, one pseudo-dimer "subunit" has lost its cofactor and catalytic activity. In QSOX evolution, a further concatenation to a member of the protein disulfide isomerase family resulted in an enzyme capable of both disulfide formation and efficient transfer to substrate proteins.
authors.affiliation: Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Assaf
authors.initials: A
authors.lastname: Alon
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Heckler
authors.forename: Colin
authors.initials: C
authors.lastname: Thorpe
authors.forename: Deborah
authors.initials: D
authors.lastname: Fass
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D010088:Oxidoreductases / Q000737:chemistry*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary
chemical_list: D010088:Oxidoreductases; D050862:Oxidoreductases Acting on Sulfur Group Donors; D010446:Peptide Fragments; C117183:QSOX1 protein, human