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Eukaryotic formylglycine‐generating enzyme catalyses a monooxygenase type of reaction
Author(s) -
Peng Jianhe,
Alam Sarfaraz,
Radhakrishnan Karthikeyan,
Mariappan Malaiyalam,
Rudolph Markus Georg,
May Caroline,
Dierks Thomas,
Figura Kurt,
Schmidt Bernhard
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13347
Subject(s) - cysteine , endoplasmic reticulum , chemistry , residue (chemistry) , monooxygenase , enzyme , biochemistry , stereochemistry , active site , cofactor , cytochrome p450
C α‐formylglycine ( FG ly) is the catalytic residue of sulfatases in eukaryotes. It is generated by a unique post‐translational modification catalysed by the FG ly‐generating enzyme ( FGE ) in the endoplasmic reticulum. FGE oxidizes a cysteine residue within the conserved CxPxR sequence motif of nascent sulfatase polypeptides to FG ly. Here we show that this oxidation is strictly dependent on molecular oxygen (O 2 ) and consumes 1 mol O 2 per mol FG ly formed. For maximal activity FGE requires an O 2 concentration of 9% (105 μ m ). Sustained FGE activity further requires the presence of a thiol‐based reductant such as DTT . FG ly is also formed in the absence of DTT , but its formation ceases rapidly. Thus inactivated FGE accumulates in which the cysteine pair Cys336/Cys341 in the catalytic site is oxidized to form disulfide bridges between either Cys336 and Cys341 or Cys341 and the CxPxR cysteine of the sulfatase. These results strongly suggest that the Cys336/Cys341 pair is directly involved in the O 2 ‐dependent conversion of the CxPxR cysteine to FG ly. The available data characterize eukaryotic FGE as a monooxygenase, in which Cys336/Cys341 disulfide bridge formation donates the electrons required to reduce one oxygen atom of O 2 to water while the other oxygen atom oxidizes the CxPxR cysteine to FG ly. Regeneration of a reduced Cys336/Cys341 pair is accomplis‐hed in vivo by a yet unknown reductant of the endoplasmic reticulum or in vitro by DTT . Remarkably, this monooxygenase reaction utilizes O 2 without involvement of any activating cofactor.