To be active, all sulfatases require a maturation process, this is the group of proteins that perform this maturation. The proteins in this family are thought to favour the Ser-type sulfatases. It is not clear in the literature how the SAM moiety is used, whether it is catalytic or stoichiometric.
Benjdia A, Subramanian S, Leprince J, Vaudry H, Johnson MK, Berteau O
Anaerobic sulfatase-maturating enzymes, first dual substrate radical S-adenosylmethionine enzymes
▸ Abstract
Sulfatases are a major group of enzymes involved in many critical physiological processes as reflected by their broad distribution in all three domains of life. This class of hydrolases is unique in requiring an essential post-translational modification of a critical active-site cysteine or serine residue to C(alpha)-formylglycine. This modification is catalyzed by at least three nonhomologous enzymatic systems in bacteria. Each enzymatic system is currently considered to be dedicated to the modification of either cysteine or serine residues encoded in the sulfatase-active site and has been accordingly categorized as Cys-type and Ser-type sulfatase-maturating enzymes. We report here the first detailed characterization of two bacterial anaerobic sulfatase-maturating enzymes (anSMEs) that are physiologically responsible for either Cys-type or Ser-type sulfatase maturation. The activity of both enzymes was investigated in vivo and in vitro using synthetic substrates and the successful purification of both enzymes facilitated the first biochemical and spectroscopic characterization of this class of enzyme. We demonstrate that reconstituted anSMEs are radical S-adenosyl-l-methionine enzymes containing a redox active [4Fe-4S](2+,+) cluster that initiates the radical reaction by binding and reductively cleaving S-adenosyl-l-methionine to yield 5 '-deoxyadenosine and methionine. Surprisingly, our results show that anSMEs are dual substrate enzymes able to oxidize both cysteine and serine residues to C(alpha)-formylglycine. Taken together, the results support a radical modification mechanism that is initiated by hydrogen abstraction from a serine or cysteine residue located in an appropriate target sequence.
Benjdia A, Leprince J, Guillot A, Vaudry H, Rabot S, Berteau O
Anaerobic sulfatase-maturating enzymes: radical SAM enzymes able to catalyze in vitro sulfatase post-translational modification
▸ Abstract
Sulfatases are widespread enzymes, found from prokaryotes to eukaryotes and involved in many biochemical processes. To be active, all known sulfatases undergo a unique post-translational modification leading to the conversion of a critical active-site residue, i.e., a serine or a cysteine, into a Cα-formylglycine (FGly). Two different systems are involved in sulfatase maturation. One, named FGE, is an oxygen-dependent oxygenase and has been fully characterized. The other one, a member of the so-called “radical SAM” super-family, has been only preliminary investigated. This latter system allows the maturation of sulfatases in strictly anaerobic conditions and has thus been named anSME (anaerobic Sulfatase Maturating Enzyme). Our results provide the first experimental evidence that anSME are iron−sulfur enzymes able to perform the reductive cleavage of SAM and thus belong to the radical SAM super-family. Furthermore, they demonstrate that anSME are able to efficiently oxidize cysteine into FGly in an oxygen-independent manner.
J Am Chem Soc
2007;129(12):3462-3463
| PubMed ID:
17335281
