On the Role of Additional [4Fe-4S] Clusters with a Free Coordination Site in Radical-SAM Enzymes
نویسندگان
چکیده
The canonical CysXXXCysXXCys motif is the hallmark of the Radical-SAM superfamily. This motif is responsible for the ligation of a [4Fe-4S] cluster containing a free coordination site available for SAM binding. The five enzymes MoaA, TYW1, MiaB, RimO and LipA contain in addition a second [4Fe-4S] cluster itself bound to three other cysteines and thus also displaying a potentially free coordination site. This review article summarizes recent important achievements obtained on these five enzymes with the main focus to delineate the role of this additional [4Fe-4S] cluster in catalysis.
منابع مشابه
Structural studies of the interaction of S-adenosylmethionine with the [4Fe-4S] clusters in biotin synthase and pyruvate formate-lyase activating enzyme.
The diverse reactions catalyzed by the radical-SAM superfamily of enzymes are thought to proceed via a set of common mechanistic steps, key among which is the reductive cleavage of S-adenosyl-L-methionine (SAM) by a reduced [4Fe-4S] cluster to generate an intermediate deoxyadenosyl radical. A number of spectroscopic studies have provided evidence that SAM interacts directly with the [4Fe-4S] cl...
متن کاملCoordination of adenosylmethionine to a unique iron site of the [4Fe-4S] of pyruvate formate-lyase activating enzyme: a Mössbauer spectroscopic study.
Pyruvate formate-lyase activating enzyme (PFL-AE) generates the catalytically essential glycyl radical of PFL. It is a member of the so-called "radical-SAM superfamily" of enzymes that use a [4Fe-4S] cluster and S-adenosylmethionine (AdoMet or SAM) to catalyze diverse radical-mediated reactions. Evidence suggests that this class of enzymes operate by common initial steps involving the generatio...
متن کاملRadical S-Adenosylmethionine Enzymes
ing a H-atom from substrate. These and other kinetics studies demonstrated that PFL-AE could undergo multiple turnover events, with the 150 PFL activations per PFL-AE reported in Table 1 not the upper limit, but rather a number limited by the PFL:PFL-AE ratio in the steady-state kinetics assays. As can be seen from the data summarized in Table 1, PFL-AE is one of the few radical SAM enzymes dem...
متن کاملCharacterization of auxiliary iron–sulfur clusters in a radical S‐adenosylmethionine enzyme PqqE from Methylobacterium extorquens AM1
PqqE is a radical S-adenosyl-l-methionine (SAM) enzyme that catalyzes the initial reaction of pyrroloquinoline quinone (PQQ) biosynthesis. PqqE belongs to the SPASM (subtilosin/PQQ/anaerobic sulfatase/mycofactocin maturating enzymes) subfamily of the radical SAM superfamily and contains multiple Fe-S clusters. To characterize the Fe-S clusters in PqqE from Methylobacterium extorquens AM1, Cys r...
متن کاملSpectroscopic approaches to elucidating novel iron-sulfur chemistry in the "radical-Sam" protein superfamily.
Electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), and Mössbauer spectroscopies and other physical methods have provided important new insights into the radical-SAM superfamily of proteins, which use iron-sulfur clusters and S-adenosylmethionine to initiate H atom abstraction reactions. This remarkable chemistry involves the generation of the extremely reactive 5'...
متن کامل