Unanticipated coordination of tris buffer to the Radical SAM cluster of the RimO methylthiotransferase

作者：Molle Thibaut; Clemancey Martin; Latour Jean Marc; Kathirvelu Velavan; Sicoli Giuseppe; Forouhar Farhad; Mulliez Etienne^*; Gambarelli Serge^*; Atta Mohamed^*

来源：Journal of Biological Inorganic Chemistry, 2016, 21(4): 549-557.

DOI：10.1007/s00775-016-1365-8

• Biosynthesis
• Cofactor
• Electron paramagnetic resonance
• Iron-sulfur cluster
• Ligand binding
• Mossbauer spectroscopy
• Pulsed EPR

Radical SAM enzymes generally contain a [4Fe-4S](2+/1+) (RS cluster) cluster bound to the protein via the three cysteines of a canonical motif CxxxCxxC. The non-cysteinyl iron is used to coordinate SAM via its amino-carboxylate moiety. The coordination-induced proximity between the cluster acting as an electron donor and the adenosyl-sulfonium bond of SAM allows for the homolytic cleavage of the latter leading to the formation of the reactive 5'-deoxyadenosyl radical used for substrate activation. Most of the structures of Radical SAM enzymes have been obtained in the presence of SAM, and therefore, little is known about the situation when SAM is not present. In this report, we show that RimO, a methylthiotransferase belonging to the radical SAM superfamily, binds a Tris molecule in the absence of SAM leading to specific spectroscopic signatures both in Mossbauer and pulsed EPR spectroscopies. These data provide a cautionary note for researchers who work with coordinative unsaturated iron sulfur clusters.

• 出版日期2016-7
• 单位中国地震局