Crystal structure of the Entamoeba histolytica RNA lariat debranching enzyme EhDbr1 reveals a catalytic Zn2+ /Mn2+ heterobinucleation.
The RNA lariat debranching enzyme, Dbr1, is a metallophosphoesterase that cleaves 2'-5' phosphodiester bonds within intronic lariats. Previous reports have indicated that Dbr1 enzymatic activity is supported by diverse metal ions including Ni2+ , Mn2+ , Mg2+ , Fe2+ , and Zn2+ . While in initial structures of the Entamoeba histolytica Dbr1 only one of the two catalytic metal-binding sites were observed to be occupied (with a Mn2+ ion), recent structures determined a Zn2+ /Fe2+ heterobinucleation. We solved a high-resolution X-ray crystal structure (1.8 Å) of the E. histolytica Dbr1 and determined a Zn2+ /Mn2+ occupancy. ICP-AES corroborate this finding, and in vitro debranching assays with fluorescently labeled branched substrates confirm activity.
['Ransey|Elizabeth|E|', 'Paredes|Eduardo|E|', 'Dey|Sourav K|SK|', 'Das|Subha R|SR|', 'Heroux|Annie|A|', 'Macbeth|Mark R|MR|']
D055162:Biocatalysis D020134:Catalytic Domain D018360:Crystallography, X-Ray D004748:Entamoeba histolytica D008345:Manganese D008958:Models, Molecular D012316:RNA Nucleotidyltransferases D015032:Zinc
heterobinucleation metallophosphoesterase ICP-AES