Structure and mechanism of the 2′,3′ phosphatase component of the bacterial Pnkp-Hen1 RNA repair system

摘要: Pnkp is the end-healing and end-sealing component of an RNA repair system present in diverse bacteria from many phyla. composed three catalytic modules: N-terminal polynucleotide 5′ kinase, a central 2′,3′ phosphatase C-terminal ligase. The module Mn2+-dependent phosphodiesterase–monoesterase that dephosphorylates 2′,3′-cyclic phosphate ends. Here we report crystal structure domain Clostridium thermocellum with Mn2+ citrate active site. protein consists core binuclear metallo-phosphoesterase fold (exemplified by bacteriophage λ phosphatase) embellished distinctive secondary elements. site contains single octahedral coordination complex Asp187, His189, Asp233, two oxygens water. fills binding for scissile phosphate, wherein it coordinated Arg237, Asn263 His264. invades normally occupied second metal (engaged Asn263, His323 His376), thereby dislocates His376. A continuous tract positive surface potential flanking suggests illuminates large body mutational data regarding substrate specificity phosphatase.