4o8j
From Proteopedia
Crystal structure of RtcA, the RNA 3'-terminal phosphate cyclase from Pyrococcus horikoshii, in complex with rACAAA3'phosphate and adenine.
Structural highlights
FunctionRTCA_PYRHO Catalyzes the conversion of 3'-phosphate to a 2',3'-cyclic phosphodiester at the end of RNA. The mechanism of action of the enzyme occurs in 3 steps: (A) adenylation of the enzyme by ATP; (B) transfer of adenylate to an RNA-N3'P to produce RNA-N3'PP5'A; (C) and attack of the adjacent 2'-hydroxyl on the 3'-phosphorus in the diester linkage to produce the cyclic end product. The biological role of this enzyme is unknown but it is likely to function in some aspects of cellular RNA processing (By similarity). Publication Abstract from PubMedRNA 3'-phosphate cyclase (RtcA) catalyzes the ATP-dependent cyclization of a 3'-phosphate to form a 2',3'-cyclic phosphate at RNA termini. Cyclization proceeds through RtcA-AMP and RNA(3')pp(5')A covalent intermediates, which are analogous to intermediates formed during catalysis by the tRNA ligase RtcB. Here we present a crystal structure of Pyrococcus horikoshii RtcA in complex with a 3'-phosphate terminated RNA and adenosine in the AMP-binding pocket. Our data reveal that RtcA recognizes substrate RNA by ensuring that the terminal 3'-phosphate makes a large contribution to RNA binding. Furthermore, the RNA 3'-phosphate is poised for in-line attack on the P-N bond that links the phosphorous atom of AMP to N of His307. Thus, we provide the first insights into RNA 3'-phosphate termini recognition and the mechanism of 3'-phosphate activation by an Rtc enzyme. Structure of RNA 3'-phosphate cyclase bound to substrate RNA.,Desai KK, Bingman CA, Cheng CL, Phillips GN Jr, Raines RT RNA. 2014 Aug 26. PMID:25161314[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found References
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