Desai, Kevin K.Bingman, Craig A.Cheng, Chin L.Phillips, George N. Jr.Raines, Ronald T.2014-09-302014-09-302014Desai, Kevin K., Bingman, Craig A., Cheng, Chin L., et al.. "Structure of RNA 3'-phosphate cyclase bound to substrate RNA." <i>RNA,</i> (2014) Cold Spring Harbor Laboratory Press: http://dx.doi.org/10.1261/rna.045823.114.https://hdl.handle.net/1911/77319RNA 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 Nε 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.engAvailable under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/Journal articleRtcARNA 3'-phosphate termini2',3'-cyclic phosphate terminihttp://dx.doi.org/10.1261/rna.045823.114