1jn4

The Crystal Structure of Ribonuclease A in complex with 2'-deoxyuridine 3'-pyrophosphate (P'-5') adenosine

spinqualitylabelsall models 1jn4, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1jn4 is a 2 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 139 Related: 1afk, 1afl, 1afu, 1qhc Activity: Pancreatic ribonuclease, with EC number 3.1.27.5 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [RNAS1_BOVIN] Endonuclease that catalyzes the cleavage of RNA on the 3' side of pyrimidine nucleotides. Acts on single stranded and double stranded RNA. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Recently, 3',5'-pyrophosphate-linked 2'-deoxyribodinucleotides were shown to be >100-fold more effective inhibitors of RNase A superfamily enzymes than were the corresponding monophosphate-linked (i.e., standard) dinucleotides. Here, we have investigated two ribo analogues of these compounds, cytidine 3'-pyrophosphate (P'-->5') adenosine (CppA) and uridine 3'-pyrophosphate (P'-->5') adenosine (UppA), as potential substrates for RNase A and angiogenin. CppA and UppA are cleaved efficiently by RNase A, yielding as products 5'-AMP and cytidine or uridine cyclic 2',3'-phosphate. The k(cat)/K(m) values are only 4-fold smaller than for the standard dinucleotides CpA and UpA, and the K(m) values (10-16 microM) are lower than those reported for any earlier small substrates (e.g., 500-700 microM for CpA and UpA). The k(cat)/K(m) value for CppA with angiogenin is also only severalfold smaller than for CpA, but the effect of lengthening the internucleotide linkage on K(m) is more modest. Ribonucleotide 3',5'-pyrophosphate linkages were proposed previously to exist in nature as chemically labile intermediates in the pathway for the generation of cyclic 2',3'-phosphate termini in various RNAs. We demonstrate that in fact they are relatively stable (t(1/2) > 15 days for uncatalyzed degradation of UppA at pH 6 and 25 degrees C) and that cleavage in vivo is most likely enzymatic. Replacements of the RNase A catalytic residues His12 and His119 by alanine reduce activity toward UppA by approximately 10(5)-and 10(3.3)-fold, respectively. Thus, both residues play important roles. His12 probably acts as a base catalyst in cleavage of UppA (as with RNA). However, the major function of His119 in RNA cleavage, protonation of the 5'-O leaving group, is not required for UppA cleavage because the pK(a) of the leaving group is much lower than that for RNA substrates. A crystal structure of the complex of RNase A with 2'-deoxyuridine 3'-pyrophosphate (P'-->5') adenosine (dUppA), determined at 1.7 A resolution, together with models of the UppA complex based on this structure suggest that His119 contributes to UppA cleavage through a hydrogen bond with a nonbridging oxygen atom in the pyrophosphate and through pi-pi stacking with the six-membered ring of adenine. Cleavage of 3',5'-pyrophosphate-linked dinucleotides by ribonuclease A and angiogenin.,Jardine AM, Leonidas DD, Jenkins JL, Park C, Raines RT, Acharya KR, Shapiro R Biochemistry. 2001 Aug 28;40(34):10262-72. PMID:11513604 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease Temp

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