1rds
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CRYSTAL STRUCTURE OF RIBONUCLEASE MS (AS RIBONUCLEASE T1 HOMOLOGUE) COMPLEXED WITH A GUANYLYL-3',5'-CYTIDINE ANALOGUE
OverviewOverview
A ribonuclease T1 homologue, ribonuclease Ms (RNase Ms) from Aspergillus, saitoi, has been crystallized as a complex with a substrate analogue GfpC, where the 2'-hydroxyl (2'-OH) group of guanosine in, guanylyl-3',5'-cytidine (GpC) is replaced by the 2'-fluorine (2'-F) atom, to prevent transesterification. The crystal structure of the complex was, solved at 1.8-A resolution to a final R-factor of 0.204. The role of His92, (RNase T1 numbering) as the general acid catalyst was confirmed. Of the, two alternative candidates for a general base to abstract a proton from, the 2'-OH group, His40 and Glu58 were found close to the 2'-F atom, making, the decision between the two groups difficult. We then superposed the, active site of the RNase Ms/GfpC complex with that of pancreatic, ribonuclease S (RNase S) complexed with a substrate analogue UpcA, a, phosphonate analogue of uridylyl-3',5'-adenosine (UpA), and found that, His12 and His119 of RNase A almost exactly coincided with Glu58 and His92, respectively, of RNase Ms. Similar superposition with a prokaryotic, microbial ribonuclease, RNase St [Nakamura, K. T., Iwahashi, K., Yamamoto, Y., Iitaka, Y., Yoshida, N., & Mitsui, Y. (1982) Nature 299, 564-566], also indicated Glu58 as a general base. Thus the present comparative, geometrical studies consistently favor, albeit indirectly, the traditional, as well as the most recent notion [Steyaert, J., Hallenga, K., Wyns, L., &, Stanssens, P. (1990) Biochemistry 29, 9064-9072] that Glu58, rather than, His40, must be the general base catalyst in the intact enzymes of the, RNase T1 family.
About this StructureAbout this Structure
1RDS is a Single protein structure of sequence from Aspergillus phoenicis with GPC as ligand. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of ribonuclease Ms (as a ribonuclease T1 homologue) complexed with a guanylyl-3',5'-cytidine analogue., Nonaka T, Nakamura KT, Uesugi S, Ikehara M, Irie M, Mitsui Y, Biochemistry. 1993 Nov 9;32(44):11825-37. PMID:8218254
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