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| - | [[Image:1b2m.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1b2m| PDB=1b2m | SCENE= }} | | {{STRUCTURE_1b2m| PDB=1b2m | SCENE= }} |
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| - | '''THREE-DIMENSIONAL STRUCTURE OF RIBONULCEASE T1 COMPLEXED WITH AN ISOSTERIC PHOSPHONATE ANALOGUE OF GPU: ALTERNATE SUBSTRATE BINDING MODES AND CATALYSIS.'''
| + | ===THREE-DIMENSIONAL STRUCTURE OF RIBONULCEASE T1 COMPLEXED WITH AN ISOSTERIC PHOSPHONATE ANALOGUE OF GPU: ALTERNATE SUBSTRATE BINDING MODES AND CATALYSIS.=== |
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| - | ==Overview==
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| - | The X-ray crystal structure of a complex between ribonuclease T1 and guanylyl(3'-6')-6'-deoxyhomouridine (GpcU) has been determined at 2. 0 A resolution. This ligand is an isosteric analogue of the minimal RNA substrate, guanylyl(3'-5')uridine (GpU), where a methylene is substituted for the uridine 5'-oxygen atom. Two protein molecules are part of the asymmetric unit and both have a GpcU bound at the active site in the same manner. The protein-protein interface reveals an extended aromatic stack involving both guanines and three enzyme phenolic groups. A third GpcU has its guanine moiety stacked on His92 at the active site on enzyme molecule A and interacts with GpcU on molecule B in a neighboring unit via hydrogen bonding between uridine ribose 2'- and 3'-OH groups. None of the uridine moieties of the three GpcU molecules in the asymmetric unit interacts directly with the protein. GpcU-active-site interactions involve extensive hydrogen bonding of the guanine moiety at the primary recognition site and of the guanosine 2'-hydroxyl group with His40 and Glu58. On the other hand, the phosphonate group is weakly bound only by a single hydrogen bond with Tyr38, unlike ligand phosphate groups of other substrate analogues and 3'-GMP, which hydrogen-bonded with three additional active-site residues. Hydrogen bonding of the guanylyl 2'-OH group and the phosphonate moiety is essentially the same as that recently observed for a novel structure of a RNase T1-3'-GMP complex obtained immediately after in situ hydrolysis of exo-(Sp)-guanosine 2',3'-cyclophosphorothioate [Zegers et al. (1998) Nature Struct. Biol. 5, 280-283]. It is likely that GpcU at the active site represents a nonproductive binding mode for GpU [Steyaert, J., and Engleborghs (1995) Eur. J. Biochem. 233, 140-144]. The results suggest that the active site of ribonuclease T1 is adapted for optimal tight binding of both the guanylyl 2'-OH and phosphate groups (of GpU) only in the transition state for catalytic transesterification, which is stabilized by adjacent binding of the leaving nucleoside (U) group. | + | The line below this paragraph, {{ABSTRACT_PUBMED_10029539}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 10029539 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_10029539}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| | [[Category: Hydrolase/rna]] | | [[Category: Hydrolase/rna]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Apr 30 13:51:58 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:05:36 2008'' |
Revision as of 15:05, 30 June 2008
Template:STRUCTURE 1b2m
THREE-DIMENSIONAL STRUCTURE OF RIBONULCEASE T1 COMPLEXED WITH AN ISOSTERIC PHOSPHONATE ANALOGUE OF GPU: ALTERNATE SUBSTRATE BINDING MODES AND CATALYSIS.
Template:ABSTRACT PUBMED 10029539
About this Structure
1B2M is a Single protein structure of sequence from Aspergillus oryzae. Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of ribonuclease T1 complexed with an isosteric phosphonate substrate analogue of GpU: alternate substrate binding modes and catalysis., Arni RK, Watanabe L, Ward RJ, Kreitman RJ, Kumar K, Walz FG Jr, Biochemistry. 1999 Feb 23;38(8):2452-61. PMID:10029539
Page seeded by OCA on Mon Jun 30 18:05:36 2008
