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223d
From Proteopedia
(New page: 200px<br /><applet load="223d" size="350" color="white" frame="true" align="right" spinBox="true" caption="223d, resolution 1.700Å" /> '''DIRECT OBSERVATION ...) |
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==Overview== | ==Overview== | ||
| - | The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]- | + | The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]- [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it can form stable hydrogen-bonded base-pairs with either guanine or adenine. To investigate the geometric properties of pairing with guanine in a DNA double helix, the structure of d(CGCGPG)2 has been determined by single crystal X-ray analysis. The oligonucleotide crystallised as a left-handed Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ with 51 water molecules included in the final model converged at R = 0.179 (Rw = 0.159) for 2798 reflections (F > 2 sigma (F)) in the range 8 A to 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different: Watson-Crick and wobble types separately illustrate both cytosine-like and thymine-like behaviour. The result suggests that mutagenesis experiments involving P and other analogues which display pronounced base-pairing ambivalence can be used to examine the structural basis of substrate discrimination by polymerases that is essential to accurate genetic replication. |
==About this Structure== | ==About this Structure== | ||
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Direct observation of two base-pairing modes of a cytosine-thymine analogue with guanine in a DNA Z-form duplex: significance for base analogue mutagenesis., Moore MH, Van Meervelt L, Salisbury SA, Lin PK, Brown DM, J Mol Biol. 1995 Sep 1;251(5):665-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7666418 7666418] | Direct observation of two base-pairing modes of a cytosine-thymine analogue with guanine in a DNA Z-form duplex: significance for base analogue mutagenesis., Moore MH, Van Meervelt L, Salisbury SA, Lin PK, Brown DM, J Mol Biol. 1995 Sep 1;251(5):665-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7666418 7666418] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Brown, D | + | [[Category: Brown, D M.]] |
| - | [[Category: Lin, P | + | [[Category: Lin, P Kong Thoo.]] |
| - | [[Category: Meervelt, L | + | [[Category: Meervelt, L Van.]] |
| - | [[Category: Moore, M | + | [[Category: Moore, M H.]] |
| - | [[Category: Salisbury, S | + | [[Category: Salisbury, S A.]] |
[[Category: double helix]] | [[Category: double helix]] | ||
[[Category: modified]] | [[Category: modified]] | ||
[[Category: z-dna]] | [[Category: z-dna]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:21:14 2008'' |
Revision as of 14:21, 21 February 2008
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DIRECT OBSERVATION OF TWO BASE-PAIRING MODES OF A CYTOSINE-THYMINE ANALOGUE WITH GUANINE IN A DNA Z-FORM DUPLEX: SIGNIFICANCE FOR BASE ANALOGUE MUTAGENESIS
Overview
The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]- [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it can form stable hydrogen-bonded base-pairs with either guanine or adenine. To investigate the geometric properties of pairing with guanine in a DNA double helix, the structure of d(CGCGPG)2 has been determined by single crystal X-ray analysis. The oligonucleotide crystallised as a left-handed Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ with 51 water molecules included in the final model converged at R = 0.179 (Rw = 0.159) for 2798 reflections (F > 2 sigma (F)) in the range 8 A to 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different: Watson-Crick and wobble types separately illustrate both cytosine-like and thymine-like behaviour. The result suggests that mutagenesis experiments involving P and other analogues which display pronounced base-pairing ambivalence can be used to examine the structural basis of substrate discrimination by polymerases that is essential to accurate genetic replication.
About this Structure
223D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Direct observation of two base-pairing modes of a cytosine-thymine analogue with guanine in a DNA Z-form duplex: significance for base analogue mutagenesis., Moore MH, Van Meervelt L, Salisbury SA, Lin PK, Brown DM, J Mol Biol. 1995 Sep 1;251(5):665-73. PMID:7666418
Page seeded by OCA on Thu Feb 21 16:21:14 2008
