Three-centre C—H...O hydrogen bonds in the DNA minor groove: analysis of oligonucleotide crystal structures

1999 ◽  
Vol 55 (12) ◽  
pp. 2005-2012 ◽  
Author(s):  
Anirban Ghosh ◽  
Manju Bansal

AA·TT and GA·TC dinucleotide steps in B-DNA-type oligomeric crystal structures and in protein-bound DNA fragments (solved using data with resolution <2.6 Å) show very small variations in their local dinucleotide geometries. A detailed analysis of these crystal structures reveals that in AA·TT and GA·TC steps the electropositive C2—H2 group of adenine is in very close proximity to the keto O atoms of both the pyrimidine bases in the antiparallel strand of the duplex structure, suggesting the possibility of intra-base pair as well as cross-strand inter-base pair C—H...O hydrogen bonds in the DNA minor groove. The C2—H2...O2 hydrogen bonds in the A·T base pairs could be a natural consequence of Watson–Crick pairing. However, the cross-strand interactions between the bases at the 3′-end of the AA·TT and GA·TC steps obviously arise owing to specific local geometry of these steps, since a majority of the H2...O2 distances in both data sets are considerably shorter than their values in the uniform fibre model (3.3 Å) and many are even smaller than the sum of the van der Waals radii. The analysis suggests that in addition to already documented features such as the large propeller twist of A·T base pairs and the hydration of the minor groove, these C2—H2...O2 cross-strand interactions may also play a role in the narrowing of the minor groove in A-tract regions of DNA and help explain the high structural rigidity and stability observed for poly(dA)·poly(dT).

2020 ◽  
Vol 48 (15) ◽  
pp. 8302-8319
Author(s):  
Małgorzata Katarzyna Cabaj ◽  
Paulina Maria Dominiak

Abstract We used the high resolution and accuracy of the Cambridge Structural Database (CSD) to provide detailed information regarding base pairing interactions of selected nucleobases. We searched for base pairs in which nucleobases interact with each other through two or more hydrogen bonds and form more or less planar structures. The investigated compounds were either free forms or derivatives of adenine, guanine, hypoxanthine, thymine, uracil and cytosine. We divided our findings into categories including types of pairs, protonation patterns and whether they are formed by free bases or substituted ones. We found base pair types that are exclusive to small molecule crystal structures, some that can be found only in RNA containing crystal structures and many that are native to both environments. With a few exceptions, nucleobase protonation generally followed a standard pattern governed by pKa values. The lengths of hydrogen bonds did not depend on whether the nucleobases forming a base pair were charged or not. The reasons why particular nucleobases formed base pairs in a certain way varied significantly.


2014 ◽  
Vol 70 (a1) ◽  
pp. C1378-C1378
Author(s):  
Hiroki Kanazawa ◽  
Jiro Kondo

Crystal structures of several functional non-coding RNAs, such as ribozymes, aptamers, ribosomes and tRNAs, have been reported so far. Unusual structural motifs and non-complementary base pairs are important for their functions. In the present study, we have determined a crystal structure of an unusual RNA duplex containing a strontium ion binding motif. A 19 mer RNA (5'-UUGUCGCUU[Br]CGAAAAAGUC-3') was chemical synthesized and purified by denaturing PAGE. Crystallizations were performed by the sitting-drop vapor diffusion method. The initial phase was solved by the SAD method. Atomic parameters were refined at a resolution of 3.0 Å. The 19 mer RNA forms an unusual antiparallel duplex. At both ends of the duplex, the Watson-Crick G=C and A-U and the Wobble GoU and AoC base pairs are formed. The Wobble C10oA14* pair is available only in acidic condition by protonation of N1 of A14* (* indicates residues of the opposite strand). Two hydrogen bonds, N1-H(A14*)...O2(C10) and N6-H(A14*)...N3(C10), are observed in the base pair. In the center of the duplex, two sheared G11oA13* and G11*oA13 base pairs are formed. The distance between two RNA chains becomes shorter by the GoA base pair and hydrogen bonds between the Watson-Crick edge of G11 and the phosphate group of A12*. Therefore, the central A12 residue cannot make a base pair, but it makes a stacking interaction with A12*. The A12 residue stacks also with A13 of the sheared GoA base pair. As a result, an A13-A12-A12*-A13* stacked column is formed at the minor groove of the duplex, and the G11 base of the sheared GoA base pair is inclined toward the minor groove. By taking such a unique structure, the RNA duplex has a Sr2+ ion binding pocket in the center. A hydrated Sr2+ ion binds to O6 and N7 of G11 and G11*. The Sr2+ ion is surrounded by four phosphate groups of two RNA chains. The Sr2+ ion is tightly captured by eight hydrogen bonds in total.


2020 ◽  
Vol 26 (20) ◽  
pp. 4539-4551 ◽  
Author(s):  
Abdelbasset A. Farahat ◽  
Pu Guo ◽  
Hadir Shoeib ◽  
Ananya Paul ◽  
David W. Boykin ◽  
...  

2016 ◽  
Vol 22 (43) ◽  
pp. 15404-15412 ◽  
Author(s):  
Pu Guo ◽  
Ananya Paul ◽  
Arvind Kumar ◽  
Abdelbasset A. Farahat ◽  
Dhiraj Kumar ◽  
...  

2020 ◽  
Vol 48 (20) ◽  
pp. 11322-11334
Author(s):  
Tomáš Bouchal ◽  
Ivo Durník ◽  
Viktor Illík ◽  
Kamila Réblová ◽  
Petr Kulhánek

Abstract Mismatch repair is a highly conserved cellular pathway responsible for repairing mismatched dsDNA. Errors are detected by the MutS enzyme, which most likely senses altered mechanical property of damaged dsDNA rather than a specific molecular pattern. While the curved shape of dsDNA in crystallographic MutS/DNA structures suggests the role of DNA bending, the theoretical support is not fully convincing. Here, we present a computational study focused on a base-pair opening into the minor groove, a specific base-pair motion observed upon interaction with MutS. Propensities for the opening were evaluated in terms of two base-pair parameters: Opening and Shear. We tested all possible base pairs in anti/anti, anti/syn and syn/anti orientations and found clear discrimination between mismatches and canonical base-pairs only for the opening into the minor groove. Besides, the discrimination gap was also confirmed in hotspot and coldspot sequences, indicating that the opening could play a more significant role in the mismatch recognition than previously recognized. Our findings can be helpful for a better understanding of sequence-dependent mutability. Further, detailed structural characterization of mismatches can serve for designing anti-cancer drugs targeting mismatched base pairs.


2017 ◽  
Vol 73 (6) ◽  
pp. 481-485 ◽  
Author(s):  
Marimuthu Mohana ◽  
Packianathan Thomas Muthiah ◽  
Colin D. McMillen

In solid-state engineering, cocrystallization is a strategy actively pursued for pharmaceuticals. Two 1:1 cocrystals of 5-fluorouracil (5FU; systematic name: 5-fluoro-1,3-dihydropyrimidine-2,4-dione), namely 5-fluorouracil–5-bromothiophene-2-carboxylic acid (1/1), C5H3BrO2S·C4H3FN2O2, (I), and 5-fluorouracil–thiophene-2-carboxylic acid (1/1), C4H3FN2O2·C5H4O2S, (II), have been synthesized and characterized by single-crystal X-ray diffraction studies. In both cocrystals, carboxylic acid molecules are linked through an acid–acid R 2 2(8) homosynthon (O—H...O) to form a carboxylic acid dimer and 5FU molecules are connected through two types of base pairs [homosynthon, R 2 2(8) motif] via a pair of N—H...O hydrogen bonds. The crystal structures are further stabilized by C—H...O interactions in (II) and C—Br...O interactions in (I). In both crystal structures, π–π stacking and C—F...π interactions are also observed.


Author(s):  
Alan R. Kennedy ◽  
Abedawn I. Khalaf ◽  
Fraser J. Scott ◽  
Colin J. Suckling

The title nitropyrrole-based compounds, C7H8N2O4, (I) (ethyl 4-nitro-1H-pyrrole-2-carboxylate), its derivative C12H14N2O4, (II) [ethyl 4-nitro-1-(4-pentynyl)-1H-pyrrole-2-carboxylate], C15H26N4O3, (III) {N-[3-(dimethyamino)propyl]-1-isopentyl-4-nitro-1H-pyrrole-2-carboxamide}, and C20H27N9O5, (IV) {1-(3-azidopropyl)-4-(1-methyl-4-nitro-1H-pyrrole-2-carboxamido)-N-[2-(morpholin-4-yl)ethyl]-1H-pyrrole-2-carboxamide}, are intermediates used in the synthesis of modified DNA minor-groove binders. In all four compounds, the nitro groups lie in the plane of the pyrrole ring. In compounds (I) and (II), the ester groups also lie in the plane of the pyrrole ring. In compound (III), both of the other substituents lie out of the plane of the pyrrole ring. In the case of compound (IV), the coplanarity extends to the second pyrrole ring and through both amide groups. In the crystals of all four compounds, layer-like structures are formed,viaa combination of N—H...O and C—H...O hydrogen bonds for (I), (III) and (IV), but by only C—H...O hydrogen bonds for (II).


2002 ◽  
Vol 67 (10) ◽  
pp. 1560-1578 ◽  
Author(s):  
Michal Hocek ◽  
Hana Dvořáková ◽  
Ivana Císařová

The title 1,2-bis(purin-6-yl)acetylenes, -diacetylenes, -ethylenes and -ethanes were prepared as covalent base-pair analogues starting from 6-ethynylpurines and 6-iodopurines by the Sonogashira cross-coupling or oxidative alkyne-dimerization reactions followed by hydrogenations. 6-[(1,3-Dimethyluracil-5-yl)ethynyl]purine (11) was prepared analogously and hydrogenated to the corresponding purine-pyrimidine conjugates linked via vinylene and ethylene linkers. Unlike the cytostatic bis(purin-6-yl)acetylenes and -diacetylenes, the purine-pyrimidine conjugates were inactive. Crystal structures of bis(purin-6-yl)acetylene 6a, -diacetylene 8a and -ethane 5a were determined by single-crystal X-ray diffraction.


2020 ◽  
Vol 22 (17) ◽  
pp. 9316-9321
Author(s):  
Kaicheng Wang ◽  
Lixia Yang ◽  
Shaomeng Wang ◽  
Lianghao Guo ◽  
Jialu Ma ◽  
...  

Intense terahertz radiation was applied to trigger transient proton transfer in DNA base pairs through quantum simulation.


1995 ◽  
Vol 73 (6) ◽  
pp. 878-884 ◽  
Author(s):  
Ding-Kwo Chang ◽  
Shu-Fang Cheng ◽  
Ting-Lin Chien

Molecular mechanics calculations were performed on the three structures of the complexes formed by the derivatives of Hoechst 33258 and dodecameric DNA duplex d(CGCGAATTCGCG)2. Formation and docking energies of these complexes were compared. It was found that the CG site that is 3′ to the central AATT region can be tolerated by the drugs. This is probably due to the presence of the bulky piperazine ring and, more pronouncedly, by alkylated analogues of the drug that prefer the wider minor groove formed by the GC base pair region of B-DNA. The argument of bulkiness of the piperazine moiety as the origin of enhancement of GC affinity is supported by detailed structural analysis of the intermolecular interface and widening of the DNA minor groove at the binding site. Implications of the results are discussed. Keywords: minor groove binder, docking energy, sequence specificity.


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