Highly stable triple helix formation by homopyrimidine (l)-acyclic threoninol nucleic acids with single stranded DNA and RNA

2015 ◽  
Vol 13 (8) ◽  
pp. 2366-2374 ◽  
Author(s):  
Vipin Kumar ◽  
Venkitasamy Kesavan ◽  
Kurt V. Gothelf

Homopyrimidine acyclic (l)-threoninol nucleic acid (aTNA) was synthesized and found to form highly stable (l)-aTNA–DNA–(l)-aTNA and (l)-aTNA–RNA–(l)-aTNA triple helical structures.

2000 ◽  
Vol 267 (12) ◽  
pp. 3592-3603 ◽  
Author(s):  
Andrei V. Maksimenko ◽  
Evgueny M. Volkov ◽  
Jean-Rémi Bertrand ◽  
Horea Porumb ◽  
Claude Malvy ◽  
...  

2019 ◽  
Vol 47 (14) ◽  
pp. 7213-7222 ◽  
Author(s):  
Charlotte N Kunkler ◽  
Jacob P Hulewicz ◽  
Sarah C Hickman ◽  
Matthew C Wang ◽  
Phillip J McCown ◽  
...  

AbstractRecent studies suggest noncoding RNAs interact with genomic DNA, forming an RNA•DNA–DNA triple helix that regulates gene expression. However, base triplet composition of pyrimidine motif RNA•DNA–DNA triple helices is not well understood beyond the canonical U•A–T and C•G–C base triplets. Using native gel-shift assays, the relative stability of 16 different base triplets at a single position, Z•X–Y (where Z = C, U, A, G and X–Y = A–T, G–C, T–A, C–G), in an RNA•DNA–DNA triple helix was determined. The canonical U•A–T and C•G–C base triplets were the most stable, while three non-canonical base triplets completely disrupted triple-helix formation. We further show that our RNA•DNA–DNA triple helix can tolerate up to two consecutive non-canonical A•G–C base triplets. Additionally, the RNA third strand must be at least 19 nucleotides to form an RNA•DNA–DNA triple helix but increasing the length to 27 nucleotides does not increase stability. The relative stability of 16 different base triplets in DNA•DNA–DNA and RNA•RNA–RNA triple helices was distinctly different from those in RNA•DNA–DNA triple helices, showing that base triplet stability depends on strand composition being DNA and/or RNA. Multiple factors influence the stability of triple helices, emphasizing the importance of experimentally validating formation of computationally predicted triple helices.


2005 ◽  
Vol 83 (10) ◽  
pp. 1731-1740 ◽  
Author(s):  
Robert HE Hudson ◽  
Filip Wojciechowski

We have investigated the incorporation of C6 derivatives of uracil into polypyrimidine peptide nucleic acid oligomers. Starting with uracil-6-carboxylic acid (orotic acid), a peptide nucleic acid monomer compatible with Fmoc-based synthesis was prepared. This monomer then served as a convertible nucleobase whereupon treatment of the resin-bound methyl orotate containing hexamers with hydroxide or amines cleanly converted the ester to an orotic acid or orotamide-containing peptide nucleic acid. Peptide nucleic acid hexamers containing the C6-modified nucleobase hybridized to both poly(riboadenylic acid) and poly(deoxyriboadenylic acid) via triplex formation. Complexes formed with poly(riboadenylic acid) were more stable than those formed with poly(dexoyriboadenylic acid), as measured by temperature-dependent UV spectroscopy. However, both of these complexes were destabilized relative to the complexes formed by an unmodified peptide nucleic acid oligomers. Internal or doubly substituted hexamers are destabilized more strongly than a terminally substituted one, and the type of substitution (carboxamide, ester, carboxylic acid) affects the overall triplex stability. These results clearly show that incorporation of a C6-substituted uracil into polypyrimidine PNA is detrimental to triplex formation. We have also extended this chemistry to incorporate uracil-5-methylcarboxylate into a peptide nucleic acid hexamer. After on-resin conversion of the C5 ester to the 3-(N,N-dimethylamino)propylamide, significant stabilization of the triplex formed with poly(riboadenylic acid) was observed, which illustrates the compatibility of C5 substitution with peptide nucleic acid directed triple helix formation. Key words: peptide nucleic acid, triple helix, orotic acid, orotamide, PNA.


2020 ◽  
Author(s):  
Asem Alenaizan ◽  
Joshua L Barnett ◽  
Nicholas V Hud ◽  
C David Sherrill ◽  
Anton S Petrov

Abstract The helical structures of DNA and RNA were originally revealed by experimental data. Likewise, the development of programs for modeling these natural polymers was guided by known structures. These nucleic acid polymers represent only two members of a potentially vast class of polymers with similar structural features, but that differ from DNA and RNA in the backbone or nucleobases. Xeno nucleic acids (XNAs) incorporate alternative backbones that affect the conformational, chemical, and thermodynamic properties of XNAs. Given the vast chemical space of possible XNAs, computational modeling of alternative nucleic acids can accelerate the search for plausible nucleic acid analogs and guide their rational design. Additionally, a tool for the modeling of nucleic acids could help reveal what nucleic acid polymers may have existed before RNA in the early evolution of life. To aid the development of novel XNA polymers and the search for possible pre-RNA candidates, this article presents the proto-Nucleic Acid Builder (https://github.com/GT-NucleicAcids/pnab), an open-source program for modeling nucleic acid analogs with alternative backbones and nucleobases. The torsion-driven conformation search procedure implemented here predicts structures with good accuracy compared to experimental structures, and correctly demonstrates the correlation between the helical structure and the backbone conformation in DNA and RNA.


1991 ◽  
Vol 113 (20) ◽  
pp. 7775-7777 ◽  
Author(s):  
Carine Giovannangeli ◽  
Therese Montenay-Garestier ◽  
Michel Rougee ◽  
Marcel Chassignol ◽  
Nguyen T. Thuong ◽  
...  

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