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These decoys are typically composed of a G-rich sequence that can form a stable G-quadruplex structure and a short linker region that can be modified to optimize their properties. [116] When introduced to cancer cells the decoy can intercept associated transcription factors and bind them leading to the regulation of gene expression.
The nucleotides 1-3 and 25-27 with an additional C4-G23 form a duplex motif, and the sequence ranging from G5 to G20 folds into a G-quadruplex structure with four connection loops: T9-A10, T18-T19, G13-C14-A15 and a one-nucleotide loop (T6). In the core of G-quadruplex motif, two G-tetrad planes are formed by G5-G7-G12-G16 and G8-G11-G17-G20.
G-quadruplexes, also known as G4 DNA are secondary structures found in nucleic acids that are rich in guanine. [1] These structures are normally located at the telomeres (the ends of the chromosomes). The G-quadruplex can either be parallel or antiparallel depending on the loop configuration, which is a component of the structure.
In molecular biology, a guanine tetrad (also known as a G-tetrad or G-quartet) is a structure composed of four guanine bases in a square planar array. [ 1 ] [ 2 ] They most prominently contribute to the structure of G-quadruplexes , where their hydrogen bonding stabilizes the structure.
The G-quartet typically binds monovalent cations such as potassium, while other bases can bind numerous other ligands such as hypoxanthine in a U-U-C-U quadruplex. [ 17 ] Along with these functions, the G-quadruplex in the mRNA around the ribosome binding regions could serve as a regulator of gene expression in bacteria . [ 19 ]
An individual motif usually consists of only a few elements, e.g., the 'helix-turn-helix' motif which has just three. Note that, while the spatial sequence of elements may be identical in all instances of a motif, they may be encoded in any order within the underlying gene. In addition to secondary structural elements, protein structural motifs ...
DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of base pairs. DNA damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. [1]
It is possible that these sequence stretches form G-quadruplex like structures, which can suppress the expression of the related genes. The complementary cytosine rich sequences, on the other strand, may adopt another similar four stranded structure, the i-motif, stabilized by cytosine:cytosine non-canonical base pairs.