In-silico evaluation of ‘Mirror Repeats’ In HIV Genome

The repetitive sequences played an important role in the characterization of both prokaryotic & eukaryotic organisms. Various different patterns of repetitive sequences have also been identified in organisms. Among all the repeat sequences. Mirror Repeats (MR`s) play an important role in various types of neurological disorders. These MR`s have also been reported for structure determination of genomes, triplex DNA formation & various other genome functions. We have followed a distinguished method referred to as FPCB (FASTA PARALLEL COMPLEMENT BLAST) for the identification of MR`s. The above said method used to identify MR’s in both types of HIV viruses (HIV-1 & HIV-2). Present investigation reported that MR’s are frequently distributed in all the regions of the genomes of both types. As a result, 232 & 248 total numbers of MR`s identified in both the HIV-1 & HIV-2 genome respectively. In addition, it was also revealed that the majority of the identified sequences are imperfect. The maximum length of MR`s in HIV-1 is of 47 nucleotides (NTD`s), however in case of HIV-2, it is of 49 nucleotides (NTD`s). Present investigation will be helpful for further development of a link between mirror repeats and host genome, which will be a new trend to block the viral integration as well as pathogenicity.

Sequence Recognition by a Pseudorotational Cycle of Sugar Puckers: A Base Pair Switching Model via N-E Sugar Pucker Conversion for Homologous Recombination

A triplex DNA model bound to a helical filament of homologous recombination protein, such as Escherichia coli RecA, is presented. This model suggests that a function of the nucleoprotein filament could be at least partly attributed to the lowering of transition energy of duplex DNA structure having the E-type sugar puckers. Key events during homologous recombination such as sequence recognition, base pair switching and elongation/contraction of the helical pitch may correlate with the pseudo-rotation angle of sugar puckers along the N-, E-, S- and W-types. A conformational change of sugar puckers during the reaction is resolved into two motions by introducing a pair of parameters, μ1 and ν3, which defines a swing orientation of bases and a torsional angle of phosphate backbones, respectively.

pH-Responsive DNA Motif: From Rational Design to Analytical Applications

pH-responsive DNA motifs have attracted substantial attention attributed to their high designability and versatility of DNA chemistry. Such DNA motifs typically exploit DNA secondary structures that exhibit pH response properties because of the presence of specific protonation sites. In this review, we briefly summarized second structure-based pH-responsive DNA motifs, including triplex DNA, i-motif, and A+-C mismatch base pair-based DNA devices. Finally, the challenges and prospects of pH-responsive DNA motifs are also discussed.

Selectivity of a bromoacridine-containing fluorophore for triplex DNA

Fluorophore 1,8-naphthilamide was linked to 2-bromoacridine through an ethylenediamine spacer using a succinct synthetic route to give a bromoacridine-linked, bifunctional fluorophore conjugate for the detection of triplex DNA. Acridine is well known to intercalate into duplex DNA whereas introduction of a bulky bromine atom at position C2 redirects specificity for triplex over duplex DNA. In this work, photoelectron transfer assay was used to demonstrate that the synthesised 2-bromoacridine-linked fluorophore conjugate had good selectivity for the representative triplex DNA target sequence d(T*A.T)20 compared with double-stranded d(T.A)20, single-stranded dT20 or d(G/A)19 DNA sequences. Graphic abstract

A catalytic triplex DNAzyme for porphyrin metalation

Trihydroxyphenyl porphyrin (POH3) was designed to specifically bind with a triplex DNA by a resultant turn-on fluorescence response. This ensemble can be developed into a catalytic triplex DNAzyme towards porphyrin...