G-quadruplex can potentially form on the long non-coding RNA of pseudogene REG1CP, which interacts with the FANCJ helicase. This interaction affects the transcription of the REG3A gene, which is associated with the progression of colon cancer. In the master's thesis, we proved that the selected sequence from the long non coding RNA REG1CP forms a G-quadruplex with three stacked G quartets. At room temperature, the oligonucleotide existed in two secondary forms, as a hairpin and a G quadruplex, which were in equilibrium. At the physiological temperature, this equilibrium shifted towards the formation of the G-quadruplex, indicating that the G quadruplex is more prevalent in vivo. We synthesized RNA oligonucleotides of different lengths from the lncRNA sequence. By substituting individual nucleotides, we obtained a sequence with well-separated resonances in the NMR spectrum. We determined its thermal stability and studied the 3D structure of the G quadruplex REG1CP with the help of different NMR spectroscopy experiments. With the CD spectroscopy, we found that the mentioned G quadruplex has a parallel topology. Additionally, we titrated the G-quadruplex with different peptides and monitored their interactions. The G-quadruplex REG1CP formed a complex with Rhau18 and Rhau23 peptides, while the interaction with the peptide from the FANCJ helicase was weaker.
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