Searching for G-Quadruplex-Binding Proteins in Plants: New Insight into Possible G-Quadruplex Regulation

• Published in: BioTech
• Main Authors: Adriana Volná, Martin Bartas, Jakub Nezval, Vladimír Špunda, Petr Pečinka, Jiří Červeň
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Subjects: G-quadruplex-binding proteins; RGG motif; NIQI; G-quadruplex folding; G-quadruplex resolving; regulation of gene expression
• Online Access: https://www.mdpi.com/2673-6284/10/4/20

G-quadruplexes are four-stranded nucleic acid structures occurring in the genomes of all living organisms and viruses. It is increasingly evident that these structures play important molecular roles; generally, by modulating gene expression and overall genome integrity. For a long period, G-quadruplexes have been studied specifically in the context of human promoters, telomeres, and associated diseases (cancers, neurological disorders). Several of the proteins for binding G-quadruplexes are known, providing promising targets for influencing G-quadruplex-related processes in organisms. Nonetheless, in plants, only a small number of G-quadruplex binding proteins have been described to date. Thus, we aimed to bioinformatically inspect the available protein sequences to find the best protein candidates with the potential to bind G-quadruplexes. Two similar glycine and arginine-rich G-quadruplex-binding motifs were described in humans. The first is the so-called “RGG motif”-RRGDGRRRGGGGRGQGGRGRGGGFKG, and the second (which has been recently described) is known as the “NIQI motif”-RGRGRGRGGGSGGSGGRGRG. Using this general knowledge, we searched for plant proteins containing the above mentioned motifs, using two independent approaches (BLASTp and FIMO scanning), and revealed many proteins containing the G4-binding motif(s). Our research also revealed the core proteins involved in G4 folding and resolving in green plants, algae, and the key plant model organism, <i>Arabidopsis thaliana</i>. The discovered protein candidates were annotated using STRINGdb and sorted by their molecular and physiological roles in simple schemes. Our results point to the significant role of G4-binding proteins in the regulation of gene expression in plants.