Possible functions of the conserved peptide encoded by the RNA-precursor of miR-156a in plants of the family Brassicaceae

Recent studies have shown that the primary transcripts of some microRNA genes (pri-miRNAs) are able to express short proteins (peptides) ranging usually from 12-15 amino acid residues to around 30 residues in length. These peptides, called miPEPs, may participate in the regulation of transcription of their own pri-miRNAs. Using bioinformatic comparative analysis of pri-miRNA sequences in plant genomes, we previously discovered a new group of miPEPs (miPEP-156a), which is encoded by pri-miR156a in several dozen species from the Brassicaceae family. Exogenous peptides miPEP-156a can effectively penetrate plant seedlings through the root system and spread systemically to the leaves of young seedlings. At the same time, a moderate morphological effect is observed, which consists in accelerated growth of the main root of the seedling. In parallel, a positive effect is observed at the level of pri-miR156a expression. It is important that the effects at the morphological and molecular levels are seemingly related to the ability of the peptide to quickly transfer into the cell nuclei and bind to nuclear chromatin. In this work, the secondary structure of the peptide was also experimentally established, and changes in this structure in the complex with DNA were shown.