Spatial Models of Piezoproteins and Networks of Protein-Protein Interactions in Trichoplax Animals (Placozoa)

Abstract

The marine free-living organism Trichoplax (phylum Placozoa) resembles the unicellular amoeba in shape and type of movement. Trichoplax diverged from the main evolutionary tree in the Neoproterozoic Era and is one of the simplest models of a multicellular animal, as well as a strong example of the ensemble of interacting cells in an organism during its development and movement. Two orthologs of mouse Piezo1 protein (6B3R) were found in two Trichoplax haplotypes H1 and H2 as a result of a search for similar sequences in the NCBI databases. Spatial models of the corresponding proteins, XP_002112008.1 and RDD46920.1, were created based on the structural alignment using a 6KG7 (mouse Piezo2) template. The analysis of domain structures was performed, and a limited graph of protein‒protein interactions of the hypothetical mechanosensor XP_002112008.1 was constructed. The possibility of signal transduction from the mechanoreceptor to membrane complexes, cytoplasm and cell nucleus was shown. It is assumed that mechanosensory receptors of Trichoplax are involved in the perception of force stimuli between neighboring cells and the environment. Based on the obtained data, we propose to use the primitive Trichoplax organism as the simplest multicellular model for mechanical and morphogenetic movements.