Features of the formation of Аrg-X proteolytic system of cellular nuclei during germination of wheat seeds

Gulnar Vafina, Ruslan Ivanov and Nadegda Kalashnik

Abstract: The processes of assembly and disassembly of chromatin with the participation of the nuclear proteome are the most important part of the regulatory network that controls the movement of cells the on cell cycle. In this aspect, histones play an important role, since their synthesis is coordinated with DNA synthesis and any changes in their sequence or structure can lead to an effect on cellular metabolism. The aim of the work was to study the dynamics of the activity of Arg-X proteolysis in nonhistone and histone fractions of nuclear structures (nucleoplasm, chromatin, nuclear matrix) during germination of wheat seeds under conditions of deacetylation inhibition of nuclear proteins (sodium butyrate). Seeds were germinated in distilled water (control) and in 0.004 mM NaB (sodium butyrate). Cell nuclei were isolated from germs, cleared, and then nucleoplasm, chromatin, nuclear matrix were extracted by increasing ionic strength of solution. From isolated supramolecular structures, non-histone proteins were separated from histones by using ion exchange chromatography. The Arg-X proteolytic activity was assessed by cleavage of Arg-X bonds in the arginine-enriched protein protamine. The duration of mitosis phases under conditions of deacetylation inhibition of nuclear proteins was determined. It is shown that Arg-X proteolysis appears in the fractions of nonhistone proteins and core histones (H2A + H2B; H3 + H4), mainly in the H3 + H4 block at the level of chromatin tightly bound. In addition, the increasing in Arg-X proteolytic activity (24 h-48 h) coincides with the beginning of proliferative activity, which may be due to chromatin rearrangements in cells during germination of seeds. The presented results can be considered as one of the illustrations of a complex regulatory proteinase network formed in cell nuclei, which can participate in proteolytic processing of histones, thereby affecting chromatin reorganization.

Keywords: Arg-X proteolysis; cell nuclei; histones; sodium butyrate; Triticum aestivum L.

Date published: 2021-02-17