Legumes represent an important source of food protein for human nutrition and animal feeding. Therefore, sustainable production of legume crops is an issue of a global importance. For this, high efficiency of legume-rhizobial symbiosis is a pre-requisite. The efficiency of this mutual association, in turn, strongly depends on precise regulation of interactions between the plant and rhizobial partners. Although the underlying mechanisms are well-characterized, the knowledge on the architecture of regulatory pathways and probable effectors is still incomplete. Indeed, in our recent analysis of the common bean noodle proteome, multiple age-related glycation hot spots were identified [1]. Thus, it can be possible, that advanced glycation end products (AGEs) are involved in regulation of age-related changes in nodules. Therefore, here we address the effects of synthetic AGEs (free amino acids and AGE-containing peptides), supplemented to cultured rhizobia (Rhizobium leguminosarum). The primary growth inhibition assays were performed with methylglyoxal-derived hydroimidazolone 1 (Nδ-(5-methyl-4-oxo-5-hydroimidazolinone-2-yl)-L-ornithine, MG-H1), which was reported to be pro-inflammatory in mammalian test-systems. However, both amino acid and peptide were non-toxic in rhizobial culture in the range of concentrations 1 – 500 μmol/L. On another hand, application of 25 μmol/L MG-H1 increased the growth rate of the bacterial culture during the first five hours. To address this effect in more detail, total protein fraction was isolated from the cells, harvested before and after 5 or 18 h after supplementation of AGEs. The proteins were digested and analyzed by nanoLC-ESI-LIT-Orbitrap-MS in a data-dependent acquisition (DDA) mode. Database search was based on the SEQUEST algorithm, whereas quantitative differences were characterized by the label-free strategy.
[1] Matamoros M.A., Kim A., Peñuelas M., Ihling C., Griesser E., Hoffmann R., Fedorova M., Frolov A., Becana M., Protein carbonylation and glycation in legume nodules.// 2018, Plant Phys. V.177(4), PP. 1510-1528.
The research was supported by the Russian Foundation for Basic Research (RFBR, project 18-016-00190).