Conclusion In order to detect the changes in M. loti between GS-4997 in vitro free-living and symbiotic conditions, we performed proteome analysis of M. loti. We used our LC-MS/MS system, equipped with a long monolithic silica capillary column, to successfully identify 1,658 proteins without bacteroid isolation and prefractionation. This analytical system opens up a new horizon
for symbiotic proteome analysis from small amounts of unpurified crude biological samples. The protein profile indicated some interesting and unexpected results associated with the cell surface structure and metabolism, in accordance with the external environment of each condition (Figure 5). The data set revealed that M. loti under the symbiotic condition simplifies the components of the cell surface, such as flagellum, pilus, and cell wall. In addition, we found that M. loti under the symbiotic condition provided not only a nitrogen source but also FPP, which is a source of secondary metabolism. Our data should be helpful in carrying out
detailed studies on the change of these 2 conditions Apoptosis inhibitor of rhizobia. Figure 5 Schematic representation of the lifestyle under the symbiotic condition compared to the free-living condition. The illustration shows the changes in the lifestyles of M. loti: the lifestyle model under the (a) free-living and (b) symbiotic conditions. The central carbon metabolic pathway is essential under both conditions. Under the symbiotic condition, nitrogen is fixed by electrons from the TCA cycle or other energy metabolism and is provided to the host Trichostatin A mouse legume or used for amino acid biosynthesis. Moreover, the flagellum and pilus are lost, and the cell wall, which is mainly composed of peptidoglycan, may become thin or disappear. In contrast, FPP is synthesized to provide to the host legume. Under the free-living condition, LPS is secreted extracellularly as a nod factor to infect the host legume. Methods Strains and growth conditions M. loti MAFF303099 was cultured
in tryptone-yeast extract (TY) Branched chain aminotransferase medium  at 28°C. Cells were harvested in the early stationary phase for 72 h. Cells were subjected to sample preparation in the free-living condition. For the symbiotic condition, L. japonicus MG-20 Miyakojima  seeds were sterilized, germinated, and inoculated with M. loti and grown in MM1  medium at 25°C with a 16-h light/8-h dark cycle. Root nodules from several plants were harvested at 7 weeks post-inoculation. Nodules from 3 independently grown pools of plants were collected and processed in parallel. Nodules were frozen with liquid nitrogen, homogenized with an ice-cold mortar, and subjected to sample preparation. Sample preparation Collected cells were resuspended with 500 μL of lysis buffer (2% (w/v) 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate, 10 mM dithiothreitol, 1% (v/v) protease inhibitor cocktail (Sigma-Aldrich, St.