Disclosure of the differences of Mesorhizobium loti under the free-living and symbiotic conditions by comparative proteome analysis without bacteroid isolation

BMC Microbiology

Research Article

Yohei Tatsukami¹  Mami Nambu¹  Kouichi Kuroda¹  Mitsuyoshi Ueda²  Hironobu Morisaka² 

[1] Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, 606-8502, Sakyo-ku, Kyoto, Japan;Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, 606-8502, Sakyo-ku, Kyoto, Japan;Kyoto Industrial Science and Technology Innovation Center, 600-8813, Shimogyo-ku, Kyoto, Japan;

关键词: Mesorhizobium loti;    Lotus japonicus;    Symbiosis;    Proteome analysis;    Plant-microbe interaction;    Monolithic column;    Nitrogen fixation;    Rhizobase;    KEGG;   

DOI  :  10.1186/1471-2180-13-180

 received in 2013-03-21, accepted in 2013-07-26,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundRhizobia are symbiotic nitrogen-fixing soil bacteria that show a symbiotic relationship with their host legume. Rhizobia have 2 different physiological conditions: a free-living condition in soil, and a symbiotic nitrogen-fixing condition in the nodule. The lifestyle of rhizobia remains largely unknown, although genome and transcriptome analyses have been carried out. To clarify the lifestyle of bacteria, proteome analysis is necessary because the protein profile directly reflects in vivo reactions of the organisms. In proteome analysis, high separation performance is required to analyze complex biological samples. Therefore, we used a liquid chromatography-tandem mass spectrometry system, equipped with a long monolithic silica capillary column, which is superior to conventional columns. In this study, we compared the protein profile of Mesorhizobium loti MAFF303099 under free-living condition to that of symbiotic conditions by using small amounts of crude extracts.ResultWe identified 1,533 and 847 proteins for M. loti under free-living and symbiotic conditions, respectively. Pathway analysis by Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that many of the enzymes involved in the central carbon metabolic pathway were commonly detected under both conditions. The proteins encoded in the symbiosis island, the transmissible chromosomal region that includes the genes that are highly upregulated under the symbiotic condition, were uniquely detected under the symbiotic condition. The features of the symbiotic condition that have been reported by transcriptome analysis were confirmed at the protein level by proteome analysis. In addition, the genes of the proteins involved in cell surface structure were repressed under the symbiotic nitrogen-fixing condition. Furthermore, farnesyl pyrophosphate (FPP) was found to be biosynthesized only in rhizobia under the symbiotic condition.ConclusionThe obtained protein profile appeared to reflect the difference in phenotypes under the free-living and symbiotic conditions. In addition, KEGG pathway analysis revealed that the cell surface structure of rhizobia was largely different under each condition, and surprisingly, rhizobia might provided FPP to the host as a source of secondary metabolism. M. loti changed its metabolism and cell surface structure in accordance with the surrounding conditions.

【 授权许可】

Unknown   
© Tatsukami et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.