Abstract
BACKGROUND: Rhizobia 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. RESULT: We 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. CONCLUSION: The 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.
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Claims 11
Claim · model-written summary
1533 M. loti proteins were identified under free-living conditions.
- Taxon
- M. loti
Mesorhizobium lotie0 - Outcome
- proteinse0
- Value
- 1,533e0
- Qualifier
- free-livinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We identified 1,533 and 847 proteins for M. loti under free-living and symbiotic conditions, respectively.”
Claim · model-written summary
847 M. loti proteins were identified under symbiotic conditions.
- Taxon
- M. lotiMesorhizobium lotie0
- Outcome
- proteinse0
- Value
- 847e0
- Qualifier
- symbiotic conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We identified 1,533 and 847 proteins for M. loti under free-living and symbiotic conditions, respectively.”
Claim · model-written summary
Many central-carbon metabolic enzymes were detected in both conditions.
- Taxon
- Mesorhizobium lotiMesorhizobium lotit0
- Outcome
- enzymes involved in the central carbon metabolic pathwaye0
- Qualifier
- commonly detected under both conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Mesorhizobium loti”
Claim · model-written summary
Symbiosis-island proteins were uniquely detected under symbiotic conditions.
- Taxon
- Mesorhizobium lotiMesorhizobium lotit0
- Outcome
- proteins encoded in the symbiosis islande0
- Qualifier
- uniquely detected under the symbiotic conditione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Mesorhizobium loti”
Claim · model-written summary
Proteomics confirmed previously transcriptome-reported features of the symbiotic condition at protein level.
- Taxon
- Mesorhizobium lotiMesorhizobium lotit0
- Outcome
- features of the symbiotic conditione0
- Comparator
- transcriptome analysise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The features of the symbiotic condition that have been reported by transcriptome analysis were confirmed at the protein level by proteome analysis.”
t0“Mesorhizobium loti”
Claim · model-written summary
Genes encoding cell-surface-structure proteins were repressed under symbiotic nitrogen fixation.
- Taxon
- Mesorhizobium lotiMesorhizobium lotit0
- Outcome
- genes of the proteins involved in cell surface structuree0
- Direction
- repressede0
- Qualifier
- symbiotic nitrogen-fixing conditione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In addition, the genes of the proteins involved in cell surface structure were repressed under the symbiotic nitrogen-fixing condition.”
t0“Mesorhizobium loti”
Claim · model-written summary
FPP biosynthesis was found only in symbiotic rhizobia.
Verbatim
e0“Furthermore, farnesyl pyrophosphate (FPP) was found to be biosynthesized only in rhizobia under the symbiotic condition.”
Claim · model-written summary
The protein profile appeared to reflect phenotypic differences between free-living and symbiotic conditions.
- Taxon
- Mesorhizobium lotiMesorhizobium lotit0
- Outcome
- difference in phenotypese0
- Qualifier
- appearede0
- Comparator
- free-livinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The obtained protein profile appeared to reflect the difference in phenotypes under the free-living and symbiotic conditions.”
t0“Mesorhizobium loti”
Claim · model-written summary
KEGG analysis indicated rhizobial cell-surface structure differed substantially between conditions.
- Taxon
- rhizobiae0
- Outcome
- cell surface structure of rhizobiae0
- Qualifier
- largely different under each conditione0
Not reportedDirection
Verbatim
e0“KEGG pathway analysis revealed that the cell surface structure of rhizobia was largely different under each condition”
Claim · model-written summary
Rhizobia might provide FPP to the host as a secondary-metabolism source.
Verbatim
e0“rhizobia might provided FPP to the host as a source of secondary metabolism.”
Claim · model-written summary
M. loti changed metabolism and cell-surface structure according to surrounding conditions.
- Taxon
- M. lotiMesorhizobium lotie0
- Outcome
- metabolism and cell surface structuree0
- Qualifier
- in accordance with the surrounding conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“M. loti changed its metabolism and cell surface structure in accordance with the surrounding conditions.”