Abstract
Two-demensional gel electrophoresis was used to identify differentially displayed proteins of Bradyrhizobium japonicum USDA110 in the symbiotic and non-symbiotic state. When proteome maps were compared and the characterization of bacteroid-specific proteins was performed by N-terminal amino acid sequencing and matrix-assisted desorption/ionization time-of-flight mass spectrometry peptide mass fingerprint analysis, putative identity was assigned to 61 bacteroid protein spots, including many metabolic proteins and ABC transporters as well as nitrogenase proteins like NifH.
Although the biosynthesis of amino acids in B.japonicum bacteroids is believed to be down-regulated, various proteins responsible for amino acid transport were detected, and the data is corresponding to the report that amino acid transporter is essential for maintaining nitrogen fixation activity in bacteroids of B.japonicum. This study shows that proteome analysis will be a useful tool for surveying genes contributing to rhizobial functions in symbiosis.
