Proteomic analysis of glycoside hydrolases involved in the ginsenoside biotransformation by Leifsonia sp. GAL45 isolated in ginseng soil

We isolated a bacterial strain from a soil of ginseng field which was capable of metabolizing ginsenosides. The strain was designated as Leifsonia sp. GAL45 based on its 16S rRNA gene sequences. The whole genome was sequenced and found to consist of about 4.3 Mbp with 4256 CDS. The genome contained a relatively high proportion of carbohydrate transport and metabolism-related genes (COG G), which included 65 glycoside hydrolases (GH)-coding genes. Proteomes obtained from cells induced with saponin mixture were analyzed by using LC-MS/MS. After both intracellular and extracellular proteomes were analyzed, a total of 1783 proteins were detected, covering 41.9% of the total number of CDS in the genome. 427 extracellular and 142 intracellular proteins were found to be induced with saponin. Proteins of COG V (defense mechanisms), COG L (replication, recombination and repair), COG J (translation, ribosomal structure and biogenesis), COG F (nucleotide transport and metabolism) and COG C (energy production and conversion) were up-regulated and those of COG P (inorganic ion transport and metabolism) and COG N (cell motility) were down-regulated. Among the 65 GHs identified in the genome of strain GAL45, 33 enzymes were detected by proteomic approach. Enzymes which were expressed in the presence of saponin were identified and are currently examined for the activities of ginsenoside biotransformation.