A poly-gamma-glutamate synthetic system of Bacillus subtilis IFO 3336: Gene cloning and biochemical analysis of poly-gamma-glutamate produced by Escherichia coli clone cells

Three genes encoding a poly-gamma-glutamate synthetic system of Bacillus su btilis IFO 3336 (Bacillus natto) were cloned and expressed in Escherichia c oli. The E. coli clone produced poly-gamma-glutamate extracellularly. The g enes, newly designated as pgsBCA, were homologous with capBCA genes of Baci llus anthracis. All of pgsB, pgsC, and pgsA genes were essential for the po lymer production. Addition of Mn2+, instead of Mg2+, to the polymer-synthes is medium resulted in an increase in the polymer yield. Co-expression of gl utamate racemase gene in E. coli cells harboring pgsBCA genes increased bot h the polymer production and D-glutamate content in the polymer. The polyme r produced by the E. coli clone was higher in average molecular size than t hat produced by B. subtilis IFO 3336. (C) 1999 Academic Press.