Part:BBa_K2963009

capB*CA - encoding poly-γ-glutamic acid synthetase

The gene cluster capB*CA encode an multi-enzyme complex on cell membrane. This multi-enzyme complex is composed of capB*;capC and capA. capB catalyzes poly-γ-glutamic acid（γ-PGA） synthesis．And capC links CapB and CapA on the membrane. While CapA transports γ-PGA outside the cell.In our project, we use the this part to biosynthesize γ-PGA.

Usage and Biology

The BCA genes from Bacillus sp., encoding a polyglutamate synthetase located on the cell membrane, is capable of polymerizing glutamic acid to form poly-γ-glutamic acid. In Bacillus licheniformis, BCA are called capBCA.This part is used for producing L-glutamate-rich γ-PGA.

Characterization

We used NMR to detect γ-PGA and HPLC to analyze L- glutamate ratio of γ-PGA. The results showed we have successfully produced L-glutamate-rich γ-PGA.

By the NMR detection of the fermentation product, the specific hydrogen peaks a, b, and c on the γ-amide bond on the γ-polyglutamic acid could be detected at the corresponding time points. It was indicated that the synthetase capB*CA genes of Bacillus licheniformis heterologously expressed in Corynebacterium glutamicum, and the target product γ-polyglutamic acid was successfully produced.

We used HPLC to detect the L-glutamate monomer ratio of the γ-PGA we have produced. The results show that the L-glutamic acid monomer ratio reaches more than 90%. This part is working and we have produced L-glutamate-rich γ-PGA.