Secretory Expression of Escherichia coli L-Asparaginase in Corynebacterium glutamicum.

L-Asparaginase is a potential therapeutic enzyme used in the treatment of acute lymphoblastic leukemia. It is also useful as a food processing aid. Hence, many studies have been conducted to develop and optimize production methods for L-asparaginase using various microbial hosts. In this study, a secretory expression route for L-asparaginase was developed using recombinant Corynebacterium glutamicum. Fourteen signal sequences were primarily mined and used to induce the secretion of Escherichia coli L-asparaginase II (AsnB) in C. glutamicum. The signal sequence ss2629 induced efficient secretion of AsnB, achieving a productivity of 25.4 mg/l in batch cultivation. The resulting Cg-AsnB in the culture supernatant was subsequently purified using anion exchange and size exclusion chromatography, resulting in an overall yield of >12.8 mg/l. Although the productivity and purification yield remained to be further improved, the overall biochemical and structural properties of purified Cg-AsnB were comparable to those of commercially available Ec-AsnB. Taken together, these results could provide an alternative platform for the secretory production of L-asparaginase using endotoxin-free C. glutamicum as a host.