Enhancing the yield of human erythropoietin in Aspergillus niger by introns and CRISPR-Cas9

Publication date: Available online 15 January 2020Source: Protein Expression and PurificationAuthor(s): Uriel Rojas-Sánchez, Alberto Cristian López-Calleja, Blanca E. Millán-Chiu, Francisco Fernández, Achim M. Loske, Miguel A. Gómez-LimAbstractAspergillus niger has been employed to produce heterologous proteins due to its high capacity for expression and secretion; nevertheless, expression levels of human proteins have been modest. We were interested in investigating whether A. niger can express and secret human erythropoietin (HuEPO) at high yields. Our strategy was to combine the presence of introns with CRISPR-Cas9 to increase the yield of the recombinant protein. The epo gene was codon-optimized and its expression driven by the PmbfA promoter. Another version of epo contained introns from the fructose-1,6-bisphosphatase (fbp) gene. Two recombinant clones, uME12 (no introns) and uME23 (with introns), were selected based on the resistance to the antibiotic and because they showed a protein profile different from that of the parental strain, as shown by SDS-PAGE. Expression of epo was confirmed by RT-PCR in both colonies but the recombinant EPO protein (rHUEPO) was detected by Western blot only in uME23. The rHuEPO yield from uME23 was estimated at about 1.8 mg L−1 by ELISA, demonstrating that the presence of introns resulted in higher yield, possibly by conferring more stability to mRNA. On the other hand, as part of our strategy we decided to inactivate in the...
Source: Protein Expression and Purification - Category: Biochemistry Source Type: research