Chinese hamster ovary (CHO) cells are the preferred host cells for the production of complex recombinant therapeutic proteins. Adenine phosphoribosyltransferase (APRT) is a key enzyme in the purine biosynthesis step that catalyzes the condensation of adenine with phosphoribosylate to form adenosine phosphate AMP. In this study, the gene editing technique was used to knock out the aprt gene in CHO cells. Subsequently, the biological properties of APRT-KO CHO cell lines were investigated. A control vector expressed an enhanced green fluorescent protein (EGFP) and an attenuation vector (containing an aprt-attenuated expression cassette and EGFP) were constructed and transfected into APRT-deficient and wild-type CHO cells, respectively. The stable transfected cell pools were subcultured for 60 generations and the mean fluorescence intensity of EGFP in the recombinant CHO cells was detected by flow cytometry to analyze the EGFP expression stability. PCR amplification and sequencing showed that the aprt gene in CHO cell was successfully knocked out. The obtained APRT-deficient CHO cell line had no significant difference from the wild-type CHO cells in terms of cell morphology, growth, proliferation, and doubling time. The transient expression results indicated that compared with the wild-type CHO cells, the expression of EGFP in the APRT-deficient CHO cells transfected with the control vector and the attenuation vector increased by 42%±6% and 56%±9%, respectively. Especially, the EGFP expression levels in APRT-deficient cells transfected with the attenuation vector were significantly higher than those in wild-type CHO cells (P < 0.05). The findings suggest that the APRT-deficient CHO cell line can significantly improve the long-term expression stability of recombinant proteins. This may provide an effective cell engineering strategy for establishing an efficient and stable CHO cell expression system.
Adenine/metabolism* ; Adenine Nucleotides ; Adenine Phosphoribosyltransferase/genetics* ; Adenosine Monophosphate ; Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Recombinant Proteins/genetics*

OBJECTIVETo identify adenine phosphoribosyltransferases in Schistosoma japonicum and analyze their structural features.

METHODSBased on the accessible transcriptome and proteomic data, the S. japonicum adenine phosphoribosyl transferases were identified using bioinformatics approaches including bi-directional homology comparison, domain search and phylogenetic analysis. Homology modeling was also performed to describe the structural features of the proteins.

RESULTS AND CONCLUSIONTwo homologue sequences of adenine phosphoribosyltransferase were obtained from S. japonicum, and the EST abundance, physico-chemical properties and three-dimensional structures of them were also acquired.

Adenine Phosphoribosyltransferase ; chemistry ; genetics ; Animals ; Computational Biology ; methods ; Helminth Proteins ; chemistry ; genetics ; Isoenzymes ; chemistry ; genetics ; Models, Molecular ; Phylogeny ; Protein Conformation ; Schistosoma japonicum ; enzymology