H. Zhao, K. Blazanovic, Y. Choi, C. Bailey-Kellogg, and K.E. Griswold, "Gene and protein sequence optimization for high level production of fully active and aglycosylated lysostaphin in Pichia pastoris", Appl. Environ. Microbiol., 2014, 80:2746-2753. [pubmed]

Lysostaphin represents a promising therapeutic agent for the treatment of staphylococcal infections, in particular those of Methicillin-resistant Staphylococcus aureus (MRSA). However, conventional expression systems for the enzyme suffer from various limitations, and there remains a need for an efficient and cost-effective production process to facilitate clinical translation and development of non-medical applications. While Pichia pastoris is widely used for high level production of recombinant proteins, there are two major barriers to production of lysostaphin in this industrially relevant host: lack of expression from the wild type lysostaphin gene and aberrant glycosylation of the wild type protein sequence. The first barrier can be overcome with a synthetic gene incorporating improved codon usage and balanced A+T/G+C content; the second barrier can be overcome by disrupting an N-linked glycosylation sequon using a broadened choice of mutations that yield aglyscosylated and fully active lysostaphin. The optimized lysostaphin variants could be produced at approximately 500 mg/L in a small scale bioreactor, and 50% of that material could be recovered at high purity with a simple 2-step purification. It is anticipated that this novel high level expression system will bring down one of the major barriers to future development of biomedical, veterinary, and research applications of lysostaphin and its engineered variants.