Microbials for the production of monoclonal antibodies and antibody fragments

New opportunities by synthetic biology for biopharmaceutical production in Pichia pastoris

Proteomic analysis of fatty-acylated proteins in mammalian cells with chemical reporters reveals S-acylation of histone H3 variants

The development of Pichia pastoris as a production platform for recombinant proteins has been a remarkable success story over the last three decades. Stable cheap production processes and the good protein secretion abilities were pacemakers of this development. However, limitations of protein folding, glycosylation or secretion have been identified quite early on. With the availability of genome sequences and the development of systems biology characterization in the last 5 years, remarkable success in strain improvement was achieved. Here, we focus on recent developments of characterization and improvement of P. pastoris production strains regarding protein folding, intracellular trafficking, glycosylation and proteolytic degradation.

Quo vadis? The challenges of recombinant protein folding and secretion in Pichia pastoris

Human milk proteins provide essential nutrition for growth and development, and support a number of vital developmental processes in the neonate. A complete understanding of the possible functions of human milk proteins has been limited by incomplete knowledge of the human milk proteome. In this report, we have analyzed the proteomes of whey from human transitional and mature milk using ion-exchange and SDS-PAGE based protein fractionation methods. With a larger-than-normal sample loading approach, we are able to largely extend human milk proteome to 976 proteins. Among them, 152 proteins are found to render significant regulatory changes between transitional milk and mature milk. We further found that immunoglobulins sIgA and IgM are more abundant in transitional milk, whereas IgG is more abundant in mature milk, suggesting a transformation in defense mechanism from newborns to young infants. Additionally, we report a more comprehensive view of a complement system and associated regulatory apparatus in human milk, demonstrating the presence and function of a system similar to that found in the circulation but prevailed by alternative pathway in complement activation. Proteins involved in various aspects of carbohydrate metabolism are also described, revealing either a transition in milk functionality to accommodate carbohydrate-rich secretions as lactation progresses, or a potentially novel way of looking at the metabolic state of the mammary tissue. Lately, a number of extracellular matrix (ECM) proteins are found to be in higher abundance in transitional milk and may be relevant to the development of infants' gastrointestinal tract in early life. In contrast, the ECM protein fibronectin and several of the actin cytoskeleton proteins that it regulates are more abundant in mature milk, which may indicate the important functional role for milk in regulating reactive oxygen species.

Temporal changes in milk proteomes reveal developing milk functions.

Yeast is capable of performing posttranslational modifications, such as N- or O-glycosylation. It has been demonstrated that N-glycans play critical biological roles in therapeutic glycoproteins by modulating pharmacokinetics and pharmacodynamics. However, N-glycan sites on recombinant glycoproteins produced in yeast can be underglycosylated, and hence, not completely occupied. Genomic homology analysis indicates that the Pichia pastoris oligosaccharyltransferase (OST) complex consists of multiple subunits, including OST1, OST2, OST3, OST4, OST5, OST6, STT3, SWP1, and WBP1. Monoclonal antibodies produced in P. pastoris show that N-glycan site occupancy ranges from 75–85 % and is affected mainly by the OST function, and in part, by process conditions. In this study, we demonstrate that N-glycan site occupancy of antibodies can be improved to greater than 99 %, comparable to that of antibodies produced in mammalian cells (CHO), by overexpressing Leishmania major STT3D (LmSTT3D) under the control of an inducible alcohol oxidase 1 (AOX1) promoter. N-glycan site occupancy of non-antibody glycoproteins such as recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) was also significantly improved, suggesting that LmSTT3D has broad substrate specificity. These results suggest that the glycosylation status of recombinant proteins can be improved by heterologous STT3 expression, which will allow for the customization of therapeutic protein profiles.

Improvement of N-glycan site occupancy of therapeutic glycoproteins produced in Pichia pastoris

The present invention is related to methods and for producing higher titers of recombinant protein in a modified yeast host cell, for example Pichia pastoris, wherein the modified yeast cell lacks vacuolar sorting activity or has decreased vacuolar sorting activity relative to an unmodified yeast host cell of the same species. In particular embodiments vacuolar sorting activity is reduced or eliminated by deletion or disruption of a gene encoding Vps10 or a Vps10 homolog. The invention is also related to the modified yeast cells which are modified in accordance with the methods disclosed herein.

Methods for the production of recombinant proteins with improved secretion efficiencies

Unfortunately, in the original article, the name of the author Meehl Meehl was given incorrectly. The correct name is Michael Meehl for which we correctly presented above.

/pdf/erratum-to-improvement-of-n-glycan-site-occupancy-of-168yhjbuad.pdf

Heping Lin

Papers

Improvement of N-glycan site occupancy of therapeutic glycoproteins produced in Pichia pastoris

Methods for the production of recombinant proteins with improved secretion efficiencies

Erratum to: Improvement of N-glycan site occupancy of therapeutic glycoproteins produced in Pichia pastoris

Pichia pastoris cell for the production of recombinant proteins with improved secretion efficiencies