AUTHOR=Göritzer Kathrin , Goet Iris , Duric Stella , Maresch Daniel , Altmann Friedrich , Obinger Christian , Strasser Richard 

TITLE=Efficient N-Glycosylation of the Heavy Chain Tailpiece Promotes the Formation of Plant-Produced Dimeric IgA

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00346

DOI=10.3389/fchem.2020.00346

ISSN=2296-2646

ABSTRACT=<p>Production of monomeric IgA in mammalian cells and plant expression systems such as <italic>Nicotiana benthamiana</italic> is well-established and can be achieved by co-expression of the corresponding light and heavy chains. In contrast, the assembly of dimeric IgA requires the additional expression of the joining chain and remains challenging especially in plant-based systems. Here, we examined factors affecting the assembly and expression of HER2 binding dimeric IgA1 and IgA2m(2) variants transiently produced in <italic>N. benthamiana</italic>. While co-expression of the joining chain resulted in efficient formation of dimeric IgAs in HEK293F cells, a mixture of monomeric, dimeric and tetrameric variants was detected in plants. Mass-spectrometric analysis of site-specific glycosylation revealed that the <italic>N</italic>-glycan profile differed between monomeric and dimeric IgAs in the plant expression system. Co-expression of a single-subunit oligosaccharyltransferase from the protozoan <italic>Leishmania major</italic> in <italic>N. benthamiana</italic> increased the <italic>N</italic>-glycosylation occupancy at the C-terminal heavy chain tailpiece and changed the ratio of monomeric to dimeric IgAs. Our data demonstrate that <italic>N</italic>-glycosylation engineering is a suitable strategy to promote the formation of dimeric IgA variants in plants.</p>