Discovery of a single-subunit oligosaccharyltransferase that enables glycosylation of full-length IgG antibodies in .

Human immunoglobulin G (IgG) antibodies are one of the most important classes of biotherapeutic agents and undergo glycosylation at the conserved N297 site in the C2 domain, which is critical for IgG Fc effector functions and anti-inflammatory activity. Hence, technologies for producing authentically glycosylated IgGs are in high demand. While attempts to engineer for this purpose have been described, they have met limited success due in part to the lack of available oligosaccharyltransferase (OST) enzymes that can install linked glycans within the QYNST sequon of the IgG C2 domain.

Bacterial glycoengineering: Cell-based and cell-free routes for producing biopharmaceuticals with customized glycosylation.

Glycosylation plays a pivotal role in tuning the folding and function of proteins. Because most human therapeutic proteins are glycosylated, understanding and controlling glycosylation is important for the design, optimization, and manufacture of biopharmaceuticals. Unfortunately, natural eukaryotic glycosylation pathways are complex and often produce heterogeneous glycan patterns, making the production of glycoproteins with chemically precise and homogeneous glycan structures difficult.

Glycovaccinology: The design and engineering of carbohydrate-based vaccine components.

Vaccines remain one of the most important pillars in preventative medicine, providing protection against a wide array of diseases by inducing humoral and/or cellular immunity. Of the many possible candidate antigens for subunit vaccine development, carbohydrates are particularly appealing because of their ubiquitous presence on the surface of all living cells, viruses, and parasites as well as their known interactions with both innate and adaptive immune cells. Indeed, several licensed vaccines leverage bacterial cell-surface carbohydrates as antigens for inducing antigen-specific plasma cells secreting protective antibodies and the development of memory T and B cells.

Shotgun scanning glycomutagenesis: A simple and efficient strategy for constructing and characterizing neoglycoproteins.

As a common protein modification, asparagine-linked (linked) glycosylation has the capacity to greatly influence the biological and biophysical properties of proteins. However, the routine use of glycosylation as a strategy for engineering proteins with advantageous properties is limited by our inability to construct and screen large collections of glycoproteins for cataloguing the consequences of glycan installation. To address this challenge, we describe a combinatorial strategy termed shotgun scanning glycomutagenesis in which DNA libraries encoding all possible glycosylation site variants of a given protein are constructed and subsequently expressed in glycosylation-competent bacteria, thereby enabling rapid determination of glycosylatable sites in the protein.