Asparagine-linked protein glycosylation: from eukaryotic to prokaryotic systems

Abstract

Asparagine-linked protein glycosylation is a prevalent protein modification reaction in eukaryotic systems. This process involves the co-translational transfer of a pre-assembled tetradecasaccharide from a dolichyl-pyrophosphate donor to the asparagine side chain of nascent proteins at the endoplasmic reticulum (ER) membrane. Recently, the first such system of N-linked glycosylation was discovered in the Gram-negative bacterium, Campylobacter jejuni. Glycosylation in this organism involves the transfer of a heptasaccharide from an undecaprenyl-pyrophosphate donor to the asparagine side chain of proteins at the bacterial periplasmic membrane. Here we provide a detailed comparison of the machinery involved in the N-linked glycosylation systems of eukaryotic organisms, exemplified by the yeast Saccharomyces cerevisiae, with that of the bacterial system in C. jejuni. The two systems display significant similarities and the relative simplicity of the bacterial glycosylation process could provide a model system that can be used to decipher the complex eukaryotic glycosylation machinery.

Conservation of the PTEN catalytic motif in the bacterial undecaprenyl pyrophosphate phosphatase, BacA/UppP

“…eukaryotes, bacteria and archaea (Calo et al, 2010;Helenius & Aebi, 2004;Jones et al, 2009;Larkin & Imperiali, 2011;Nothaft & Szymanski, 2010;Schwarz & Aebi, 2011;Weerapana & Imperiali, 2006). Monophosphate lipid carriers are also used in the synthesis of bacterial cell envelope polymers such as peptidoglycan, lipopolysaccharides and teichoic acids (Bouhss et al, 2008;Cantagrel & Lefeber, 2011;de Kruijff et al, 2008;Lovering et al, 2012;Reusch & Salton, 1984;Swoboda et al, 2010).…”

In Vitro Activity of Neisseria meningitidis PglL O-Oligosaccharyltransferase with Diverse Synthetic Lipid Donors and a UDP-activated Sugar

“…Alternatively, glycosylation may occur via an en bloc mechanism, in which the sugars are assembled onto a lipid carrier before being transferred to acceptor proteins through the activity of specialized non-Leloir glycosyltransferases collectively known as "oligosaccharyltransferases" (OTases). 4 The en bloc mechanism for N-glycosylation is a fundamental process in eukaryotes and archaea (5)(6)(7). However, in bacteria, this mechanism is only employed by species within the ⑀-proteobacteria, such as Campylobacter jejuni, and the ␦-proteobacteria, particularly within the genus Desulfovibrio (8,9).…”

A filamentous phage display system for N‐linked glycoproteins

“…We anticipate that the reduced complexity of bacteria will allow for detailed genetic characterization of this important mechanism, which is currently very challenging to study in eukaryotes owing to the essential nature of glycosylation in these cells. Yet, because of the striking similarities between the prokaryotic and eukaryotic N-glycosylation pathways, 6,34 lessons learned in glycosylation-competent E. coli may help to shed light on similar steps in the eukaryotic process. Moreover, the combination of a phage display system for N-linked glycosylation with the extensive toolkit available for metabolic pathway engineering and protein engineering promises to make E. coli one of the premier hosts for glycoengineering.…”