jejuni and other strains are currently under development and may soon provide glycoproteins with control over the specific glycoform that is required in E. The humanized glycosylation machinery adapted from C. These strains have been developed by transplanting and adapting the N-glycosylation system found in Campylobacter jejuni, which glycosylates similarly to the eukaryotic glycosylation machinery ( Wacker et al., 2002). coli strains can be used that are capable of glycosylating proteins. If, for example, glycosylation of a recombinant protein is required, specialized E. coli-mediated expression offers, several strategies have been developed to introduce mammalian protein modifications. Moreover, eukaryotic and mammalian cell systems are prone to contamination, often require special growth media and glycosylation systems must be frequently bypassed or disabled in order to produce humanized therapeutic proteins without introducing extra factors that could induce immunogenicity ( Hermeling et al., 2004 Kruszewska et al., 2008). coli is fast growing and suitable for industrial scale fermentation ( Huang et al., 2012). coli protein expression is in general cheaper, more susceptible to genetic modifications, and versatile with regard to mutant library development. Although the majority of therapeutic proteins are produced in eukaryotic and mammalian cell systems, E. Proteins of therapeutic significance, such as antibodies, enzymes and cytokines, commonly carry PTMs and disulfide bonds and often require proteolytic maturation to attain their correctly folded active conformations. coli-produced therapeutic proteins, although sensitive methods for their detection and removal exist ( Lopes et al., 2010). Lipopolysaccharide contaminations can also be troublesome for E. In addition, correct disulfide bond formation can be cumbersome. This prokaryotic workhorse however is not able to incorporate most eukaryotic post-translational modifications (PTMs), such as ubiquitination, glycosylation and phosphorylation, nor is it capable of other eukaryotic maturation processes, and proteolytic protein maturation. coli is suitable for large scale (industrial) production of many proteins. coli is the protein production workhorse of many scientists as E. Introducing Modifications in Escherichia.

Alanine codon