b1,4-Galactosylation of plant N-glycans is a prerequisite for commercial production of certain biopharmaceuticals in plants. Two different types of galactosylated N-glycans have initially been reported in plants as the result of expression of human b1,4-galactosyltransferase 1 (GalT). Here we show that these differences are associated with differences at its N-terminus: the natural short variant of human GalT results in hybrid type N-glycans, whereas the long form generates bi-antennary complex type N-glycans. Furthermore, expression of non-mammalian, chicken and zebrafish GalT homologues with N-termini resembling the short human GalT N-terminus also induce hybrid type N-glycans. Providing both non-mammalian GalTs with a 13 amino acid N-terminal extension that distinguishes the two naturally occurring forms of human GalT, acted to increase the levels of biantennary galactosylated N-glycans when expressed in tobacco leaves. Replacement of the cytosolic tail and transmembrane domain of chicken and zebrafish GalTs with the corresponding region of rat a2,6-sialyltransferase yielded a gene whose expression enhanced the level of bi-antennary galactosylation even further.
- murine beta-1,4-galactosyltransferase
- beta 1,4-galactosyltransferase
- transgenic plants
Hesselink, T., Rouwendal, G. J. A., Henquet, M. G. L., Florack, D. E. A., Helsper, J. P. F. G., & Bosch, H. J. (2014). Expression of natural human b1,4-GalT1 variants and of non-mammalian homologues in plants leads to differences in galactosylation of N-glycans. Transgenic Research, 23(5), 717-728. https://doi.org/10.1007/s11248-014-9806-z