Three distinct glycosylation pathways are involved in the decoration of Lactococcus lactis cell wall glycopolymers

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Theodorou, Ilias
Courtin, Pascal
Sadovskaya, Irina
Palussière, Simon
Fenaille, François
Mahony, Jennifer
Chapot-Chartier, Marie-Pierre
van Sinderen, Douwe
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American Society for Biochemistry and Molecular Biology
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Extra-cytoplasmic sugar decoration of glycopolymer components of the bacterial cell wall contributes to their structural diversity. Typically, the molecular mechanism that underpins such a decoration process involves a three-component glycosylation system (TGS) represented by an undecaprenyl-phosphate (Und-P) sugar-activating glycosyltransferase (Und-P GT), a flippase, and a polytopic glycosyltransferase (PolM GT) dedicated to attaching sugar residues to a specific glycopolymer. Here, using bioinformatic analyses, CRISPR-assisted recombineering, structural analysis of cell wall-associated polysaccharides (CWPS) through Maldi-Tof MS and methylation analysis, we report on three such systems in the bacterium Lactococcus lactis. On the basis of sequence similarities, we first identified three gene pairs, csdAB, csdCD, and csdEF, each encoding an Und-P GT and a PolM GT, as potential TGS component candidates. Our experimental results show that csdAB and csdCD are involved in Glc side chain addition on the CWPS components rhamnan and polysaccharide pellicle (PSP), respectively, whereas csdEF plays a role in galactosylation of lipoteichoic acid (LTA). We also identified a potential flippase encoded in the L. lactis genome (llnz_02975, cflA) and confirmed that it participates in the glycosylation of the three cell wall glycopolymers rhamnan, PSP, and LTA, thus indicating that its function is shared by the three TGSs. Finally, we observed that glucosylation of both rhamnan and PSP can increase resistance to bacteriophage predation and that LTA galactosylation alters L. lactis resistance to bacteriocin.
Lactic acid bacteria , Glycopolymer , Phage receptor , Lipoteichoic acid , LTA , Flippase , Peptidoglycan , Glycosylation , Genomics , Glycobiology , Bacteriophage , Cell wall , Glycosyltransferase
Theodorou, I., Courtin, P., Sadovskaya, I., Palussière, S., Fenaille, F., Mahony, J., Chapot-Chartier, M.P. and van Sinderen, D. (2020) ‘Three distinct glycosylation pathways are involved in the decoration of Lactococcus lactis cell wall glycopolymers’, Journal of Biological Chemistry. doi: 10.1074/jbc.RA119.010844