AlteredN-glycan composition impacts flagella mediated adhesion inChlamydomonas reinhardtii

For the unicellular alga Chlamydomonas reinhardtii , the presence of N -glycosylated proteins on the surface of two flagella is crucial for both cell-cell interaction during mating and flagellar surface adhesion. It is unknown whether the composition of N -glycans attached to respective proteins is important for these processes. To this end, we examined several C. reinhardtii insertional mutants and a CRIPSR/Cas9 knockout mutant of xylosyltransferase 1A, all possessing altered N -glycan compositions. Taking advantage of atomic force microscopy and micropipette force measurements, our data revealed that reduction in N -glycan complexity impedes the adhesion force required for binding the flagella to surfaces. In addition, polystyrene bead binding and transport is impaired. Notably, assembly, Intraflagellar Transport and FMG-1B transport into flagella are not affected by altered N -glycosylation. Thus, we conclude that proper N -glycosylation of flagellar proteins is crucial for adhering C. reinhardtii cells onto surfaces, indicating that N -glycans mediate surface adhesion via direct surface contact.