Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China
Institute for Plant Biology and Biotechnology, University of Münster, Münster, Germany
Longsheng Zhao
Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom; State Key Laboratory of Microbial Technology, and Marine Biotechnology Research Center, Shandong University, Qingdao, China
Antoine Girot
Max Planck Institute for Dynamics and Self-Organization (MPIDS), Göttingen, Germany
Marzieh Karimi
Max Planck Institute for Dynamics and Self-Organization (MPIDS), Göttingen, Germany
Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom; College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
Institute for Plant Biology and Biotechnology, University of Münster, Münster, Germany; Institute of Plant Science and Resources, Okayama University, Kurashiki, Japan
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. However, it is not known whether only the presence or also the composition of N-glycans attached to respective proteins is important for these processes. To this end, we tested several C. reinhardtii insertional mutants and a CRISPR/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. This results in impaired polystyrene bead binding and transport but not gliding of cells on solid surfaces. Notably, assembly, intraflagellar transport, and protein import 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.
