New study reveals secrets of the glycocalyx in cilia!

New study reveals secrets of the glycocalyx in cilia!

In a current study conducted by Prof. Dr. Michael Hippler and Dr. Lara Hoepfner, the complex structure of the glycocalyx of cilia is illuminated. Cilia are hair-like projections on biological cells that play a central role in locomotion and signal perception. The research focused on the glycocalyx of green algaeChlamydomonas reinhardtii, which consists of sugar-rich proteins, also called glycoproteins, and crucially regulates the ability of cells to adhere to surfaces. This has been widely published in the journal Advanced Science, as the University of Münster reports that...

As part of this investigation, the research team mapped the structure of the glycocalyx and discovered that the main components, the glycoproteins FMG1B and an unknown variant FMG1A, have biochemical similarities to mucins also found in mammals. These results shed new light on the role of the glycocalyx.

Glycoproteins and their function

The study shows that removing the glycoproteins resulted in an increase in the stickiness of the cilia while still allowing the cells to move smoothly on surfaces. This suggests that the glycoproteins are not directly responsible for adhesion and sliding, but rather form a protective layer that regulates adhesion.

The technologies used included cryogenic electron tomography, electron microscopy, fluorescence microscopy and mass spectrometry. The research was also financially supported by the European Research Council (Horizon 2020), the German Research Foundation and other institutions.

Additional findings on the cell wall ofChlamydomonas reinhardtii

Additional studies deepen our knowledge of the cell wall components of green algae. Extracted cell wall components were obtained using chaotropic agents and reconstructed after dialysis. A particular challenge was to preserve the minor components of the cell wall. More lenient protocols were used to preserve structurally important components.

Both scanning and transmission electron microscopy (SEM and TEM) showed intact microalgae and the characteristic layering of the cell wall. Surprisingly, the cell membrane and internal organelles remained intact after extraction, indicating the effectiveness of the chosen method.

Flow cytometry revealed that approximately 80% of cells remained alive and metabolically active after wall extraction. This is a crucial indication of the resistance of the cells to the procedures carried out. In addition, no significant differences were found between cell wall extracts and intact cells in NMR analysis.

Glycan and amino acid composition

Chemical analysis provided a comprehensive glycan and amino acid composition profile. What is particularly notable is the high content of mannose and N-acetylglucosamine in the cell wall. The amino acid profile shows high levels of alanine, glutamine and glutamate. The identification of new groups of low molecular weight glycoproteins (LWGPs) shows that they account for 80% of the amino acid content.

Cell wall dynamics show that glycans are less mobile than proteins, suggesting a semi-mobile structure. The spatial segregation of glycans and proteins suggests that glycosylated proteins play at the interface between the two groups.

In summary, both the glycocalyx and the cell wall ofChlamydomonas reinhardtiihave structural features that show parallels to plants, particularly with regard to the amino acid composition of the cell wall proteins. These findings could not only improve our understanding of this type of algae, but also the fundamentals of cell biology.