Small things matter – for example, an amino acid can completely change the architecture of the cell. Researchers from the Universities of Göttingen and Warwick have examined the structure and mechanics of the cell’s main cytoskeleton component: a protein called actin. Actin is present in all living cells and fulfills a number of important functions – from muscle contraction to cell signaling and cell shape. This protein comes in two different variants, known as „isoforms“ and called gamma-actin and beta-actin. The difference between the two proteins is tiny, just a few amino acids varying in only a part of the molecule. Yet, this small change has major effects on the cell. In nature, only mixtures of the two isoforms usually occur. In their study, the researchers separated the two isoforms and analyzed them individually. The results were published in the journal Nature Communications.
The researchers examined the behavior of filament networks, focusing particularly on the unique properties of each isoform. They used specialized techniques that allowed them to assess the mechanics and dynamics of research models of cytoskeletal networks, drawing on expertise in biophysics in Göttingen and bioengineering in Warwick.
The results suggest that gamma-actin preferably forms rigid networks near the cell tip, whereas beta-actin preferably forms parallel bundles with a distinct organizational pattern. This difference is likely due to the stronger interaction of gamma-actin with certain types of positively charged ions, making its networks stiffer than those formed by beta-actin.
Our findings are compelling as they open new avenues for understanding the complex dynamics of protein networks within cells.
– Professor Andreas Janshoff, Institute of Physical Chemistry, University of Göttingen
The research enhances scientists‘ understanding of fundamental cellular processes by shedding light on specific biological functions of actin. This will be particularly relevant for processes involving cellular mechanics, such as cell growth, division, and maturation in tissues.
„The implications of these discoveries extend to the broader field of cell biology and offer insights that could impact many research and application areas, including developmental biology,“ adds Janshoff.
Nietmann, P., et al. (2023). Cytosolic actin isoforms form networks with different rheological properties indicating specific biological function. Nature Communications. doi.org/10.1038/s41467-023-43653-w