Finding out how the total electric charge inside the cells of different species affects the mobility of proteins would give us a better idea of how fast tasks can be carried out in cells. Schavemaker, Śmigiel et al. now show that protein surface charge matters a great deal in the gut microbe Escherichia coli. In these cells, negatively charged and neutral proteins move about rapidly whereas positively charged proteins move up to 100 times more slowly.
In the salt-loving microbe Haloferax volcanii the positive proteins move relatively fast, but still more slowly than negatively charged and neutral proteins. In all likelihood this is because the protein charges are shielded from each other by large amounts of small charged molecules (which come from salts) in the Hfx. volcanii cells.
Schavemaker, Śmigiel et al. suggest that positively charged proteins slow down because they bind to negatively charged ribosomes. Because ribosomes are found in all living cells, understanding how they affect how other proteins move around the cell has a wide range of possible applications. For example, biologists and biotechnologists often produce proteins in E. coli for convenient study. Yet very positively charged proteins may bind to ribosomes in E. coli, causing experiments to fail. Using cells that shield charges better, such as Hfx. volcanii or Lactococcus lactis, could solve this issue.
This digest was originally published at eLife \cite{1} and is reproduced under a CC BY 4.0 license.