Bacterial cytoplasm has glass-like properties

[Pythagorean]

The physical nature of the bacterial cytoplasm is poorly understood even though it determines cytoplasmic dynamics and hence cellular physiology and behavior. Through single-particle tracking of protein filaments, plasmids, storage granules, and foreign particles of different sizes, we find that the bacterial cytoplasm displays properties that are characteristic of glass-forming liquids and changes from liquid-like to solid-like in a component size-dependent fashion. As a result, the motion of cytoplasmic components becomes disproportionally constrained with increasing size. Remarkably, cellular metabolism fluidizes the cytoplasm, allowing larger components to escape their local environment and explore larger regions of the cytoplasm. Consequently, cytoplasmic fluidity and dynamics dramatically change as cells shift between metabolically active and dormant states in response to fluctuating environments. Our findings provide insight into bacterial dormancy and have broad implications to our understanding of bacterial physiology, as the glassy behavior of the cytoplasm impacts all intracellular processes involving large components.

http://www.cell.com/abstract/S0092-8674(13)01479-7

 

[Mike H]

Meant to thank you for pointing this paper out a while back, but I've been distracted lately.

I'd always been a bit frustrated with the "slightly salty lipid-enclosed bag of enzymes" approach that many go with for simplicity, but I think things are starting to turn around on this point. People are appreciating the role of membrane organization and sequestration, and of macromolecular crowding, and so on.

:thumbs:

 

[gravenewworld]

The physical nature of the cellular cytoplasm also depends on the time scales one is observing with, which has been known for a while:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1300770/

 

[gravenewworld]

As it seems I'm the only person that specializes in glycobiology, one way that cells can modify the physical properties of their cytoskeleton through metabolism is through the all important O-glcnac modification (at least in mammalian cells), which has been known for a while:

http://www.jbc.org/content/275/38/29179.short

Talin, vaniculin, synapsins, and many proteins involved with regulation of tubulin and actin are modified by O-glcnac.

You could write an entire textbook on the O-glcnac modification and its importance to all of life, but long story short: the O-glcnac modification is one of the end products of glycolysis. In otherwords, both the O-glcnac modification as well as the massive amount of proteins that are O-glcnac modified (such as the many proteins involved in cytoskeletal organization and regulation) are absolutely linked to the metabolic states of cells.

You constantly read about the abnormal metabolic states in cancer with subsquently abberrant signaling cascades, how stem cells differentiate based on their metabolic states, and in this case, how the cytoplasm's physical properties are a function of metabolism. Well, one way to explain all of these observations is that glycolytic metabolism is inherently linked to the master control mechanism of the O-glcnac modification which differentially responds to environmental cues/stress.

It would be interesting to see if the bacteria they use is capable of the O-glcnac modification.