Moselio Schaechter

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November 08, 2012

Talmudic Question #92

Does DNA do anything other than serve as a repository for genetic information?


I haven't started to look this up yet, but what role does DNA (or RNAs) have in pH balance in the cell and as a sink for ions? All those phosphate groups must have a significant buffering capacity on a microscale. At this year's Canadian society of microbiology meeting, there was an excellent talk about the chelating ability of DNA; implicated in its effectiveness as NETs (the previously mentioned neutrophilic extracellular DNA). Could cells be balancing out their salts with their DNA?

Kill bacteria in eukaryotic systems.

Cell Death Differ. 2011 Apr;18(4):581-8.
Dying for a cause: NETosis, mechanisms behind an antimicrobial cell death modality.


Neutrophil extracellular traps (NETs) are chromatin structures loaded with antimicrobial molecules. They can trap and kill various bacterial, fungal and protozoal pathogens, and their release is one of the first lines of defense against pathogens. In vivo, NETs are released during a form of pathogen-induced cell death, which was recently named NETosis. Ex vivo, both dead and viable neutrophils can be stimulated to release NETs composed of either nuclear or mitochondrial chromatin, respectively. In certain pathological conditions, NETs are associated with severe tissue damage or certain auto-immune diseases. This review describes the recent progress made in the identification of the mechanisms involved in NETosis and discusses its interplay with autophagy and apoptosis.

Elio, what is your opinion on the subject?!

Mark, indeed. A great paper from 2002. Nice and short and to the point! A real MPU (minimal publishable unit), which is great for educators to show their students...

One could argue that DNA is also a signalling molecule, particularly for eukaryotic innate immune responses.

Not to mention its role in neutrophil extracellular traps to wrap up microbes!

There are hints in the large literature that has established DNA as a structural and diffusion-limiting part of some biofilms that it may be produced or released in a manner different from simple cell lysis, and may not have the same composition as the genomic DNA (see DOI: 10.1111/j.1574-6968.2006.00361.x).

Also, DNA is a carbon and energy source (as well as providing P and N) for some microbes. The uptake of polymeric DNA as a substrate for growth is possibly involved in the development of natural competence (for example, DOI: 10.1128/​AEM.02674-06).

DNA can act as a conductor for electrons. Given the recent work on bacterial nano-wires, are there any reports of conjugative pili or other DNA structures used to transfer electrons?

oh. and when bacteria are sending plasmids to each other, DNA is also acting as a signal molecule, on some level. no?

of course! its a central bulletin board for keeping track of what's going on in the cell:

1) the cell 'knows' what state it is in by the collection of proteins bonded to the control sequences for each gene

2) transcription complexes look at this bulletin board to see which genes should be expressed at any given time

It also serves as a tempting explanatory gadget, satisfying our essentialistic beliefs about causality, intentions and the living. Of which, it is seems, quite unaware.

Isn't there some pretty nice work showing DNA to be a structural component in some biofilms?

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