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The distinction between Gram-positive and Gram-negative bacteria is based upon the Gram staining method, that reflects the bacterial wall physical properties. However, this classification involves also a large number of differences between them. For example, the endospore formation usually occurs in Gram-positive bacteria and also the quorum sensing mechanism is different.

So what are those differences? Which of them are due to the cell wall thickness and membrane(s) composition and which instead to evolutionary divergences?

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here's a partial answer... biology.stackexchange.com/questions/7118/… –  shigeta Jun 10 '13 at 15:10
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I didn't know there were distinct differences between gram-positive and gram-negative bacteria when it came to quorum sensing, but it seems as though there are:

In gram negative bacteria, acyl-homoserine lactone type molecules serve as the main signalling molecules while lipid, peptide, and amino acid based signalling molecules infrequently serve as signalling molecules. Furthermore, in gram-negative bacteria, there is one well conserved mechanism for controlling quorum response. Gram-positive bacteria, on the other hand, use peptides or modified peptides as the primary means of signaling; and also differing from gram-negative bacteria, there are several different mechanisms found within the class which are used to gain quorum responses.

Source.

In G+ bacteria, the two main quorum sensing mechanisms are apparently as follows:

  1. Two-component signal transduction, in which the peptide signal works by binding to a sensor protein, histidine kinase, located in the cell membrane of the bacterium. The activation of the histidine kinase leads to phosphorylation of response-regulating protein, and interaction with another regulatory protein facilitates transcriptional activation.

  2. Internalization, in which the signal molecules are transported into the responder cell to interact with intracellular effectors.

G- bacteria on the other hand, synthesize autoinducers, effector molecules that can diffuse freely through the cell membrane and trigger cell response when a certain concentration threshold is reached. I do not know how or if these differences are related to cell wall structure.

When it comes to endospore formation, all I know of the difference between the two is that this is by far most common in gram-positive bacteria.

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