The concentration of the low weight extracellular molecules which facilitate quorum sensing is proportional to the size of the bacterial population. A small population produces a low concentration of sensing molecules, while a large population produces a high concentration of sensing molecules. These molecules are responsible for information exchange and inducing gene expression among bacterial populations.
Acyl homoserine lactones are present mainly in Gram negative bacteria and are in control of their own synthesis. There is a lot of diversity in this group, with different bacteria species being able to produce unique lactones; however, some bacteria species produce the same lactones. The head group consists of the homoserine lactone and is conserved among all types of lactones; the tail goup is the acyl function group and is a variable region that determines the specificity of the receptor.
Oligopeptide molecules are present mainly in Gram positive bacteria. Their synthesis is dependent on ribosomes and their peptides can be modified.
Pseudomonas quinolone signal is a quorum sensing molecule specific to the Psuedomonas species. High concentrations of these molecules are produced. They are transported via membrane vesicles.
Auto inducer two is a quorum sensing molecule used by many Gram negative bacteria to facilitate communication between different species.
Image sources:
Oligopeptide and Auto inducer two: http://www.grin.com/en/doc/264621/biological-nanofactories-altering-cellular-response-via-localized-synthesis
Psuedomonas quinolone signal: http://www.sciencedirect.com/science/article/pii/S0968000411001605
Oligopeptides, also known as small peptides, are bioactive peptides composed of 2-10 amino acid residues linked by peptide bonds. Numerous studies have shown that proteins are eventually absorbed in the form of oligopeptides and amino acids, Peptide Drug Discovery
ReplyDelete