By Sachi Lagwankar

Quorum Sensing

• process of bacterial cells “talking” to each other in order to be informed of the population density in its vicinity

• Bacteria can only act on the host cell when the impact of the process is at its maximum

• Mutants (change signaling patterns) use QS in order to attack.

• used commonly when starting infections in organisms.

What is QS?

Oligopeptide signal

Gram positive bacteria

Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone)

Gram negative bacteria

Autoinducers

• Chemical molecular signals

• gram negative bacteria: acylated homoserine lactones (AHL)

• Gram positive bacteria: oligo-peptides

What are Autoinducers?

• only way mutants know how to communicate

• scientists are trying to find a way to inhibit this so that mutants don't take over host cells.

Importance

• sticky layer of polymers that microorganisms secrete and stick to one another on all surfaces

• Controlled by AI 2

• Common in people, though they can cause illness

Biofilm

• Multidrug-Resistant Tuberculosis (MDR TB) is resistant to the two most commonly used antibiotics for TB- isoniazid (INH) and rifampin (RIF). This means that people who get TB are unable to be cured using these antimicrobials. 

•  “tame” bacteria, and not to kill them

Antibiotics

Paul Williams: generate a drug that can

search and take out bacteria and that will

prevent them from doing damage to the host

cell.

Option 1

Geoff Watts: stop bacteria from sending

signals, eliminate infections

Option 2

Peter Greenberg: encourage mutants to

dominate fatal wounds and they do better

and do not use quorum sensing and are less

virulent

Option 3

Steve Diggle: experiment- add mutants to the

potential fatal wounds already infected with the

virulent bacteria, those wounds actually did better.

Option 4

Alan Smyth: a natural quorum sensing inhibitor is

to use extracts of plants like garlic extract

Option 5

• the immune system take over the virus before it attacks the host cell and infects it.

• when mutants send signal, cell makes protein to be released out of cell

• confuse the mutant into thinking there are more of it.

• when the mutant attacks, the human cell will use its immune system to kill the mutant.

Design Goal

Design:

Truth Table

Pseudomonas aeruginosa

Using Design Illness

1 0 10 0 01 1 0

• idea of how quorum sensing can be used to

prevent illness in humans.

• this is designed to help humans and

prevent them from getting illnesses.

Ethics

• http://www.bbc.co.uk/programmes/p01bhlvr

• http://rstb.royalsocietypublishing.org/content/362/1483/1241.full

• http://downloads.bbc.co.uk/podcasts/worldservice/discovery/discovery_20130708-2000a.mp3

• http://www.ncbi.nlm.nih.gov/pubmed/23142623

• https://www.youtube.com/watch?v=2R4XHRufoWI

• http://jb.asm.org/content/187/13/4372

• http://en.wikipedia.org/wiki/Autoinducer

• http://www.perspectivesinmedicine.net/content/2/11/a012427.full

• http://www.ncbi.nlm.nih.gov/pubmed/11544353

• https://www.bio.cmu.edu/courses/03441/TermPapers/99TermPapers/Quorum/table.htm

• http://www.ncbi.nlm.nih.gov/pubmed/11018124

• http://www.niaid.nih.gov/topics/tuberculosis/understanding/whatistb/pages/tbdefinitions.aspx

• http://mpkb.org/home/pathogenesis/microbiota/biofilm

Sources