Post on 05-Jan-2016
Quorum Sensing and Biofilms
Bacteria constantly release signal molecules If cell density is not big enough nothing
happens Threshold density all bacteria
simultaneously carry out gene expression “Quorum Sensing” from counting as to take
a vote before acting
Quorum Sensing Basics
Acyl homoserine lactones (AHL molecules) Easy transport of molecules outside of cells
Gram Negative Bacteria
Precursor Oligopeptides Must be exported via active transport
proteins
Gram Positive Bacteria
Al-2 molecule is universal Produced by LuxS enzyme from dihydroxy
pentanedione substrate
Inter Species Communication
Microorganisms form layer with proteins, DNA and long chain sugars
Often pathogenic Concern for health and food industry
◦ Spoiled food◦ Biofilms in cystis fibrosis
Quorum sensing plays big role in the high cell density communication and virulence
Biofilms
Scientists are investigating varied bio-film formations and mutations that could help decrease formation
Looking at mutant luxS enzymes and other quorum sensing systems
Disrupt quorum sensingdisrupt biofilm formation and virulence
Biofilms Today
Ep-CAM Gene Silencing in
Craniopharyngiomas
Benign epithelial brain tumor common in children
Cannot spread but presses on vital structures
Can cause stunted growth, obesity, diabetes insipidus, and other morbidity
Hard to remove due to strong adherence to important structures
Often reoccurs
Background
Ep-CAM gene expression is highly over expressed
Produces Ep-CAM glycoprotein adhesion molecule
Is linked to tumor genesis and metastasis Makes tumor strongly adherent
Ep-CAM Glycoprotein
Craniopharyngioma
Radiotherapy◦ Kills healthy cells◦ High risk of second cancer in children and adolescents
Competing Technologies
Silencing Ep-CAM gene by inhibiting transcription through methylation of the promoter region
Design
Inducing Bacteria
Aerotolerant E.Coli bacteria engineered to produce invasin protein and produce m5c DNA methyltransferase enzymes on signal
Calcification material
Ep-CAM glycoproteinReceptor
Receptor
Invasin and m5c Production
m5c methyltransferase enzymes
Invasin proteins
Bacteria Produces
B-1 Integrin receptor
Invading Tumor Cells
Tumor cell
Invasin Proteins
Inside Cell
Ep-CAM promoter
M5c DNA methyltrasnferase enzymes
Inhibition of RNA Polymerase Binding
RNA Polymerase
Ep-CAM Transcription
Ep-CAM glycoprotein
Calcium deposits m5c methyltransferase production
0 0 0
0 1 0
1 0 0
1 1 1
AND Gate Truth Table
Methylated CpG Islands on Promoter
Ep-CAM Expression
0 1
1 0
Inverter Logic Gate Truth Table
No damage to healthy cells Easy to administer No radioactive material Helps surgeons remove tumor Decrease reoccurrence
Advantages
Ep-CAM promoter region specific methylation
Laboratory precaution while working with cells with invasin
Precautions to keep bacteria from evolving and reproducing out of control
Possible Problems
Testing on tissue culture and many other steps before reaching human testing
Similar system could be tweaked and developed for other cancers
Testing