These slides were created from the information provided by the article titled "Peptide nucleic acid restores colistin susceptibility through modulation of MCR-1 expression in Escherichia coli" by Mariana Jaramillo Gómez.

1. Presented by Mariana Jaramillo Gómez
Third semester.
Universidad Pontificia Bolivariana.
Molecular Biology.

2. Colistin.
• Colistin is a cyclic polypeptide belonging to the
group of polymyxins, which due to
its properties has the capacity to alter the
permeability of the wall of sensitive gram-
negative bacteria, which have an external layer
made up of lipopo-lysaccharide (LPS).
• The polymyxins lead to the cellular death of the
bacteria by the electrostatic attraction exercised
between the positive charge of the amino
groups and the phosphate and carboxylate
anions that compose the lipopolysaccharide
layer.

3. MCR-1
• Gene confers plasmid-mediated resistance
to colistin.
• The gene is found in no less than ten
species of the Enterobacteriaceae:
Escherichia coli, Salmonella, Klebsiella
pneumoniae, and others.
• The mechanism of resistance of the MCR
gene is a phosphatidylethanolamine
transferase.

4. Objectives.
• To evaluate the associations among promoter
sequence variation, mcr-1 expression, host
factors and levels of colistin resistance and to
propose antisense agents such as peptide nucleic
acids (PNAs) targeting mcr-1 as a tool to restore
colistin susceptibility through modulation of
MCR-1 expression in Escherichia coli.

5. Métodos-CMI
• La concentración mínima
inhibitoria es la
concentración más baja
(en μg/ml) de un antibiótico
que inhibe el crecimiento de
una determinada cepa
bacteriana.
• Este método se interpreta de
tres formas: Sensible,
Intermedia o Resistente.

6. Métodos-PCR
cuantitativa en tiempo
real (qRT-PCR)
• la PCR es una técnica basada en la
amplificación enzimática de una
secuencia específica, y en tiempo
real hace alución a la capacidad de
realizar esa amplificación al mismo
tiempo que se hace la
cuantificación de la secuencia.

7. Métodos-Construcción del plasmido.
• Es una técnica de biología
molecular que tiene como
objetivo hacer muchas copias
idénticas de un fragmento de
AND, como un gen, el cual se
inserta primero en un fragmento
circular de AND llamado plásmido,
luego se introduce en bacterias
para que de como resultado la
copia del AND que contienen.

8. Western blotting
• Es una técnica analítica para
detectar proteínas específicas
en una determinada muestra de
tejido homogeneizado o
extracto.

9. Resultados.

10. Resultados.

11. Resultados.

12. Resultados.

13. Discussion.
AUTOR Results of your research. Comparation with the results of
this investigation
Huang B, He Y, Ma X et
al
One report showed that mcr-1 promoter variation
significantly affected promoter activity and mcr-1
expression, but that mcr-1 expression did not correlate
with colistin resistance levels in E. coli and Klebsiella
pneumoniae
Wang Q, Li Z, Lin J et al. Another study showed that promoter activity and colistin
resistance levels were determined by mcr-1 promoter
variation in E. coli
Daly SM, Sturge CR,
Felder-Scott CF et al
As a result of chromosomal differences, different copy
numbers of the mcr-1 plasmids carrying mcr-1 and other
unknown factors, neither the MCR-1-PPMO reported by
Daly et al.

14. Conclussions.
• The study noted the importance of MIC in determining
which type of antibiotic is most effective in inhibiting the
proliferation of a bacterial strain, which will increase the
chances of success of treatment. In addition, to combat the
resistance that certain bacteria are generating to certain
medicines.
• Once again, we see how E. coli lends itself as a model
organism in laboratory tests, because thanks to its growth
rate, few nutritional requirements and its highly flexible
genome, is very useful for generating new research in the
field of molecular and genetic biology.
• Because of their ability to reproduce independently of
DNA, plasmids have been a staple of the evolution of
bacteria and therefore have a key role in the spread of
antibiotic resistance genes.