Researchers
from the University of Wisconsin-Madison (WI, USA) have developed a new way to
use CRISPR, this time as a potential method for reducing antibiotic resistance.
By targeting the genes most effected by existing antibiotics, it is possible to
determine how best to improve the drugs or how to develop new ones.
“What
we need to do is to figure out new weaknesses in these bacteria,” commented
system developer Jason Peters to
Biotechnqiues.
Traditionally,
the CRISPR system is used for gene editing, cutting DNA at the target gene and
making edits while the cell repairs the damage. In comparison, this new method,
known as Mobile-CRISPRi, works by binding to DNA and blocking other proteins
from gaining access and activating transcription, thereby reducing gene
expression and protein synthesis.
CRISPRi
is a defanged form of CRISPR that has been engineered to be unable to cut DNA
due to a catalytically inactive Cas9 protein. To make it mobile, the team
utilized the process of conjugation, a kind of bacterial sex where bacteria
link up and exchange DNA. This allowed the CRSIPRi to be transferred from an E. coli model into the disease-causing
species being studied. These included Pseudomonas,
Salmonella, Staphylococcus and Listeria,
among others.
“You
basically mix the bacteria together and it happens,” Peters commented about
conjugation; “It doesn’t get much easier than that.”
The
results, recently published in Nature Microbiology, showed that when the amount
of protein that is targeted by the antibiotic is reduced, the bacteria becomes
much more sensitive to the drug at a lower concentration.
When
discussing the meaning of his technique, Peters stated: “What that means is
that you can now do studies on how antibiotics work directly in these
pathogens. That could give us a better clue about how these drugs work in the
different organisms and potentially what we can do to make them better.”
Manipulating
genes in established cultures of lab bacteria such as E. coli is relatively
simple, the problem comes when dealing with bacteria recently isolated from
their previous environment. The Mobile-CRISPRi system could be easily
transferred and open doors for understanding how bacteria colonize.
Peters
is offering the use of the new system to other labs, allowing other researchers
to study the germs of their choice.
“So
now it’s going to be completely available to the community,” said Peters. “Now
this gives people a path forward.”
Posted by Dr. Tim Sandle,
Pharmaceutical Microbiology