Listeria protein provides a CRISPR 'kill switch'

July 13, 2020

ITHACA, N.Y. - A single protein derived from a common strain of bacteria found in the soil will offer scientists a more precise way to edit RNA.

The protein, called AcrVIA1, can halt the CRISPR-Cas13 editing process, according to new research from Cornell, Rockefeller University and the Memorial Sloan Kettering Cancer Center published in the journal Science July 3.

"We're expanding our scientific toolbox to effectively use a CRISPR without causing side effects," said co-author Martin Wiedmann, Ph.D. '97, the Gellert Family Professor in Food Safety and director of Cornell's Food Safety Laboratory and Milk Quality Improvement Program. "Thanks to this bacterium, we're getting a chance to turn off and on our ability to make changes to RNA."

CRISPR, or the clustered regularly interspaced short palindromic repeats, is a laboratory mechanism that can act like microscopic scissors and precisely edit the genes contained in DNA. Among the half-dozen types of CRISPRs in use today, CRISPR-Cas13 can edit RNA, which until now had lacked a brake in the editing process.

Since SARS-CoV-2, the coronavirus that causes the COVID-19 disease, is an RNA virus, this new editing accessory may be useful to coronavirus researchers, the scientists said.

Lead author Alex Meeske, postdoctoral researcher in the lab of senior author Luciano Marraffini, professor at Rockefeller University, had suspected that a protein (bacteriophage) housed in Listeria could be useful for RNA editing.

At the start of this study, Meeske reached out to Wiedmann, a food safety expert, to obtain genetic bacterial samples from his food pathogen collection. Doctoral candidate in the Wiedmann laboratory Jingqiu Liao narrowed down the prospects from about 1,500 bacterial candidates to 62 strains.

The Wiedmann lab transferred those samples to Rockefeller, where intern Alice Cassel sequenced the 62 strains and isolated 20 candidate proteins.

One strain stood out: Listeria seeligeri, a harmless bacteria found everywhere in the soil. Unlike its fierce cousin - the foodborne pathogen L. monocytogenes - it does not cause human disease.

The Rockefeller scientists found that the protein AcrVIA1 - derived from L. seeligeri - instantly stopped the CRISPR editing process. "AcrVIA1 can be very useful in controlling application of Cas13. Anything that the Cas13 edits, this anti-CRISPR protein can shut off," Meeske said. "It's a 'kill switch' you can use during the CRISPR editing process, and it has become an additional tool we have at our disposal."

Wiedmann explained that scientists can now work on RNA problems with more exacting means. "This tool gives us more precision," he said.

The paper, "A Phage-Encoded Anti-CRISPR Enables Complete Evasion of Type VI-A CRISPR- 2 Cas Immunity," was co-written by senior author Dinshaw J. Patel and Ning Jia, both of Memorial Sloan Kettering, and Albina Kozlova of Rockefeller.
-end-


Cornell University

Related Protein Articles from Brightsurf:

The protein dress of a neuron
New method marks proteins and reveals the receptors in which neurons are dressed

Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.

Diets high in protein, particularly plant protein, linked to lower risk of death
Diets high in protein, particularly plant protein, are associated with a lower risk of death from any cause, finds an analysis of the latest evidence published by The BMJ today.

A new understanding of protein movement
A team of UD engineers has uncovered the role of surface diffusion in protein transport, which could aid biopharmaceutical processing.

A new biotinylation enzyme for analyzing protein-protein interactions
Proteins play roles by interacting with various other proteins. Therefore, interaction analysis is an indispensable technique for studying the function of proteins.

Substituting the next-best protein
Children born with Duchenne muscular dystrophy have a mutation in the X-chromosome gene that would normally code for dystrophin, a protein that provides structural integrity to skeletal muscles.

A direct protein-to-protein binding couples cell survival to cell proliferation
The regulators of apoptosis watch over cell replication and the decision to enter the cell cycle.

A protein that controls inflammation
A study by the research team of Prof. Geert van Loo (VIB-UGent Center for Inflammation Research) has unraveled a critical molecular mechanism behind autoimmune and inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis.

Resurrecting ancient protein partners reveals origin of protein regulation
After reconstructing the ancient forms of two cellular proteins, scientists discovered the earliest known instance of a complex form of protein regulation.

Sensing protein wellbeing
The folding state of the proteins in live cells often reflect the cell's general health.

Read More: Protein News and Protein Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.