분자유전학실험실 (단국대학교 분자생물학과)



 이성욱 ( 2018-03-01 13:50:14 , Hit : 613
 Powerful enzyme could make CRISPR gene-editing more versatile

Nature

https://www.nature.com/articles/d41586-018-02540-x

NEWS · 28 February 2018

Revamped Cas9 protein could work on more sites in the genome, and with fewer unwanted effects.

Heidi Ledford

An enzyme modified in the laboratory could boost the utility of CRISPR–Cas9 gene editing by allowing researchers to tinker with more sites in the genome — while also reducing the risk of undesired changes.

These features could make the enzyme, called xCas9, a laboratory staple, says David Liu, a chemical biologist at the Broad Institute of Harvard and MIT in Cambridge, Massachusetts, who led the work. But it will need more testing before its full potential becomes clear, he adds. The study is published today in Nature1.

Since its introduction about five years ago, CRISPR–Cas9 gene editing has become a key tool in many biology laboratories around the world. The technique allows researchers to make changes to the genome at specific sites with much greater ease than previous methods, but it still has some frustrating limitations.

One is the need to have a specific DNA sequence, called a PAM sequence, next to the site to be modified. Different Cas9 enzymes found in nature require different PAM sequences. The Cas9 most commonly used in laboratories was isolated from the bacterium Streptococcus pyogenes, and its PAM allows researchers to target about one out of every sixteen sites in a genome.

That’s good enough for many applications: researchers who want to disable a gene, for example, can select many sites within that gene to edit. But PAMs can become restrictive when researchers are trying to make very specific changes, says biochemist Albert Jeltsch of the University of Stuttgart in Germany.

This could include researchers who are studying how particular DNA sequences, or chemical modifications to specific DNA letters, affect gene expression. “Relief from the PAM restriction is quite important,” says Jeltsch. “Some of these elements are quite small, and then the restriction can be quite relevant.”

Sharpening molecular scissors

To find a way around this, Liu and his colleagues harnessed a method that forced Cas9 to evolve rapidly in the laboratory, accumulating mutations that allowed it to cut next to a variety of PAM sites. Eventually, they ended up with xCas9, which can cut DNA at sites near a broad range of PAM sites and could target one-quarter of sites in a genome.

The team tested its enzyme on dozens of sites in the genome, and combined it with tools called base editors to allow it to swap one DNA letter for another. To Liu’s surprise, xCas9 was also less likely to cut at other sites in the genome than the standard laboratory enzyme.

The same approach could be used to alter other variants of the Cas9 enzyme, including the relatively small Cas9 proteins that some hope to use for gene therapy, says bioengineer Prashant Mali of the University of California, San Diego. Those proteins, he says, tend to have frustratingly restrictive PAM sequences.

Synthetic biologist Stanley Qi of Stanford University in California calls the work “dazzling”, and says his team is eager to try it in the laboratory. “I am amazed that the new Cas9 has both broader PAM recognition and higher specificity,” he says. “That’s amazing biology.”

References
Hu, J. H. et al. Nature http://dx.doi.org/10.1038/nature26155 (2018).







27   Nonviral CRISPR Delivery a Success  이성욱 2017/10/03 690
26   [미국] 2017년, 유전자가위 기술을 통한 네 가지 사건들  이성욱 2018/01/10 689
25   Scientists Doubt Results of CRISPR’d Embryos  이성욱 2017/09/02 680
24   Alcohol Boosts Cancer Risk by Damaging Stem Cell DNA  이성욱 2018/01/05 673
23   Shields Up for New Cancer Gene-Therapy Virus  이성욱 2018/02/01 672
22   작년 바이오산업 규모 8조8775억원, 투자 13.9% 늘어  이성욱 2017/12/13 668
21   FDA Approves First Gene Therapy for Inherited Disease  이성욱 2017/12/22 664
20   릴리 '시람자' 간암 말기 임상시험 성공  이성욱 2018/04/07 654
19   Giants of Circadian Biology Win Nobel Prize  이성욱 2017/10/03 652
18   Technique Adapted from CRISPR-Cas9 Corrects Mutation in Human Embryos  이성욱 2017/09/29 652
17   CRISPR/Cas9 Edits Epigenome with Therapeutic Efficiency  이성욱 2017/12/09 636
16   CRISPR-Cas9 Improved 10,000-Fold by Synthetic Nucleotides  이성욱 2018/04/17 624
  Powerful enzyme could make CRISPR gene-editing more versatile  이성욱 2018/03/01 613
14   CRISPR’s MAGESTIC Evolution Makes Gene Editing More Precise  이성욱 2018/05/08 591
13   Cause of CRISPR Failure Identified and Reversed  이성욱 2018/07/12 549
12   Spark Therapeutics shares rise on FDA approval of new gene therapy for blindness  이성욱 2017/12/20 535
11   CRISPR-Cas12a More Precise Than CRISPR-Cas9  이성욱 2018/08/07 532
10   Gene Therapy Ever More Common for Rare Disorders  이성욱 2018/05/30 524
9   [바이오토픽] 유전자를 침묵시키는 신약, 20년의 기다림 끝에 승인  이성욱 2018/08/13 519
8   Doubts arise again about CRISR'd human embryos  이성욱 2018/08/09 517

[이전 10개] [1]..[61][62] 63 [64]
 

Copyright 1999-2024 Zeroboard / skin by ROBIN