분자유전학실험실 (단국대학교 분자생물학과)



 이성욱 ( 2018-03-01 13:50:14 , Hit : 312
 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).







1247   [바이오토픽] CRISPR 특허전쟁 항소심, 브로드 연구소 승리  이성욱 2018/09/11 116
1246   Lenvima OK'd as First-Line Treatment for Unresectable Hepatocellular Carcinoma  이성욱 2018/08/19 134
1245   [바이오토픽] 유전자를 침묵시키는 신약, 20년의 기다림 끝에 승인  이성욱 2018/08/13 155
1244   Doubts arise again about CRISR'd human embryos  이성욱 2018/08/09 148
1243   CRISPR-Cas12a More Precise Than CRISPR-Cas9  이성욱 2018/08/07 146
1242   Lethal Viruses Hijack DNA-Damage Response, May Be Exploited for Cancer  이성욱 2018/08/07 130
1241   Ruling on gene editing crops a threat to innovation and future food security, scientists say  이성욱 2018/07/28 120
1240   Another "CRISPR Calamity"? U.K. Team Reports CRISPR-Induced Gene Rearrangements  이성욱 2018/07/17 148
1239   Cause of CRISPR Failure Identified and Reversed  이성욱 2018/07/12 187
1238   CRISPR Efficiency Tied to Cancer-Causing Process  이성욱 2018/06/13 192
1237   Gene Therapy Ever More Common for Rare Disorders  이성욱 2018/05/30 204
1236   RNA World May Have Started Spinning with Triplet-Based Synthesis  이성욱 2018/05/21 187
1235   CRISPR’s MAGESTIC Evolution Makes Gene Editing More Precise  이성욱 2018/05/08 282
1234   CRISPR-Cas9 Improved 10,000-Fold by Synthetic Nucleotides  이성욱 2018/04/17 281
1233   Nature Methods retracts CRISPR study  이성욱 2018/04/10 482
1232   릴리 '시람자' 간암 말기 임상시험 성공  이성욱 2018/04/07 328
  Powerful enzyme could make CRISPR gene-editing more versatile  이성욱 2018/03/01 312
1230   Severe Toxicity Reported in High-Dose AAV Gene Therapy in Animals  이성욱 2018/02/01 507
1229   Shields Up for New Cancer Gene-Therapy Virus  이성욱 2018/02/01 398
1228   JPM서 논란 ‘유전자가위 기술’ 올해의 마일스톤은?  이성욱 2018/01/21 751

[1] 2 [3][4][5][6][7][8][9][10]..[64] [다음 10개]
 

Copyright 1999-2019 Zeroboard / skin by ROBIN