[Latest Research Progress ] Important Progress in Prokaryotic Argonaute Protein

　　 　　

Recently, Professor Zhang Zhiying's team in the College has made important progress in the research of DNA interference property of prokaryotic Argonaute protein in in vivo. The research paper was published online in mBio with the title "Prokaryotic Argonaute Protein from Natronobacteriumgregoryi Requires RNAs To Activate for DNA Interference In Vivo". Xing Jiani, a Ph.D. graduate of the College, and Ma Lixia, a Ph.D. student, are co-first authors, and Professor Zhang Zhiying and Professor Joe S. Mymryk of Weston University in Canada are co-correspondents.  

Because prokaryotic Argonaute protein has the ability to cut DNA or RNA in vitro, it is expected to be developed into a new generation of "artificial nuclease", which can be used for genome editing. At present, the research on prokaryotic Argonaute protein is very popular, but the research results that prove that Argonaute has the function of "nuclease" in vivo are almost blank. Professor Zhang Zhiying's team has been engaged in gene editing research for many years, and devoted himself to studying the function and working mechanism of prokaryotic Argonaute protein in vivo. It was found that NgAgo can activate its nuclease activity by specific RNA in Escherichia coli cells, thus targeting plasmid DNA. Cutting leads to its linearization; DNA interference is formed between homologous sequences of genome and plasmid DNA to eliminate exogenous DNA production; Furthermore, T7 phage was used to prove that NgAgo and its mutant protein can significantly protect Escherichia coli cells from being lysed by T7 phage, and destroy phage genomic DNA to provide immune defense system for bacteria. All the above results indicate that prokaryotic Argonaute protein acts as an inherent defense system of prokaryotes to exercise its physiological functions.

This study expounded the action mechanism of prokaryotic Argonaute protein in bacterial cells, solved the difficult problems in the research field of prokaryotic Argonaute protein for decades, and realized DNA cleavage by NgAgo protein in bacterial cells for the first time. In this study, NgAgo protein was innovatively put forward as a "monitoring" hypothesis of prokaryotic defense mechanism: prokaryotic Argonaute protein was activated by transcripts of exogenous nucleotides (such as viruses or plasmids) promoters and targeted to clear exogenous nucleotides to defend against the invasion of viruses and exogenous DNA. This study lays an important theoretical foundation for developing prokaryotic Argonaute protein as a new generation of gene editing tool instead of CRISPR/Cas9 in the future.

The research results are supported by relevant national projects.

Original link: https://journals.asm.org/doi/10.1128/mbio.03656-21