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Molecular insights into DNA interference by CRISPR-associated nuclease-helicase Cas3
Gong, Bei,Shin, Minsang,Sun, Jiali,Jung, Che-Hun,Bolt, Edward L.,van der Oost, John,Kim, Jeong-Sun National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.46
<P><B>Significance</B></P><P>Bacteria can repel invader DNA and RNA molecules by using an adaptive immunity mechanism called clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas. CRISPR loci in a host genome are a repository of DNA fragments obtained from previous encounters with an invader, which can be transcribed and activated into short RNA molecules (crRNA) with sequences complementary to invader DNA or RNA. In some CRISPR-Cas systems, crRNA is assembled into a targeting complex called “Cascade” that seeks invader DNA to form an R-loop that triggers recruitment of a nuclease-helicase, Cas3, to destroy invader DNA. In this study, we show atomic resolution structures of a full-length Cas3, revealing how Cas3 coordinates binding, ATP-dependent translocation, and nuclease digestion of invader DNA.</P><P>Mobile genetic elements in bacteria are neutralized by a system based on clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins. Type I CRISPR-Cas systems use a “Cascade” ribonucleoprotein complex to guide RNA specifically to complementary sequence in invader double-stranded DNA (dsDNA), a process called “interference.” After target recognition by Cascade, formation of an R-loop triggers recruitment of a Cas3 nuclease-helicase, completing the interference process by destroying the invader dsDNA. To elucidate the molecular mechanism of CRISPR interference, we analyzed crystal structures of Cas3 from the bacterium <I>Thermobaculum terrenum</I>, with and without a bound ATP analog. The structures reveal a histidine-aspartate (HD)-type nuclease domain fused to superfamily-2 (SF2) helicase domains and a distinct C-terminal domain. Binding of ATP analog at the interface of the SF2 helicase RecA-like domains rearranges a motif V with implications for the enzyme mechanism. The HD-nucleolytic site contains two metal ions that are positioned at the end of a proposed nucleic acid-binding tunnel running through the SF2 helicase structure. This structural alignment suggests a mechanism for 3′ to 5′ nucleolytic processing of the displaced strand of invader DNA that is coordinated with ATP-dependent 3′ to 5′ translocation of Cas3 along DNA. In agreement with biochemical studies, the presented Cas3 structures reveal important mechanistic details on the neutralization of genetic invaders by type I CRISPR-Cas systems.</P>
Nattokinase Crude Extract Inhibits Hepatocellular Carcinoma Growth in Mice
( Yongmin Yan ),( Yanjing Wang ),( Jiali Qian ),( Sihui Wu ),( Yi Ji ),( Yanxiao Liu ),( Jian Zeng ),( Aihua Gong ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.8
Nattokinase (NK, E.C. 3.4.21.62) is a serine protease produced by Bacillus subtilis natto that shows promise for the treatment of thrombotic disease. In this study, we assessed the effects of NK on the development of hepatocellular carcinoma (HCC), a principal malignancy of the liver that causes morbidity and mortality worldwide. Crude extracts of NK (NCE) were isolated from fermentation medium by centrifugation and separated into three fractions (< 10 K, 100~30 K and >30K). Orthotopic HCC mouse models were established and NCE was administered by oral gavage. H&E staining was performed to examine the pathology of HCC livers. Immunohistochemistry and immunofluorescence were used to evaluate FOXM1, CD31, CD44 and vimentin expression in the liver. Compared to PBS groups, NCE increased the survival rates of HCC-bearing mice to 31% and decreased ascites. Low-intensity ultrasound imaging showed that the hypoechoic mass area was lower in NCE-treated mice and that tumor growth significantly decreased. IHC staining showed that the expression of FOXM1 was inhibited by NCE treatment. Immunofluorescence results revealed lower levels of CD31, CD44 and vimentin in the NCE groups. Taken together, these data demonstrate that NCE from Bacillus subtilis natto improves survival and inhibits tumor growth in HCC mice.
Shi Yihan,Zhang Ming,Zhao Junshan,Zhang Liu,Cui Xumei,Zhu Xinhua,Jin Dandan,Gong Jiali,Yang Dingyu,Li Jitao 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.5
This work used a simple electrochemical reduction method to secondary construct the reduced nickel base (rNi Base) on nickel foam with a nano-core structure. The secondarily constructed base has a large specific surface area, which can increase the mass utilization of the active material. The rNi Base was used as a base for the reduction of nickel on Na+, K+, and NH+4, respectively. MnO2 was electrodeposited under three different cation pre-intercalation treatments, and the mechanism of the effect of different monovalent cations to guide the growth of MnO2 materials was investigated. Finally, rNi/MnO2&Na+ electrode with a special nano cauliflower structure was obtained. The special nanostructure of the electrode enhances its electrochemical performance, possessing 598 F g− 1 ultra-high specific capacitance at a current density of 1 A g− 1 and a high specific capacitance of 307.5 F g− 1 at a high current density of 20 A g− 1, and high specific capacitance maintenance rate of 92.7% after 500 cycles of charging and discharging at a current density of 2 A g− 1. In addition, the symmetrical supercapacitor assembled with this electrode has a very high specific capacitance (401.1 F g− 1 at a current density of 1 A g− 1) and energy density (80.22Wh kg− 1 at a power density of 599.99 W kg− 1).