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Yang Zhao,Zhi Liu,Fengying Duan,Xia An,Xiangguo Liu,Dongyun Hao,Riliang Gu,Zhangkui Wang,Fanjun Chen,Lixing Yuan 한국식물생명공학회 2018 Plant biotechnology reports Vol.12 No.1
High-affinity ammonium uptake in maize roots is mainly mediated by AMT1-type ammonium transporters ZmAMT1;1a and ZmAMT1;3, but whether the increased expression of ZmAMTs genes is able to enhance ammonium uptake capacity and subsequently improves overall nitrogen use efficiency remains to be elucidated. In this work, ZmAMT1;1a-overexpression transgenic maize plants were generated with the elevated levels of transcripts and proteins, and phenotypically analyzed together with wild-type plants grown in nutrient solution under two regimes of ammonium supply. Under low ammonium nutrition (0.04 mM), in relative to wild-type plants, the maize transgenic lines showed an approximately 17% increases in the high-affinity ammonium uptake capacity of roots as revealed by 15N-labeled ammonium influx assay and further contributed to about 7% increases in the total nitrogen uptake at the whole plant level. By contrast, when ammonium was supplied in high amounts (1 mM), wild-type plants expressed higher levels of ZmAMT1;1a, but exhibited a lower ammonium uptake capacity in roots. Furthermore, the transgenic maize line accumulated more amounts of ZmAMT1;1a protein, but did not translate into an enhanced ammonium acquisition, suggesting a possible post-translational down-regulation of ZmAMT1;1a by high ammonium. This study proved the possibility to enhance ammonium acquisition by elevating ZmAMTs expression in maize roots and provided an effective transgenic approach on developing high nitrogen use efficient maize cultivars.
( Xiaofeng Zhou ),( Jianghui Li ),( Weilong Wang ),( Fan Yang ),( Bingqian Fan ),( Chenlu Zhang ),( Xiaojun Ren ),( Feng Liang ),( Rong Cheng ),( Fengying Jiang ),( Huaibin Zhou ),( Juanjuan Yang ),( 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7
Various genetically engineered microorganisms have been developed for the removal of heavy metal contaminants. Metal biosorption by whole-cell biosorbents can be enhanced by overproduction of metal-binding proteins/peptides in the cytoplasm or on the cell surface. However, few studies have compared the biosorption capacity of whole cells expressing intracellular or surface-displayed metal-adsorbing proteins. In this study, several constructs were prepared for expressing intracellular and surface-displayed Ochrobactrum tritici 5bvl1 ChrB in Escherichia coli BL21(DE3) cells. E. coli cells expressing surface-displayed ChrB removed more Cr(VI) from aqueous solutions than cells with cytoplasmic ChrB under the same conditions. However, intracellular ChrB was less susceptible to variation in extracellular conditions (pH and ionic strength), and more effectively removed Cr(VI) from industrial wastewater than the surface-displayed ChrB at low pH (<3). An adsorptiondesorption experiment demonstrated that compared with intracellular accumulation, cell-surface adsorption is reversible, which allows easy desorption of the adsorbed metal ions and regeneration of the bioadsorbent. In addition, an intrinsic ChrB protein fluorescence assay suggested that pH and salinity may influence the Cr(VI) adsorption capacity of ChrB-expressing E. coli cells by modulating the ChrB protein conformation. Although the characteristics of ChrB may not be universal for all metal-binding proteins, our study provides new insights into different engineering strategies for whole-cell biosorbents for removing heavy metals from industrial effluents.
( Lili Tian ),( Xinliang Wu ),( Hangqian Yu ),( Fengying Yang ),( Jian Sun ),( Tiezhong Zhou ),( Hong Jiang ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10
The rise of methicillin-resistant Staphylococcus aureus (MRSA) has resulted in significant morbidity and mortality, and clinical treatment of MRSA infections has become extremely difficult. Sortase A (SrtA), a virulence determinant that anchors numerous virulence-related proteins to the cell wall, is a prime druggable target against S. aureus infection due to its crucial role in the pathogenicity of S. aureus. Here, we demonstrate that isovitexin, an active ingredient derived from a variety of traditional Chinese medicines, can reversibly inhibit SrtA activity in vitro with a low dose (IC<sub>50</sub>=24.72 μg/ml). Fluorescence quenching and molecular simulations proved the interaction between isovitexin and SrtA. Subsequent point mutation experiments further confirmed that the critical amino acid positions for SrtA binding to isovitexin were Ala-92, Ile-182, and Trp-197. In addition, isovitexin treatment dramatically reduced S. aureus invasion of A549 cells. This study shows that treatment with isovitexin could alleviate pathological injury and prolong the life span of mice in an S. aureus pneumonia model. According to our research, isovitexin represents a promising lead molecule for the creation of anti-S. aureus medicines or adjuncts.