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RISS 인기검색어
- 검색키워드
- 저자 : Bhumi Nath Tripathi (검색결과 3 건)
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Lee, Eun Mi,Lee, Seung Sik,Tripathi, Bhumi Nath,Jung, Hyun Suk,Cao, Guang Ping,Lee, Yuno,Singh, Sudhir,Hong, Sung Hyun,Lee, Keun Woo,Lee, Sang Yeol,Cho, Jae-Young,Chung, Byung Yeoup Academic Press [etc.] 2015 Annals of botany Vol.116 No.4
<P><B>Background and Aims</B> The 2-Cys peroxiredoxin (Prx) A protein of <I>Arabidopsis thaliana</I> performs the dual functions of a peroxidase and a molecular chaperone depending on its conformation and the metabolic conditions. However, the precise mechanism responsible for the functional switching of 2-Cys Prx A is poorly known. This study examines various serine-to-cysteine substitutions on α-helix regions of 2-Cys Prx A in Arabidopsis mutants and the effects they have on the dual function of the protein.</P><P><B>Methods</B> Various mutants of 2-Cys Prx A were generated by replacing serine (Ser) with cysteine (Cys) at different locations by site-directed mutagenesis. The mutants were then over-expressed in <I>Escherichia coli</I>. The purified protein was further analysed by size exclusion chromatography, polyacrylamide gel electrophoresis, circular dichroism spectroscopy and transmission electron microscopy (TEM) and image analysis. Peroxidase activity, molecular chaperone activity and hydrophobicity of the proteins were also determined. Molecular modelling analysis was performed in order to demonstrate the relationship between mutation positions and switching of 2-Cys Prx A activity.</P><P><B>Key Results</B> Replacement of Ser<SUP>150</SUP> with Cys<SUP>150</SUP> led to a marked increase in holdase chaperone and peroxidase activities of 2-Cys Prx A, which was associated with a change in the structure of an important domain of the protein. Molecular modelling demonstrated the relationship between mutation positions and the switching of 2-Cys Prx A activity. Examination of the α<SUB>2</SUB> helix, dimer–dimer interface and C-term loop indicated that the peroxidase function is associated with a fully folded α<SUB>2</SUB> helix and easy formation of a stable reduced decamer, while a more flexible C-term loop makes the chaperone function less likely.</P><P><B>Conclusions</B> Substitution of Cys for Ser at amino acid location 150 of the α-helix of 2-Cys Prx A regulates/enhances the dual enzymatic functions of the 2-Cys Prx A protein. If confirmed <I>in planta</I>, this leads to the potential for it to be used to maximize the functional utility of 2-Cys Prx A protein for improved metabolic functions and stress resistance in plants.</P>
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Lee, Jae Taek,Lee, Seung Sik,Mondal, Suvendu,Tripathi, Bhumi Nath,Kim, Siu,Lee, Keun Woo,Hong, Sung Hyun,Bai, Hyoung-Woo,Cho, Jae-Young,Chung, Byung Yeoup Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.8
Alkyl hydroperoxide reductase subunit C from Pseudomonas aeruginosa PAO1 (PaAhpC) is a member of the 2-Cys peroxiredoxin family. Here, we examined the peroxidase and molecular chaperone functions of PaAhpC using a site-directed mutagenesis approach by substitution of Ser and Thr residues with Cys at positions 78 and 105 located between two catalytic cysteines. Substitution of Ser with Cys at position 78 enhanced the chaperone activity of the mutant (S78C-PaAhpC) by approximately 9-fold compared with that of the wild-type protein (WT-PaAhpC). This increased activity may have been associated with the proportionate increase in the high-molecular-weight (HMW) fraction and enhanced hydrophobicity of S78C-PaAhpC. Homology modeling revealed that mutation of $Ser^{78}$ to $Cys^{78}$ resulted in a more compact decameric structure than that observed in WT-PaAhpC and decreased the atomic distance between the two neighboring sulfur atoms of $Cys^{78}$ in the dimer-dimer interface of S78C-PaAhpC, which could be responsible for the enhanced hydrophobic interaction at the dimer-dimer interface. Furthermore, complementation assays showed that S78C-PaAhpC exhibited greatly improved the heat tolerance, resulting in enhanced1 survival under thermal stress. Thus, addition of Cys at position 78 in PaAhpC modulated the functional shifting of this protein from a peroxidase to a chaperone.
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Byung Yeoup Chung,Jae Taek Lee,Seung Sik Lee,Suvendu Mondal,Bhumi Nath Tripathi,Siu Kim,Keun Woo Lee,Sung Hyun Hong,Hyoung-Woo Bai,Jae-Young Cho 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.8
Alkyl hydroperoxide reductase subunit C from Pseudomonas aeruginosa PAO1 (PaAhpC) is a member of the 2-Cys peroxiredoxin family. Here, we examined the peroxidase and molecular chaperone functions of PaAhpC using a site-directed mutagenesis approach by substitution of Ser and Thr residues with Cys at positions 78 and 105 located between two catalytic cysteines. Substitution of Ser with Cys at position 78 enhanced the chaperone activity of the mutant (S78C-PaAhpC) by approximately 9-fold compared with that of the wild-type protein (WT-PaAhpC). This increased activity may have been associated with the proportionate increase in the high-molecular-weight (HMW) fraction and enhanced hydrophobicity of S78C-PaAhpC. Homology modeling revealed that mutation of Ser78 to Cys78 resulted in a more compact decameric structure than that observed in WT-PaAhpC and decreased the atomic distance between the two neighboring sulfur atoms of Cys78 in the dimer-dimer interface of S78C-PaAhpC, which could be responsible for the enhanced hydrophobic interaction at the dimer-dimer interface. Furthermore, complementation assays showed that S78C-PaAhpC exhibited greatly improved the heat tolerance, resulting in enhanced survival under thermal stress. Thus, addition of Cys at position 78 in PaAhpC modulated the functional shifting of this protein from a peroxidase to a chaperone.
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