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Huang LK, Huang YC, Chen PC, Lee CH, Lin SM, Hsu YHH, Pan RL. Exploration of the Catalytic Cycle Dynamics of Vigna Radiata H +-Translocating Pyrophosphatases Through Hydrogen-Deuterium Exchange Mass Spectrometry. J Membr Biol 2023; 256:443-458. [PMID: 37955797 DOI: 10.1007/s00232-023-00295-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 10/11/2023] [Indexed: 11/14/2023]
Abstract
Vigna radiata H+-translocating pyrophosphatases (VrH+-PPases, EC 3.6.1.1) are present in various endomembranes of plants, bacteria, archaea, and certain protozoa. They transport H+ into the lumen by hydrolyzing pyrophosphate, which is a by-product of many essential anabolic reactions. Although the crystal structure of H+-PPases has been elucidated, the H+ translocation mechanism of H+-PPases in the solution state remains unclear. In this study, we used hydrogen-deuterium exchange (HDX) coupled with mass spectrometry (MS) to investigate the dynamics of H+-PPases between the previously proposed R state (resting state, Apo form), I state (intermediate state, bound to a substrate analog), and T state (transient state, bound to inorganic phosphate). When hydrogen was replaced by proteins in deuterium oxide solution, the backbone hydrogen atoms, which were exchanged with deuterium, were identified through MS. Accordingly, we used deuterium uptake to examine the structural dynamics and conformational changes of H+-PPases in solution. In the highly conserved substrate binding and proton exit regions, HDX-MS revealed the existence of a compact conformation with deuterium exchange when H+-PPases were bound with a substrate analog and product. Thus, a novel working model was developed to elucidate the in situ catalytic mechanism of pyrophosphate hydrolysis and proton transport. In this model, a proton is released in the I state, and the TM5 inner wall serves as a proton piston.
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Affiliation(s)
- Li-Kun Huang
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No.101, Sec. 2, Kuangfu Rd., Hsinchu City, 30013, Taiwan, Republic of China
| | - Yi-Cyuan Huang
- Department of Chemistry, Tunghai University, No.1727, Sec. 4, Taiwan Boulevard, Taichung, 40704, Taiwan, Republic of China
| | - Pin-Chuan Chen
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No.101, Sec. 2, Kuangfu Rd., Hsinchu City, 30013, Taiwan, Republic of China
| | - Ching-Hung Lee
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No.101, Sec. 2, Kuangfu Rd., Hsinchu City, 30013, Taiwan, Republic of China
| | - Shih-Ming Lin
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 70101, Taiwan, Republic of China
| | - Yuan-Hao Howard Hsu
- Department of Chemistry, Tunghai University, No.1727, Sec. 4, Taiwan Boulevard, Taichung, 40704, Taiwan, Republic of China.
| | - Rong-Long Pan
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No.101, Sec. 2, Kuangfu Rd., Hsinchu City, 30013, Taiwan, Republic of China.
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Acidophilic bacteria and archaea: acid stable biocatalysts and their potential applications. Extremophiles 2011; 16:1-19. [PMID: 22080280 DOI: 10.1007/s00792-011-0402-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 10/05/2011] [Indexed: 01/05/2023]
Abstract
Acidophiles are ecologically and economically important group of microorganisms, which thrive in acidic natural (solfataric fields, sulfuric pools) as well as artificial man-made (areas associated with human activities such as mining of coal and metal ores) environments. They possess networked cellular adaptations to regulate pH inside the cell. Several extracellular enzymes from acidophiles are known to be functional at much lower pH than the cytoplasmic pH. Enzymes like amylases, proteases, ligases, cellulases, xylanases, α-glucosidases, endoglucanases, and esterases stable at low pH are known from various acidophilic microbes. The possibility of improving them by genetic engineering and directed evolution will further boost their industrial applications. Besides biocatalysts, other biomolecules such as plasmids, rusticynin, and maltose-binding protein have also been reported from acidophiles. Some strategies for circumventing the problems encountered in expressing genes encoding proteins from extreme acidophiles have been suggested. The investigations on the analysis of crystal structures of some acidophilic proteins have thrown light on their acid stability. Attempts are being made to use thermoacidophilic microbes for biofuel production from lignocellulosic biomass. The enzymes from acidophiles are mainly used in polymer degradation.
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