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Abdelhamid MAA, Son RG, Ki MR, Pack SP. Biosilica-coated carbonic anhydrase displayed on Escherichia coli: A novel design approach for efficient and stable biocatalyst for CO 2 sequestration. Int J Biol Macromol 2024; 277:134058. [PMID: 39038576 DOI: 10.1016/j.ijbiomac.2024.134058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 07/17/2024] [Accepted: 07/19/2024] [Indexed: 07/24/2024]
Abstract
A robust and stable carbonic anhydrase (CA) system is indispensable for effectively sequestering carbon dioxide to mitigate climate change. While microbial surface display technology has been employed to construct an economically promising cell-displayed CO2-capturing biocatalyst, the displayed CA enzymes were prone to inactivation due to their low stability in harsh conditions. Herein, drawing inspiration from biomineralized diatom frustules, we artificially introduced biosilica shell materials to the CA macromolecules displayed on Escherichia coli surfaces. Specifically, we displayed a fusion of CA and the diatom-derived silica-forming Sil3K peptide (CA-Sil3K) on the E. coli surface using the membrane anchor protein Lpp-OmpA linker. The displayed CA-Sil3K (dCA-Sil3K) fusion protein underwent a biosilicification reaction under mild conditions, resulting in nanoscale self-encapsulation of the displayed enzyme in biosilica. The biosilicified dCA-Sil3K (BS-dCA-Sil3K) exhibited improved thermal, pH, and protease stability and retained 63 % of its initial activity after ten reuses. Additionally, the BS-dCA-Sil3K biocatalyst significantly accelerated the CaCO3 precipitation rate, reducing the time required for the onset of CaCO3 formation by 92 % compared to an uncatalyzed reaction. Sedimentation of BS-dCA-Sil3K on a membrane filter demonstrated a reliable CO2 hydration application with superior long-term stability under desiccation conditions. This study may open new avenues for the nanoscale-encapsulation of enzymes with biosilica, offering effective strategies to provide efficient, stable, and economic cell-displayed biocatalysts for practical applications.
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Affiliation(s)
- Mohamed A A Abdelhamid
- Department of Biotechnology and Bioinformatics, Korea University, Sejong-Ro 2511, Sejong 30019, Republic of Korea; Department of Botany and Microbiology, Faculty of Science, Minia University, Minia 61519, Egypt
| | - Ryeo Gang Son
- Department of Biotechnology and Bioinformatics, Korea University, Sejong-Ro 2511, Sejong 30019, Republic of Korea
| | - Mi-Ran Ki
- Department of Biotechnology and Bioinformatics, Korea University, Sejong-Ro 2511, Sejong 30019, Republic of Korea; Institute of Industrial Technology, Korea University, Sejong-Ro 2511, Sejong 30019, Republic of Korea
| | - Seung Pil Pack
- Department of Biotechnology and Bioinformatics, Korea University, Sejong-Ro 2511, Sejong 30019, Republic of Korea.
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Ayieko VO, Cohen L, Diehn S, Goobes G, Elbaum R. Siliplant1 B-domain precipitates silica spheres, aggregates, or gel, depending on Si-precursor to peptide ratios. Colloids Surf B Biointerfaces 2023; 232:113582. [PMID: 37862949 DOI: 10.1016/j.colsurfb.2023.113582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/22/2023]
Abstract
Silica is extensively deposited by plants, however, only little is known about the molecular control over this process. Siliplant1 is the only known plant protein to precipitate biosilica. The protein contains seven repeats made of three domains. One of the domains exhibits a conserved sequence, which catalyzes silica precipitation in vitro. Here, silica was synthesized by the activity of a peptide carrying this conserved sequence. Infrared spectroscopy and thermal gravimetric analyses showed that the peptide was bound to the mineral. Scanning electron microscopy showed that silica-peptide particles of 22 ± 4 nm aggregated to spherical structures of 200-300 nm when the ratio of silicic acid to the peptide was below 183:1 molecules. When the ratio was about 183:1, similar particles aggregated into irregular structures, and silica gel formed at higher ratios. Solid-state NMR spectra indicated that the irregular aggregates were richer in Si-O-Si bonds as well as disordered peptide. Our results suggest that the peptide catalyzed the condensation of silicic acid and the formation of ∼20 nm particles, which aggregated into spheres. Excess of the peptide stabilized surface Si-OH groups that prevented spontaneous Si-O-Si bonding between aggregates. Under Si concentrations relevant to plant sap, the peptide and possibly Siliplant1, could catalyze nucleation of silica particles that aggregate into spherical aggregates.
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Affiliation(s)
- Vincent Otieno Ayieko
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Lilian Cohen
- Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Sabrina Diehn
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel.
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Zexer N, Kumar S, Elbaum R. Silica deposition in plants: scaffolding the mineralization. ANNALS OF BOTANY 2023; 131:897-908. [PMID: 37094329 PMCID: PMC10332400 DOI: 10.1093/aob/mcad056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/20/2023] [Indexed: 05/03/2023]
Abstract
BACKGROUND Silicon and aluminium oxides make the bulk of agricultural soils. Plants absorb dissolved silicon as silicic acid into their bodies through their roots. The silicic acid moves with transpiration to target tissues in the plant body, where it polymerizes into biogenic silica. Mostly, the mineral forms on a matrix of cell wall polymers to create a composite material. Historically, silica deposition (silicification) was supposed to occur once water evaporated from the plant surface, leaving behind an increased concentration of silicic acid within plant tissues. However, recent publications indicate that certain cell wall polymers and proteins initiate and control the extent of plant silicification. SCOPE Here we review recent publications on the polymers that scaffold the formation of biogenic plant silica, and propose a paradigm shift from spontaneous polymerization of silicic acid to dedicated active metabolic processes that control both the location and the extent of the mineralization. CONCLUSION Protein activity concentrates silicic acid beyond its saturation level. Polymeric structures at the cell wall stabilize the supersaturated silicic acid and allow its flow with the transpiration stream, or bind it and allow its initial condensation. Silica nucleation and further polymerization are enabled on a polymeric scaffold, which is embedded within the mineral. Deposition is terminated once free silicic acid is consumed or the chemical moieties for its binding are saturated.
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Affiliation(s)
- Nerya Zexer
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Santosh Kumar
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, K. K. Birla Goa Campus, Zuarinagar 403726, Goa, India
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, Odisha, India
| | - Rivka Elbaum
- R. H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 7610001, Israel
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Sheng H, Li Y, Feng J, Liu Y. Regulation of thermodynamics and kinetics of silica nucleation during the silicification process in higher plants. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 198:107674. [PMID: 37018864 DOI: 10.1016/j.plaphy.2023.107674] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/09/2023] [Accepted: 03/27/2023] [Indexed: 05/07/2023]
Abstract
The formation mechanism of SiO2 aggregates is controversial because two contrasting hypotheses are often proposed to explain plant silicification. In this review, we summarize the physicochemical fundamentals of amorphous silica nucleation and discuss how plants regulate the process of silicification by influencing the thermodynamics and kinetics of silica nucleation. At silicification positions, plants overcome the thermodynamic barrier by establishing the supersaturation of the H4SiO4 solution and reducing the interfacial free energy. Among the thermodynamic-drivers, the establishment of supersaturation of H4SiO4 solution mainly depends on the expression of Si transporters for H4SiO4 supply, evapotranspiration for concentrating Si, and the other solutes in H4SiO4 solution for influencing the dissolution equilibrium of SiO2; while the interfacial free energy was reduced seemingly by the overexpression Na+/H+ antiporter SOS1 in high NaCl-stressed rice. Moreover, some kinetic-drivers, such as silicification-related proteins (Slp1 and PRP1) and new cell wall components, are actively expressed or synthesized by plants to interact with silicic acid, thereby reducing the kinetic barrier. According to classical nucleation theory, when the thermodynamic barrier is overcome, the super-saturated silicic acid solution (such as H4SiO4 in xylem sap) does not necessarily have to precipitate, just has the potential ability to precipitation. Thus, based on the mediators of SiO2 deposition at the thermodynamic-driven stage, it is difficult to evaluate whether the process of plant silicification is active or passive. We conclude that the characteristics of kinetic-drivers determine the mechanism of plant silicification.
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Affiliation(s)
- Huachun Sheng
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Tibetan Plateau Ethnic Medicinal Resources Protection and Utilization Key Laboratory of National Ethnic Affairs Commission of the People's Republic of China, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Sichuan Provincial Qiang-Yi Medicinal Resources Protection and Utilization Technology and Engineering Laboratory, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China.
| | - Ying Li
- Tibetan Plateau Ethnic Medicinal Resources Protection and Utilization Key Laboratory of National Ethnic Affairs Commission of the People's Republic of China, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Sichuan Provincial Qiang-Yi Medicinal Resources Protection and Utilization Technology and Engineering Laboratory, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; College of Pharmacy, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China
| | - Jingqiu Feng
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Tibetan Plateau Ethnic Medicinal Resources Protection and Utilization Key Laboratory of National Ethnic Affairs Commission of the People's Republic of China, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Sichuan Provincial Qiang-Yi Medicinal Resources Protection and Utilization Technology and Engineering Laboratory, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China.
| | - Yuan Liu
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Tibetan Plateau Ethnic Medicinal Resources Protection and Utilization Key Laboratory of National Ethnic Affairs Commission of the People's Republic of China, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China; Sichuan Provincial Qiang-Yi Medicinal Resources Protection and Utilization Technology and Engineering Laboratory, Southwest Minzu University, Chengdu, Sichuan, 610225, PR China.
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Kumar S, Adiram-Filiba N, Blum S, Sanchez-Lopez JA, Tzfadia O, Omid A, Volpin H, Heifetz Y, Goobes G, Elbaum R. Siliplant1 protein precipitates silica in sorghum silica cells. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6830-6843. [PMID: 32485738 DOI: 10.1093/jxb/eraa258] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/26/2020] [Indexed: 05/26/2023]
Abstract
Silicon is absorbed by plant roots as silicic acid. The acid moves with the transpiration stream to the shoot, and mineralizes as silica. In grasses, leaf epidermal cells called silica cells deposit silica in most of their volume using an unknown biological factor. Using bioinformatics tools, we identified a previously uncharacterized protein in Sorghum bicolor, which we named Siliplant1 (Slp1). Slp1 is a basic protein with seven repeat units rich in proline, lysine, and glutamic acid. We found Slp1 RNA in sorghum immature leaf and immature inflorescence. In leaves, transcription was highest just before the active silicification zone (ASZ). There, Slp1 was localized specifically to developing silica cells, packed inside vesicles and scattered throughout the cytoplasm or near the cell boundary. These vesicles fused with the membrane, releasing their content in the apoplastic space. A short peptide that is repeated five times in Slp1 precipitated silica in vitro at a biologically relevant silicic acid concentration. Transient overexpression of Slp1 in sorghum resulted in ectopic silica deposition in all leaf epidermal cell types. Our results show that Slp1 precipitates silica in sorghum silica cells.
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Affiliation(s)
- Santosh Kumar
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Shula Blum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Javier Arturo Sanchez-Lopez
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Tzfadia
- Bioinformatics and Systems Biology, VIB/Ghent University, Gent, Belgium
| | - Ayelet Omid
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Hanne Volpin
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Yael Heifetz
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Rivka Elbaum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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Protein-driven biomineralization: Comparing silica formation in grass silica cells to other biomineralization processes. J Struct Biol 2020; 213:107665. [PMID: 33227416 DOI: 10.1016/j.jsb.2020.107665] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/13/2020] [Accepted: 11/16/2020] [Indexed: 11/20/2022]
Abstract
Biomineralization is a common strategy adopted by organisms to support their body structure. Plants practice significant silicon and calcium based biomineralization in which silicon is deposited as silica in cell walls and intracellularly in various cell-types, while calcium is deposited mostly as calcium oxalate in vacuoles of specialized cells. In this review, we compare cellular processes leading to protein-dependent mineralization in plants, diatoms and sponges (phylum Porifera). The mechanisms of biomineralization in these organisms are inherently different. The composite silica structure in diatoms forms inside the cytoplasm in a membrane bound vesicle, which after maturation is exocytosed to the cell surface. In sponges, separate vesicles with the mineral precursor (silicic acid), an inorganic template, and organic molecules, fuse together and are extruded to the extracellular space. In plants, calcium oxalate mineral precipitates in vacuolar crystal chambers containing a protein matrix which is never exocytosed. Silica deposition in grass silica cells takes place outside the cell membrane when the cells secrete the mineralizing protein into the apoplasm rich with silicic acid (the mineral precursor molecules). Our review infers that the organism complexity and precursor reactivity (calcium and oxalate versus silicic acid) are main driving forces for the evolution of varied mineralization mechanisms.
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