CATALYSIS LETTERS
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2018
·Vol. 148
·期 6
·1714-1722
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IF 2.911
Luo Wei,Deng Xin-Xing,Huo Jiao,Ruan Tao,Gong Zhi-Wei,Yan Jia-Bao,Yang Zhong-Hua,Quan Can,Cui Zhi-Fang
Abstract Microalgae are excellent biocatalyst candidates for photo-biocatalytic-asymmetric reduction of prochiral ketones to produce enantiomer alcohols. In the biocatalysis asymmetric reduction of carbonyl group process, the cofactor, NADPH, plays a key role. So the current study focused on the effect of NADPH availability on the reduction. Photosynthesis is a main pathway for NADPH regeneration in microalgae, and the ferredoxin-NADP + oxidoreductase (FNR) is the key enzyme in this process. In this work, we constructed an engineered cyanobacterium Synechocystis sp. PCC6803:: Ω- P petE-petH to overexpress FNR gene petH to strengthen NADPH regeneration. The results show that the intracellular NADPH content was increased 80.8% compared to the wild type. Applying the Synechocystis sp. PCC6803:: Ω- P petE-petH to catalyze the model asymmetric reduction reaction (reduction of acetophenone to S -phenylethanol), the yield was improved 61.2% compared to the wild-type. This work makes the microalgal biocatalysis asymmetric reduction process become more preponderant via providing a new route to enhance the regeneration of cofactor NADPH. Graphical Abstract Putative metabolic process of nicotinamide adenine dinucleotide phosphate (NADPH) regeneration and the photo-biocatalytic-asymmetric reduction reaction of prochiral ketones in microalgal cells.
研究领域:
生物化学
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合成生物学
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DOI
高影响因子
Biotechnology for Biofuels
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2018
·Vol. 11
·期 1
·1-15
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IF 5.497
Xu Chunxiao,Sun Tao,Li Shubin,Chen Lei,Zhang Weiwen
Background Cadmium has been a significant threat to environment and human health due to its high toxicity and wide application in fossil-fuel burning and battery industry. Cyanobacteria are one of the most dominant prokaryotes, and the previous studies suggested that they could be valuable in removing Cd2+ from waste water. However, currently, the tolerance to cadmium is very low in cyanobacteria. To further engineer cyanobacteria for the environmental application, it is thus necessary to determine the mechanism that they respond to high concentration of cadmium.Results In this study, a robust strain of Synechocystis PCC 6803 (named ALE-9.0) tolerant to CdSO4 with a concentration up to 9.0 µM was successfully isolated via adaptive laboratory evolution over 802-day continuous passages under cadmium stress. Whole-genome re-sequencing was then performed and nine mutations were identified for the evolved strain compared to the wild-type strain. Among these mutations, a large fragment deletion in slr0454 encoding a cation or drug efflux system protein was found to contribute directly to the resistance to Cd2+ stress. In addition, five other mutations were also demonstrated related to the improved Cd2+ tolerance in ALE-9.0. Moreover, the evolved ALE-9.0 strain was found to obtain cross tolerance to some other heavy metals like zinc and cobalt as well as higher resistance to high light.Conclusion sThe work here identified six genes and their mutations related to Cd2+ tolerance in Synechocystis PCC 6803, and demonstrated the feasibility of adaptive laboratory evolution in tolerance modifications. This work also provided valuable information regarding the cadmium tolerance mechanism in Synechocystis PCC 6803, and useful insights for cyanobacterial robustness and tolerance engineering.
研究领域:
环境科学
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微生物学
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基因组学
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生物技术
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产品关联
DOI
PubMed
高影响因子
Communications Biology
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2026
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IF 5.8
Lu Yiping,Wang Chongyang,Zhang Keke,Zhang Zhichao,Xu Huifang,Wu Danni,Zhao Kun,Ma Honglei,Lu Xuefeng
Coordinating phosphate acquisition with overall nutritional status is critical for cyanobacterial survival in oligotrophic environments, yet the molecular basis for substrate selectivity in phosphate-binding proteins (PBPs) remains incompletely understood. Here we reveal two evolutionarily distinct PBP architectures in Synechocystis sp. PCC 6803 through integrative structural and biochemical analyses. High-resolution crystal structures (1.76–1.9 Å) of PstS1 and SphX bound to inorganic phosphate (Pi) demonstrate that D-type PBPs utilize a conserved aspartate-mediated low-barrier hydrogen bond (LBHB) for high-affinity Pi binding (nanomolar Kd), whereas S-type SphX employs a previously uncharacterized Asp-Arg-Thr catalytic triad with reduced affinity (micromolar Kd). Despite forming comparable hydrogen bonding networks (14 versus 15 bonds), SphX exhibits 26-fold lower Pi affinity due to threonine-mediated proton acceptance replacing the LBHB mechanism. Systematic mutagenesis confirms the functional importance of each triad residue and indicates partial compensation by neighboring residues. Phylogenetic analysis demonstrates that these architectural variants are conserved across cyanobacterial lineages, representing adaptive solutions to diverse nutrient-limited environments. Our findings establish a mechanistic framework for understanding PBP functional diversification and provide molecular insights relevant to optimizing cyanobacterial productivity in biotechnology applications.
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PubMed
高影响因子
ENVIRONMENTAL POLLUTION
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2021
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IF 8.071
Kui Xu,Zhou Li,Philippe Juneau,Fanshu Xiao,Yingli Lian,Wei Zhang,Longfei Shu,Haibo Jiang,Keke Zhang,Cheng Wang,Shanquan Wang,Qingyun Yan,Zhili He
An increasing production and use of titanium dioxide nanoparticles (TiO 2 NPs) pose a huge threat to phytoplankton since they are largely released into aquatic environments, which represent a sink for TiO 2 NPs. However, toxicity and protective mechanisms of cyanobacteria in response to TiO 2 NPs remain elusive. Here we investigated toxic effects of two sizes of TiO 2 NPs (50 and 10 nm) and one bulk TiO 2 (200 nm) on a cyanobacterium, Synechocystis sp. and their possible protective mechanisms. We found that 10 nm TiO 2 NPs caused significant growth and photosynthesis inhibition in Synechocystis sp . cells, largely reflected in decreased growth rate (38%), operational PSII quantum yields (40%), phycocyanin (51%) and allophycocyanin (63%), and increased reactive oxygen species content (245%), superoxide dismutase activity (46%). Also, transcriptomic analysis of Synechocystis sp. exposure to 10 nm TiO 2 NPs showed the up-regulation of D1 and D2 protein genes ( psbA and psbD ), ferredoxin gene ( petF ) and F-type ATPase genes (e.g., atpB ), and the down-regulation of psbM and psb28-2 in PS II. We further proposed a conceptual model to explore possible toxic and protective mechanisms for Synechocystis sp. under TiO 2 nanoparticle exposure. This study provides mechanistic insights into our understanding of Synechocystis sp. responses to TiO 2 NPs. This is essential for more accurate environmental risk assessment approaches of nanoparticles in aquatic ecosystems by governmental environmental agencies worldwide.
研究领域:
环境科学
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微生物学
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产品关联
DOI
PubMed
高影响因子
Frontiers in Microbiology
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2020
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IF 4.236
Wang Xiaoshuai,Chen Lei,Liu Jing,Sun Tao,Zhang Weiwen
myo-inositol (MI) is an essential growth factor, nutritional source, and important precursor for many derivatives like D-chiro-inositol. In this study, attempts were made to achieve the “green biosynthesis” of MI in a model photosynthetic cyanobacterium Synechocystis sp. PCC 6803. First, several genes encoding myo-inositol-1-phosphate synthases and myo-inositol-1-monophosphatase, catalyzing the first or the second step of MI synthesis, were introduced, respectively, into Synechocystis. The results showed that the engineered strain carrying myo-inositol-1-phosphate synthase gene from Saccharomyces cerevisiae was able to produce MI at 0.97 mg L–1. Second, the combined overexpression of genes related to the two catalyzing processes increased the production up to 1.42 mg L–1. Third, to re-direct more cellular carbon flux into MI synthesis, an inducible small RNA regulatory tool, based on MicC-Hfq, was utilized to control the competing pathways of MI biosynthesis, resulting in MI production of ∼7.93 mg L–1. Finally, by optimizing the cultivation condition via supplying bicarbonate to enhance carbon fixation, a final MI production up to 12.72 mg L–1 was achieved, representing a ∼12-fold increase compared with the initial MI-producing strain. This study provides a light-driven green synthetic strategy for MI directly from CO2 in cyanobacterial chassis and represents a renewable alternative that may deserve further optimization in the future.
研究领域:
微生物学
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生物技术
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合成生物学
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DOI
PubMed
高影响因子
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
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2023
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IF 3.1
Yilan Li,Haowei Wang,Lingfang Tang,Huawei Zhu
Photosynthetic microorganisms such as cyanobacteria can convert photons into electrons, providing ideal eco-friendly materials for converting solar energy into electricity. However, the electrons are hardly transported outside the cyanobacterial cells due to the insulation feature of the cell wall/membrane. Various nanomaterials have been reported to enhance extracellular electron transfer of heterotrophic electroactive microorganisms, but its effect on intact photosynthetic microorganisms remains unclear. In this study, we investigated the effect of six different nanomaterials on the photocurrent generation of cyanobacterium Synechocystis sp. PCC 6803. Among the nanomaterials tested, titanium dioxide (TiO 2 ) nanoparticles increased the photocurrent generation of Synechocystis sp. PCC 6803 up to four-fold at the optimum concentration of 2 mg/mL. Transmission electron microscopy and scanning electron microscopy showed that TiO 2 bound to cyanobacterial cells and likely penetrated inside of cell membrane. Photochemical analyses for photosystems showed that TiO 2 blocked the electrons transfer downstream in PS I, implying a possible extracellular electron pathway mediated by TiO 2 . This study provides an alternative approach for enhancing the photocurrent generation of cyanobacteria, showing the potential of photosynthetic-nanomaterial hybrids.
研究领域:
生物技术
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纳米技术
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环境科学
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微生物学
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DOI
PubMed
高影响因子
Biotechnology for Biofuels
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2018
·Vol. 11
·期 1
·1-16
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IF 5.497
Sun Tao,Li Shubin,Song Xinyu,Pei Guangsheng,Diao Jinjin,Cui Jinyu,Shi Mengliang,Chen Lei,Zhang Weiwen
Background Photosynthetic cyanobacteria have attracted a significant attention as promising chassis to produce renewable fuels and chemicals due to their capability to utilizing solar energy and CO 2 . Notably, the enhancing supply of key precursors like malonyl-CoA would benefit the production of many bio-compounds. Nevertheless, the lacking of genetic tools in cyanobacteria, especially the knockdown strategies for essential pathways, has seriously restricted the attempts to re-direct carbon flux from the central carbohydrate metabolism to the synthesis of bioproducts. Results Aiming at developing new genetic tools, two small RNA regulatory tools are reported for the model cyanobacterium Synechocystis sp. PCC6803, based on paired termini RNAs as well as the exogenous Hfq chaperone and MicC scaffold (Hfq-MicC) previously developed in Escherichia coli . Both regulatory tools functioned well in regulating exogenous reporter gene lacZ and endogenous glgC gene in Synechocystis sp. PCC6803, achieving a downregulation of gene expression up to 90% compared with wildtype. In addition, the Hfq-MicC tool was developed to simultaneously regulate multiple genes related to essential fatty acids biosynthesis, which led to decreased fatty acids content by 11%. Furthermore, aiming to re-direct the carbon flux, the Hfq-MicC tool was utilized to interfere the competing pathway of malonyl-CoA, achieving an increased intracellular malonyl-CoA abundance up to 41% (~ 698.3 pg/mL/OD 730 nm ) compared to the wildtype. Finally, the Hfq-MicC system was further modified into an inducible system based on the theophylline-inducible riboswitch. Conclusions In this study, two small RNA regulatory tools for manipulating essential metabolic pathways and re-directing carbon flux are reported for Synechocystis sp. PCC6803. The work introduces efficient and valuable metabolic regulatory strategies for photosynthetic cyanobacteria.
研究领域:
微生物学
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代谢工程
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合成生物学
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DOI
PubMed
高影响因子
ACS Nano
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2024
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IF 15.8
Tao Sun,Huaishu Huo,Yingying Zhang,Yaru Xie,Yize Li,Kungang Pan,Fenfang Zhang,Jing Liu,Yindong Tong,Weiwen Zhang,Lei Chen
The pollution caused by heavy metals (HMs) represents a global concern due to their serious environmental threat. Photosynthetic cyanobacteria have a natural niche and the ability to remediate HMs such as cadmium. However, their practical application is hindered by a low tolerance to HMs and issues related to recycling. In response to these challenges, this study focuses on the development and evaluation of engineered cyanobacteria-based living materials for HMs bioremediation. Genes encoding phytochelatins (PCSs) and metallothioneins (MTs) were introduced into the model cyanobacterium Synechocystis sp. PCC 6803, creating PM/6803. The strain exhibited improved tolerance to multiple HMs and effectively removed a combination of Cd2+, Zn2+, and Cu2+. Using Cd2+ as a representative, PM/6803 achieved a bioremediation rate of approximately 21 μg of Cd2+/OD750 under the given test conditions. To facilitate its controllable application, PM/6803 was encapsulated using sodium alginate-based hydrogels (PM/6803@SA) to create “living materials” with different shapes. This system was feasible, biocompatible, and effective for removing Cd2+ under simulated conditions of zebrafish and mice models. Briefly, in vitro application of PM/6803@SA efficiently rescued zebrafish from polluted water containing Cd2+, while in vivo use of PM/6803@SA significantly decreased the Cd2+ content in mice bodies and restored their active behavior. The study offers feasible strategies for HMs bioremediation using the interesting biomaterials of engineered cyanobacteria both in vitro and in vivo.
研究领域:
环境科学
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微生物学
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生物技术
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材料科学
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产品关联
DOI
PubMed
高影响因子
Algal Research-Biomass Biofuels and Bioproducts
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2019
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IF 3.723
Nitin Keshari,Muriel Gugger,Tao Zhu,Xuefeng Lu
Cyanobacteria are promising cell factories for producing high-value bioproducts . They accumulate low molecular mass organic molecules under salinity stress conditions, which are known as compatible solutes, e.g. sucrose , trehalose , and glucosylglycerol (GG). The physiological properties of compatible solutes sort them as the potential bioproducts for applications in the field of health, pharmacy, and cosmetic sectors. During last few decades, mostly model cyanobacterial strains (unicellular from freshwater and marine habitats) have been targeted for the biochemical and molecular characterization of compatible solutes accumulation, while, the study on other cyanobacteria from extreme/stressful habitats are scanty. The advantage for selecting multicellular cyanobacteria in the present study is their easier harvesting mode over unicellular strains which are one of the primary concerns for the cost-effective production of desired products at pilot scale. Therefore, five cyanobacterial strains with diverse morphotypes belonging to subsection I (Unicellular), II (Baeocytous), III (Filamentous), and V (Ramified) isolated from extreme/stressful habitats (sewage pond and hot spring including freshwater strain as a reference) were screened for salt tolerance , compatible solutes profiling, and sugar feedstock production. High GG, sucrose, and glycogen production were found in Leptolyngbya sp. PCC 8913, Chroogloeocystis siderophila NIES-1031 and Fischerella major NIES-592, respectively. Under salt stress, Leptolyngbya sp. PCC 8913 showed a GG production of 101 ± 12 mg/L/OD 730 , which is significantly higher than that of the model strain Synechocystis sp. PCC 6803. Fischerella major NIES-592 and Oscillatoria laetevirens NIES-31 were identified as novel trehalose-producing cyanobacteria. The key genes involved in production of compatible solutes among these cyanobacteria were also studied. Thus, the results not only displayed the potential cyanobacteria for production of GG, sucrose, trehalose and glycogen but also address the metabolic pathways for the compatible solutes biosynthesis in diversified cyanobacteria, which can be further targeted for the in-depth study to enhance the production using molecular approaches.
研究领域:
微生物学
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生物技术
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生物化学
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分子生物学
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产品关联
DOI
高影响因子
Catalysis Science & Technology
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2019
·Vol. 9
·期 6
·1504-1510
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IF 5.726
Shanshan Yu,Peiyuan Yao,Jinlong Li,Jinhui Feng,Qiaqing Wu,Dunming Zhu
Nitrilase-catalysed desymmetrization of 3-substituted glutaronitriles to optically active 3-substituted 4-cyanobutanoic acid offers an attractive approach to access chiral β-substituted γ-amino acids, an important moiety in pharmaceuticals. In this study, we employed enzyme-substrate docking and alanine scanning to determine the key amino acid residues which have a positive effect on the activity and stereoselectivity of a nitrilase from Synechocystis sp. PCC6803 (SsNIT). Then, site-saturation mutagenesis and combinatorial mutagenesis of the positive amino acid residues (H141, P194, M197, I201 and F202) were performed, and a double mutant (P194A/F202V) and a triple mutant (P194A/I201A/F202V) with high activity and stereoselectivity were identified for desymmetrization of 3-substituted glutaronitriles to afford (S)-3-substituted-4-cyanobutanoic acids with a high space–time productivity of up to 488 g L−1 d−1. Molecular calculation suggests that the enzymatic activity improvement may be due to the enlargement of the substrate binding cavity. It is interesting that the stereoselectivity is enhanced simultaneously.
研究领域:
生物催化
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酶工程
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化学生物合成
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DOI
高影响因子
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