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Glutamine Synthetase Contributes to the Regulation of Growth, Conidiation, Sclerotia Development, and Resistance to Oxidative Stress in the Fungus Aspergillus flavus. Toxins (Basel) 2022; 14:toxins14120822. [PMID: 36548719 PMCID: PMC9785230 DOI: 10.3390/toxins14120822] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/12/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
The basic biological function of glutamine synthetase (Gs) is to catalyze the conversion of ammonium and glutamate to glutamine. This synthetase also performs other biological functions. However, the roles of Gs in fungi, especially in filamentous fungi, are not fully understood. Here, we found that conditional disruption of glutamine synthetase (AflGsA) gene expression in Aspergillus flavus by using a xylose promoter leads to a complete glutamine deficiency. Supplementation of glutamine could restore the nutritional deficiency caused by AflGsA expression deficiency. Additionally, by using the xylose promoter for the downregulation of AflgsA expression, we found that AflGsA regulates spore and sclerotic development by regulating the transcriptional levels of sporulation genes abaA and brlA and the sclerotic generation genes nsdC and nsdD, respectively. In addition, AflGsA was found to maintain the balance of reactive oxygen species (ROS) and to aid in resisting oxidative stress. AflGsA is also involved in the regulation of light signals through the production of glutamine. The results also showed that the recombinant AflGsA had glutamine synthetase activity in vitro and required the assistance of metal ions. The inhibitor molecule L-α-aminoadipic acid suppressed the activity of rAflGsA in vitro and disrupted the morphogenesis of spores, sclerotia, and colonies in A. flavus. These results provide a mechanistic link between nutrition metabolism and glutamine synthetase in A. flavus and suggest a strategy for the prevention of fungal infection.
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Lv Q, Hu M, Tian L, Liu F, Wang Q, Xu M, Rao Z. Enhancing l-glutamine production in Corynebacterium glutamicum by rational metabolic engineering combined with a two-stage pH control strategy. BIORESOURCE TECHNOLOGY 2021; 341:125799. [PMID: 34425465 DOI: 10.1016/j.biortech.2021.125799] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
l-glutamine is a semi-essential amino acid widely used in the food and pharmaceutical industries. The microbial synthesis of l-glutamine is limited by lack of effective strains with high titer and safety. First, ARTP mutagenesis combined with high-throughput screening generated an l-glutamine-producing strain of Corynebacterium glutamicum with titer of 25.7 ± 2.7 g/L. Subsequently, a series of rational metabolic approaches were used to further improve l-glutamine production, which included increasing the carbon flow to l-glutamine (proB and NCgl1221 knockout), enhancing the catalytic efficiency of the key enzyme (glnE knockout and glnA screening and overexpression) and reinforcement of ATP regeneration (ppk overexpression and RBS optimization). Finally, we proposed a two-stage pH control strategy to address the inconsistent effect of pH on cell growth and l-glutamine production. These combined strategies led to a 186.0% increase of l-glutamine titer compared to that of the initial strain, reaching 73.5 ± 3.1 g/L with a yield of 0.368 ± 0.034 g/g glucose.
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Affiliation(s)
- Qinglan Lv
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Mengkai Hu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Lingzhi Tian
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Fei Liu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Qing Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Meijuan Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China
| | - Zhiming Rao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province 214122, PR China.
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Gong C, You X, Zhang S, Xue D. Functional Analysis of a Glutamine Biosynthesis Protein from a Psychrotrophic Bacterium, Cryobacterium soli GCJ02. Indian J Microbiol 2020; 60:153-159. [PMID: 32255847 DOI: 10.1007/s12088-020-00858-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 01/30/2020] [Indexed: 11/25/2022] Open
Abstract
A putative glutamine synthetase (GS) was detected in a psychrophilic bacterium, Cryobacterium soli GCJ02. For gaining greater insight into its functioning, the gene was cloned and expressed in a heterologous host, Escherichia coli. The monomer enzyme with a molecular weight of 53.03 kDa was expressed primarily in cytosolic compartment. The enzyme activity was detected using glutamate and ATP. The optimum conditions of its biosynthesis were observed to be 60 °C and pH value 7.5. Its thermostability was relatively high with a half-life of 50 min at 40 °C. GS activity was enhanced in the presence of metal ions such as Mg2+ and Mn2+, whereas Fe2+, Cu2+ and Ca2+ proved inhibitory. The consensus pattern [EXE]-D-KP-[XGXGXH] in the GS lies between residues 132 and 272. The catalytic active sites consisting of EAE and NGSGMH were verified by site-directed mutagenesis. Based on the analysis of the consensus pattern, the GS/glutamate synthase cycle of C. soli GCJ02 is expected to contribute to the GS synthesic activity.
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Affiliation(s)
- Chunjie Gong
- 1Key Laboratory of Fermentation Engineering (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, 430068 People's Republic of China
| | - Xihuo You
- 2Mudanjiang Normal University, Mudanjiang, 157011 People's Republic of China
| | - Shuyang Zhang
- 1Key Laboratory of Fermentation Engineering (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, 430068 People's Republic of China
| | - Dongsheng Xue
- 1Key Laboratory of Fermentation Engineering (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, 430068 People's Republic of China
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Ma Q, Cao X, Wu L, Mi W, Feng Y. Light intensity affects the uptake and metabolism of glycine by pakchoi (Brassica chinensis L.). Sci Rep 2016; 6:21200. [PMID: 26882864 PMCID: PMC4756379 DOI: 10.1038/srep21200] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 01/19/2016] [Indexed: 12/21/2022] Open
Abstract
The uptake of glycine by pakchoi (Brassica chinensis L.), when supplied as single N-source or in a mixture of glycine and inorganic N, was studied at different light intensities under sterile conditions. At the optimal intensity (414 μmol m(-2) s(-1)) for plant growth, glycine, nitrate, and ammonium contributed 29.4%, 39.5%, and 31.1% shoot N, respectively, and light intensity altered the preferential absorption of N sources. The lower (15)N-nitrate in root but higher in shoot and the higher (15)N-glycine in root but lower in shoot suggested that most (15)N-nitrate uptake by root transported to shoot rapidly, with the shoot being important for nitrate assimilation, and the N contribution of glycine was limited by post-uptake metabolism. The amount of glycine that was taken up by the plant was likely limited by root uptake at low light intensities and by the metabolism of ammonium produced by glycine at high light intensities. These results indicate that pakchoi has the ability to uptake a large quantity of glycine, but that uptake is strongly regulated by light intensity, with metabolism in the root inhibiting its N contribution.
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Affiliation(s)
- Qingxu Ma
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Xiaochuang Cao
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Lianghuan Wu
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Wenhai Mi
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Ying Feng
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
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