1
|
Gui R, Jin H. Organic fluorophores-based molecular probes with dual-fluorescence ratiometric responses to in-vitro/in-vivo pH for biosensing, bioimaging and biotherapeutics applications. Talanta 2024; 275:126171. [PMID: 38703479 DOI: 10.1016/j.talanta.2024.126171] [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: 01/31/2024] [Revised: 04/19/2024] [Accepted: 04/25/2024] [Indexed: 05/06/2024]
Abstract
In recent years, organic fluorophores-based molecular probes with dual-fluorescence ratiometric responses to in-vitro/in-vivo pH (DFR-MPs-pH) have been attracting much interest in fundamental application research fields. More and more scientific publications have reported the exploration of various DFR-MPs-pH systems that have unique dual-fluorescence ratiometry as the signal output, in-built and signal self-calibration functions to improve precise detection of targets. DFR-MPs-pH systems possess high-performance applications in biosensing, bioimaging and biomedicine fields. This review has comprehensively summarized recent advances of DFR-MPs-pH for the first time. First of all, the compositions and types of DFR-MPs-pH are introduced by summarizing different organic fluorophores-based molecule systems. Then, construction strategies are analyzed based on specific components, structures, properties and functions of DFR-MPs-pH. Afterward, biosensing and bioimaging applications are discussed in detail, primarily referring to pH sensing and imaging detection at the levels of living cells and small animals. Finally, biomedicine applications are fully summarized, majorly involving bio-toxicity evaluation, bio-distribution, biomedical diagnosis and therapeutics. Meanwhile, the current status, challenges and perspectives are rationally commented after detailed discussions of representative and state-of-the-art studies. Overall, this present review is comprehensive, in-time and in-depth, and can facilitate the following further exploration of new and versatile DFR-MPs-pH systems toward rational design, facile preparation, superior properties, adjustable functions and highly efficient applications in promising fields.
Collapse
Affiliation(s)
- Rijun Gui
- College of Chemistry and Chemical Engineering, Intellectual Property Research Institute, Qingdao University, Shandong, 266071, PR China.
| | - Hui Jin
- College of Chemistry and Chemical Engineering, Intellectual Property Research Institute, Qingdao University, Shandong, 266071, PR China
| |
Collapse
|
2
|
Li SA, Meng XY, Zhang YJ, Chen CL, Jiao YX, Zhu YQ, Liu PP, Sun W. Progress in pH-Sensitive sensors: essential tools for organelle pH detection, spotlighting mitochondrion and diverse applications. Front Pharmacol 2024; 14:1339518. [PMID: 38269286 PMCID: PMC10806205 DOI: 10.3389/fphar.2023.1339518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024] Open
Abstract
pH-sensitive fluorescent proteins have revolutionized the field of cellular imaging and physiology, offering insight into the dynamic pH changes that underlie fundamental cellular processes. This comprehensive review explores the diverse applications and recent advances in the use of pH-sensitive fluorescent proteins. These remarkable tools enable researchers to visualize and monitor pH variations within subcellular compartments, especially mitochondria, shedding light on organelle-specific pH regulation. They play pivotal roles in visualizing exocytosis and endocytosis events in synaptic transmission, monitoring cell death and apoptosis, and understanding drug effects and disease progression. Recent advancements have led to improved photostability, pH specificity, and subcellular targeting, enhancing their utility. Techniques for multiplexed imaging, three-dimensional visualization, and super-resolution microscopy are expanding the horizon of pH-sensitive protein applications. The future holds promise for their integration into optogenetics and drug discovery. With their ever-evolving capabilities, pH-sensitive fluorescent proteins remain indispensable tools for unravelling cellular dynamics and driving breakthroughs in biological research. This review serves as a comprehensive resource for researchers seeking to harness the potential of pH-sensitive fluorescent proteins.
Collapse
Affiliation(s)
- Shu-Ang Li
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiao-Yan Meng
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ying-Jie Zhang
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Cai-Li Chen
- Department of Immunology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yu-Xue Jiao
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yong-Qing Zhu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Pei-Pei Liu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Wei Sun
- Department of Burn and Repair Reconstruction, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| |
Collapse
|
3
|
Giuraniuc CV, Parkin C, Almeida MC, Fricker M, Shadmani P, Nye S, Wehmeier S, Chawla S, Bedekovic T, Lehtovirta-Morley L, Richards DM, Gow NA, Brand AC. Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans. mBio 2023; 14:e0115723. [PMID: 37750683 PMCID: PMC10653887 DOI: 10.1128/mbio.01157-23] [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: 05/09/2023] [Accepted: 08/07/2023] [Indexed: 09/27/2023] Open
Abstract
IMPORTANCE Intracellular calcium signaling plays an important role in the resistance and adaptation to stresses encountered by fungal pathogens within the host. This study reports the optimization of the GCaMP fluorescent calcium reporter for live-cell imaging of dynamic calcium responses in single cells of the pathogen, Candida albicans, for the first time. Exposure to membrane, osmotic or oxidative stress generated both specific changes in single cell intracellular calcium spiking and longer calcium transients across the population. Repeated treatments showed that calcium dynamics become unaffected by some stresses but not others, consistent with known cell adaptation mechanisms. By expressing GCaMP in mutant strains and tracking the viability of individual cells over time, the relative contributions of key signaling pathways to calcium flux, stress adaptation, and cell death were demonstrated. This reporter, therefore, permits the study of calcium dynamics, homeostasis, and signaling in C. albicans at a previously unattainable level of detail.
Collapse
Affiliation(s)
- C. V. Giuraniuc
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - C. Parkin
- MRC Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom
| | - M. C. Almeida
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - M. Fricker
- School of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - P. Shadmani
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - S. Nye
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - S. Wehmeier
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - S. Chawla
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - T. Bedekovic
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
- MRC Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom
| | - L. Lehtovirta-Morley
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - D. M. Richards
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
- Department of Physics and Astronomy, University of Exeter, Exeter, United Kingdom
| | - N. A. Gow
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
- MRC Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom
| | - A. C. Brand
- School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
- MRC Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| |
Collapse
|
4
|
Žunar B, Ito T, Mosrin C, Sugahara Y, Bénédetti H, Guégan R, Vallée B. Confocal imaging of biomarkers at a single-cell resolution: quantifying 'living' in 3D-printable engineered living material based on Pluronic F-127 and yeast Saccharomyces cerevisiae. Biomater Res 2022; 26:85. [PMID: 36539854 PMCID: PMC9769040 DOI: 10.1186/s40824-022-00337-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Engineered living materials (ELMs) combine living cells with non-living scaffolds to obtain life-like characteristics, such as biosensing, growth, and self-repair. Some ELMs can be 3D-printed and are called bioinks, and their scaffolds are mostly hydrogel-based. One such scaffold is polymer Pluronic F127, a liquid at 4 °C but a biocompatible hydrogel at room temperature. In such thermally-reversible hydrogel, the microorganism-hydrogel interactions remain uncharacterized, making truly durable 3D-bioprinted ELMs elusive. METHODS We demonstrate the methodology to assess cell-scaffold interactions by characterizing intact alive yeast cells in cross-linked F127-based hydrogels, using genetically encoded ratiometric biosensors to measure intracellular ATP and cytosolic pH at a single-cell level through confocal imaging. RESULTS When embedded in hydrogel, cells were ATP-rich, in exponential or stationary phase, and assembled into microcolonies, which sometimes merged into larger superstructures. The hydrogels supported (micro)aerobic conditions and induced a nutrient gradient that limited microcolony size. External compounds could diffuse at least 2.7 mm into the hydrogels, although for optimal yeast growth bioprinted structures should be thinner than 0.6 mm. Moreover, the hydrogels could carry whole-cell copper biosensors, shielding them from contaminations and providing them with nutrients. CONCLUSIONS F127-based hydrogels are promising scaffolds for 3D-bioprinted ELMs, supporting a heterogeneous cell population primarily shaped by nutrient availability.
Collapse
Affiliation(s)
- Bojan Žunar
- Centre de Biophysique Moléculaire (CBM), CNRS, UPR 4301, University of Orléans and INSERM, 45071, Orléans, Cedex 2, France
- Department of Chemistry and Biochemistry, Laboratory for Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Taiga Ito
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555, Japan
| | - Christine Mosrin
- Centre de Biophysique Moléculaire (CBM), CNRS, UPR 4301, University of Orléans and INSERM, 45071, Orléans, Cedex 2, France
| | - Yoshiyuki Sugahara
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555, Japan
| | - Hélène Bénédetti
- Centre de Biophysique Moléculaire (CBM), CNRS, UPR 4301, University of Orléans and INSERM, 45071, Orléans, Cedex 2, France
| | - Régis Guégan
- Global Center for Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555, Japan
- Institut des Sciences de la Terre d'Orléans (ISTO), UMR 7327, CNRS-Université d'Orléans, 1A Rue de la Férollerie, 45071, Orléans, Cedex 2, France
| | - Béatrice Vallée
- Centre de Biophysique Moléculaire (CBM), CNRS, UPR 4301, University of Orléans and INSERM, 45071, Orléans, Cedex 2, France.
| |
Collapse
|
5
|
Hu WH, Zhou K, Liu L, Wu HC. Construction of a pH-Mediated Single-Molecule Switch with a Nanopore-DNA Complex. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2201650. [PMID: 35723176 DOI: 10.1002/smll.202201650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/16/2022] [Indexed: 06/15/2023]
Abstract
A molecular switch is one of the simplest examples of artificial molecular machines. Even so, the development of molecular switches is still at its very early stage. Currently, building single-molecule switches mostly rely on the molecular junction technique, but many of their performance characteristics are device-dependent. Here, a pH-mediated single-molecule switch based on the combination of an α-hemolysin (αHL) nanopore and a hexacyclen-modified DNA strand is developed. The single-stranded DNA is suspended inside an αHL through biotin-streptavidin linkage and the hexacyclen-modified nucleobase interacts with amino acid residues at positions 111, 113, and 147 to cause current oscillations. Distinct current transitions are observed when pH is tuned back and forth in the range of 3.0-7.4, with a typical "up" level when pH > 6.5 and a "down" level when pH < 4.5. This nanopore-DNA complex possesses membrane-bound advantages and may find applications in single-cell studies where pH could be readily tuned to control ON-OFF functions.
Collapse
Affiliation(s)
- Wei-Hu Hu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ke Zhou
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lei Liu
- Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Hai-Chen Wu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| |
Collapse
|
6
|
Hartmann FSF, Udugama IA, Seibold GM, Sugiyama H, Gernaey KV. Digital models in biotechnology: Towards multi-scale integration and implementation. Biotechnol Adv 2022; 60:108015. [PMID: 35781047 DOI: 10.1016/j.biotechadv.2022.108015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/03/2022] [Accepted: 06/27/2022] [Indexed: 12/28/2022]
Abstract
Industrial biotechnology encompasses a large area of multi-scale and multi-disciplinary research activities. With the recent megatrend of digitalization sweeping across all industries, there is an increased focus in the biotechnology industry on developing, integrating and applying digital models to improve all aspects of industrial biotechnology. Given the rapid development of this field, we systematically classify the state-of-art modelling concepts applied at different scales in industrial biotechnology and critically discuss their current usage, advantages and limitations. Further, we critically analyzed current strategies to couple cell models with computational fluid dynamics to study the performance of industrial microorganisms in large-scale bioprocesses, which is of crucial importance for the bio-based production industries. One of the most challenging aspects in this context is gathering intracellular data under industrially relevant conditions. Towards comprehensive models, we discuss how different scale-down concepts combined with appropriate analytical tools can capture intracellular states of single cells. We finally illustrated how the efforts could be used to develop digitals models suitable for both cell factory design and process optimization at industrial scales in the future.
Collapse
Affiliation(s)
- Fabian S F Hartmann
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 223, 2800 Kgs. Lyngby, Denmark
| | - Isuru A Udugama
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan; Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 228 A, 2800 Kgs. Lyngby, Denmark.
| | - Gerd M Seibold
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 223, 2800 Kgs. Lyngby, Denmark
| | - Hirokazu Sugiyama
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan
| | - Krist V Gernaey
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 228 A, 2800 Kgs. Lyngby, Denmark.
| |
Collapse
|
7
|
Karsten L, Goett-Zink L, Schmitz J, Hoffrogge R, Grünberger A, Kottke T, Müller KM. Genetically Encoded Ratiometric pH Sensors for the Measurement of Intra- and Extracellular pH and Internalization Rates. BIOSENSORS 2022; 12:bios12050271. [PMID: 35624572 PMCID: PMC9138566 DOI: 10.3390/bios12050271] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022]
Abstract
pH-sensitive fluorescent proteins as genetically encoded pH sensors are promising tools for monitoring intra- and extracellular pH. However, there is a lack of ratiometric pH sensors, which offer a good dynamic range and can be purified and applied extracellularly to investigate uptake. In our study, the bright fluorescent protein CoGFP_V0 was C-terminally fused to the ligand epidermal growth factor (EGF) and retained its dual-excitation and dual-emission properties as a purified protein. The tandem fluorescent variants EGF-CoGFP-mTagBFP2 (pK′ = 6.6) and EGF-CoGFP-mCRISPRed (pK′ = 6.1) revealed high dynamic ranges between pH 4.0 and 7.5. Using live-cell fluorescence microscopy, both pH sensor molecules permitted the conversion of fluorescence intensity ratios to detailed intracellular pH maps, which revealed pH gradients within endocytic vesicles. Additionally, extracellular binding of the pH sensors to cells expressing the EGF receptor (EGFR) enabled the tracking of pH shifts inside cultivation chambers of a microfluidic device. Furthermore, the dual-emission properties of EGF-CoGFP-mCRISPRed upon 488 nm excitation make this pH sensor a valuable tool for ratiometric flow cytometry. This high-throughput method allowed for the determination of internalization rates, which represents a promising kinetic parameter for the in vitro characterization of protein–drug conjugates in cancer therapy.
Collapse
Affiliation(s)
- Lennard Karsten
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Lukas Goett-Zink
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Julian Schmitz
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Raimund Hoffrogge
- Cell Culture Technology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Alexander Grünberger
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Tilman Kottke
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Kristian M. Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
- Correspondence:
| |
Collapse
|
8
|
Liu H, Zhou P, Qi M, Guo L, Gao C, Hu G, Song W, Wu J, Chen X, Chen J, Chen W, Liu L. Enhancing biofuels production by engineering the actin cytoskeleton in Saccharomyces cerevisiae. Nat Commun 2022; 13:1886. [PMID: 35393407 PMCID: PMC8991263 DOI: 10.1038/s41467-022-29560-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/23/2022] [Indexed: 01/03/2023] Open
Abstract
Saccharomyces cerevisiae is widely employed as a cell factory for the production of biofuels. However, product toxicity has hindered improvements in biofuel production. Here, we engineer the actin cytoskeleton in S. cerevisiae to increase both the cell growth and production of n-butanol and medium-chain fatty acids. Actin cable tortuosity is regulated using an n-butanol responsive promoter-based autonomous bidirectional signal conditioner in S. cerevisiae. The budding index is increased by 14.0%, resulting in the highest n-butanol titer of 1674.3 mg L-1. Moreover, actin patch density is fine-tuned using a medium-chain fatty acid responsive promoter-based autonomous bidirectional signal conditioner. The intracellular pH is stabilized at 6.4, yielding the highest medium-chain fatty acids titer of 692.3 mg L-1 in yeast extract peptone dextrose medium. Engineering the actin cytoskeleton in S. cerevisiae can efficiently alleviate biofuels toxicity and enhance biofuels production.
Collapse
Affiliation(s)
- Hui Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Pei Zhou
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Mengya Qi
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Liang Guo
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Cong Gao
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Guipeng Hu
- School of Pharmaceutical Science, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
| | - Wei Song
- School of Pharmaceutical Science, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
| | - Jing Wu
- School of Pharmaceutical Science, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
| | - Xiulai Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jian Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Liming Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
| |
Collapse
|
9
|
In Vivo Monitoring of Cytosolic pH Using the Ratiometric pH Sensor pHluorin. Methods Mol Biol 2022; 2391:99-107. [PMID: 34686980 DOI: 10.1007/978-1-0716-1795-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cytosolic pH (pHcyt) is a key factor controlling cell fate. The genetically encoded pH-sensor pHluorin has proven highly valuable for studies on pHcyt in many living organisms. pHluorin displays a bimodal excitation spectrum with peaks at 395 nm and 475 nm, which is dependent on pH. Here we describe two different protocols for determining pHcyt in the soil-borne fungal pathogen Fusarium oxysporum, based either on population or single-cell analysis.
Collapse
|
10
|
Van Genechten W, Van Dijck P, Demuyser L. Fluorescent toys 'n' tools lighting the way in fungal research. FEMS Microbiol Rev 2021; 45:fuab013. [PMID: 33595628 PMCID: PMC8498796 DOI: 10.1093/femsre/fuab013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/14/2021] [Indexed: 12/13/2022] Open
Abstract
Although largely overlooked compared to bacterial infections, fungal infections pose a significant threat to the health of humans and other organisms. Many pathogenic fungi, especially Candida species, are extremely versatile and flexible in adapting to various host niches and stressful situations. This leads to high pathogenicity and increasing resistance to existing drugs. Due to the high level of conservation between fungi and mammalian cells, it is hard to find fungus-specific drug targets for novel therapy development. In this respect, it is vital to understand how these fungi function on a molecular, cellular as well as organismal level. Fluorescence imaging allows for detailed analysis of molecular mechanisms, cellular structures and interactions on different levels. In this manuscript, we provide researchers with an elaborate and contemporary overview of fluorescence techniques that can be used to study fungal pathogens. We focus on the available fluorescent labelling techniques and guide our readers through the different relevant applications of fluorescent imaging, from subcellular events to multispecies interactions and diagnostics. As well as cautioning researchers for potential challenges and obstacles, we offer hands-on tips and tricks for efficient experimentation and share our expert-view on future developments and possible improvements.
Collapse
Affiliation(s)
- Wouter Van Genechten
- VIB-KU Leuven Center for Microbiology, Kasteelpark Arenberg 31, 3001 Leuven-heverlee, Belgium
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Kasteelpark Arenberg 31, 3001 Leuven-Heverlee, Belgium
- Laboratory for Nanobiology, Department of Chemistry, KU Leuven, Celestijnenlaan 200g, 3001 Leuven-Heverlee, Belgium
| | - Patrick Van Dijck
- VIB-KU Leuven Center for Microbiology, Kasteelpark Arenberg 31, 3001 Leuven-heverlee, Belgium
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Kasteelpark Arenberg 31, 3001 Leuven-Heverlee, Belgium
| | - Liesbeth Demuyser
- VIB-KU Leuven Center for Microbiology, Kasteelpark Arenberg 31, 3001 Leuven-heverlee, Belgium
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Kasteelpark Arenberg 31, 3001 Leuven-Heverlee, Belgium
| |
Collapse
|
11
|
Differential Effect of Extracellular Acidic Environment on IL-1β Released from Human and Mouse Phagocytes. Int J Mol Sci 2020; 21:ijms21197229. [PMID: 33007998 PMCID: PMC7582253 DOI: 10.3390/ijms21197229] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/21/2020] [Accepted: 09/28/2020] [Indexed: 02/06/2023] Open
Abstract
Areas of locally decreased pH are characteristic for many chronic inflammatory diseases such as atherosclerosis and rheumatoid arthritis, acute pathologies such as ischemia reperfusion, and tumor microenvironment. The data on the effects of extracellular acidic pH on inflammation are conflicting with respect to interleukin 1 beta (IL-1β) as one of the most potent proinflammatory cytokines. In this study, we used various mouse- and human-derived cells in order to identify potential species-specific differences in IL-1β secretion pattern in response to extracellular acidification. We found that a short incubation in mild acidic medium caused significant IL-1β release from human macrophages, however, the same effect was not observed in mouse macrophages. Rather, a marked IL-1β suppression was observed when mouse cells were stimulated with a combination of various inflammasome instigators and low pH. Upon activation of cells under acidic conditions, the cytosolic pH was reduced while metabolic activity and the expression of the main inflammasome proteins were not affected by low pH. We show that IL-1β secretion in mouse macrophages is reversible upon restoration of physiological pH. pH sensitivity of NLRP3, NLRC4 and AIM2 inflammasomes appeared to be conferred by the processes upstream of the apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization and most likely contributed by the cell background rather than species-specific amino acid sequences of the sensor proteins.
Collapse
|
12
|
Triandafillou CG, Katanski CD, Dinner AR, Drummond DA. Transient intracellular acidification regulates the core transcriptional heat shock response. eLife 2020; 9:e54880. [PMID: 32762843 PMCID: PMC7449696 DOI: 10.7554/elife.54880] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 08/07/2020] [Indexed: 01/18/2023] Open
Abstract
Heat shock induces a conserved transcriptional program regulated by heat shock factor 1 (Hsf1) in eukaryotic cells. Activation of this heat shock response is triggered by heat-induced misfolding of newly synthesized polypeptides, and so has been thought to depend on ongoing protein synthesis. Here, using the budding yeast Saccharomyces cerevisiae, we report the discovery that Hsf1 can be robustly activated when protein synthesis is inhibited, so long as cells undergo cytosolic acidification. Heat shock has long been known to cause transient intracellular acidification which, for reasons which have remained unclear, is associated with increased stress resistance in eukaryotes. We demonstrate that acidification is required for heat shock response induction in translationally inhibited cells, and specifically affects Hsf1 activation. Physiological heat-triggered acidification also increases population fitness and promotes cell cycle reentry following heat shock. Our results uncover a previously unknown adaptive dimension of the well-studied eukaryotic heat shock response.
Collapse
Affiliation(s)
| | - Christopher D Katanski
- Department of Biochemistry and Molecular Biology and Department of Medicine, Section of Genetic Medicine, The University of ChicagoChicagoUnited States
| | - Aaron R Dinner
- Department of Chemistry and the James Franck Institute, The University of ChicagoChicagoUnited States
| | - D Allan Drummond
- Department of Biochemistry and Molecular Biology and Department of Medicine, Section of Genetic Medicine, The University of ChicagoChicagoUnited States
| |
Collapse
|
13
|
Triandafillou CG, Drummond DA. Live Cell Measurement of the Intracellular pH of Yeast by Flow Cytometry Using a Genetically-Encoded Fluorescent Reporter. Bio Protoc 2020; 10:e3653. [PMID: 33659323 DOI: 10.21769/bioprotoc.3653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/23/2020] [Accepted: 03/18/2020] [Indexed: 11/02/2022] Open
Abstract
The intracellular pH of yeast is a tightly regulated physiological cue that changes in response to growth state and environmental conditions. Fluorescent reporters, which have altered fluorescence in response to local pH changes, can be used to measure intracellular pH. While microscopy is often used to make such measurements, it is relatively low-throughput such that collecting enough data to fully characterize populations of cells is challenging. Flow cytometry avoids this drawback, and is a powerful tool that allows for rapid, high-throughput measurement of fluorescent readouts in individual cells. When combined with pH-sensitive fluorescent reporters, it can be used to characterize the intracellular pH of large populations of cells at the single-cell level. We adapted microscopy and flow-cytometry based methods to measure the intracellular pH of yeast. Cells can be grown under near-native conditions up until the point of measurement, and the protocol can be adapted to single-point or dynamic (time-resolved) measurements during changing environmental conditions.
Collapse
Affiliation(s)
| | - D Allan Drummond
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, USA.,Department of Human Genetics, University of Chicago, Chicago, USA
| |
Collapse
|
14
|
Kostyuk AI, Kokova AD, Podgorny OV, Kelmanson IV, Fetisova ES, Belousov VV, Bilan DS. Genetically Encoded Tools for Research of Cell Signaling and Metabolism under Brain Hypoxia. Antioxidants (Basel) 2020; 9:E516. [PMID: 32545356 PMCID: PMC7346190 DOI: 10.3390/antiox9060516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 02/08/2023] Open
Abstract
Hypoxia is characterized by low oxygen content in the tissues. The central nervous system (CNS) is highly vulnerable to a lack of oxygen. Prolonged hypoxia leads to the death of brain cells, which underlies the development of many pathological conditions. Despite the relevance of the topic, different approaches used to study the molecular mechanisms of hypoxia have many limitations. One promising lead is the use of various genetically encoded tools that allow for the observation of intracellular parameters in living systems. In the first part of this review, we provide the classification of oxygen/hypoxia reporters as well as describe other genetically encoded reporters for various metabolic and redox parameters that could be implemented in hypoxia studies. In the second part, we discuss the advantages and disadvantages of the primary hypoxia model systems and highlight inspiring examples of research in which these experimental settings were combined with genetically encoded reporters.
Collapse
Affiliation(s)
- Alexander I. Kostyuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Aleksandra D. Kokova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Oleg V. Podgorny
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Koltzov Institute of Developmental Biology, 119334 Moscow, Russia
| | - Ilya V. Kelmanson
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Elena S. Fetisova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Vsevolod V. Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Institute for Cardiovascular Physiology, Georg August University Göttingen, D-37073 Göttingen, Germany
- Federal Center for Cerebrovascular Pathology and Stroke, 117997 Moscow, Russia
| | - Dmitry S. Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| |
Collapse
|
15
|
Heins AL, Weuster-Botz D. Population heterogeneity in microbial bioprocesses: origin, analysis, mechanisms, and future perspectives. Bioprocess Biosyst Eng 2018. [PMID: 29541890 DOI: 10.1007/s00449-018-1922-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Population heterogeneity is omnipresent in all bioprocesses even in homogenous environments. Its origin, however, is only so well understood that potential strategies like bet-hedging, noise in gene expression and division of labour that lead to population heterogeneity can be derived from experimental studies simulating the dynamics in industrial scale bioprocesses. This review aims at summarizing the current state of the different parts of single cell studies in bioprocesses. This includes setups to visualize different phenotypes of single cells, computational approaches connecting single cell physiology with environmental influence and special cultivation setups like scale-down reactors that have been proven to be useful to simulate large-scale conditions. A step in between investigation of populations and single cells is studying subpopulations with distinct properties that differ from the rest of the population with sub-omics methods which are also presented here. Moreover, the current knowledge about population heterogeneity in bioprocesses is summarized for relevant industrial production hosts and mixed cultures, as they provide the unique opportunity to distribute metabolic burden and optimize production processes in a way that is impossible in traditional monocultures. In the end, approaches to explain the underlying mechanism of population heterogeneity and the evidences found to support each hypothesis are presented. For instance, population heterogeneity serving as a bet-hedging strategy that is used as coordinated action against bioprocess-related stresses while at the same time spreading the risk between individual cells as it ensures the survival of least a part of the population in any environment the cells encounter.
Collapse
Affiliation(s)
- Anna-Lena Heins
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany.
| | - Dirk Weuster-Botz
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
| |
Collapse
|
16
|
Adam K, Hunter T. Histidine kinases and the missing phosphoproteome from prokaryotes to eukaryotes. J Transl Med 2018; 98:233-247. [PMID: 29058706 PMCID: PMC5815933 DOI: 10.1038/labinvest.2017.118] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/16/2017] [Accepted: 08/31/2017] [Indexed: 12/20/2022] Open
Abstract
Protein phosphorylation is the most common type of post-translational modification in eukaryotes. The phosphoproteome is defined as the complete set of experimentally detectable phosphorylation sites present in a cell's proteome under various conditions. However, we are still far from identifying all the phosphorylation sites in a cell mainly due to the lack of information about phosphorylation events involving residues other than Ser, Thr and Tyr. Four types of phosphate-protein linkage exist and these generate nine different phosphoresidues-pSer, pThr, pTyr, pHis, pLys, pArg, pAsp, pGlu and pCys. Most of the effort in studying protein phosphorylation has been focused on Ser, Thr and Tyr phosphorylation. The recent development of 1- and 3-pHis monoclonal antibodies promises to increase our understanding of His phosphorylation and the kinases and phosphatases involved. Several His kinases are well defined in prokaryotes, especially those involved in two-component system (TCS) signaling. However, in higher eukaryotes, NM23, a protein originally characterized as a nucleoside diphosphate kinase, is the only characterized protein-histidine kinase. This ubiquitous and conserved His kinase autophosphorylates its active site His, and transfers this phosphate either onto a nucleoside diphosphate or onto a protein His residue. Studies of NM23 protein targets using newly developed anti-pHis antibodies will surely help illuminate the elusive His phosphorylation-based signaling pathways. This review discusses the role that the NM23/NME/NDPK phosphotransferase has, how the addition of the pHis phosphoproteome will expand the phosphoproteome and make His phosphorylation part of the global phosphorylation world. It also summarizes why our understanding of phosphorylation is still largely restricted to the acid stable phosphoproteome, and highlights the study of NM23 histidine kinase as an entrée into the world of histidine phosphorylation.
Collapse
Affiliation(s)
- Kevin Adam
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| |
Collapse
|
17
|
Rosenthal K, Oehling V, Dusny C, Schmid A. Beyond the bulk: disclosing the life of single microbial cells. FEMS Microbiol Rev 2017; 41:751-780. [PMID: 29029257 PMCID: PMC5812503 DOI: 10.1093/femsre/fux044] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 09/08/2017] [Indexed: 01/08/2023] Open
Abstract
Microbial single cell analysis has led to discoveries that are beyond what can be resolved with population-based studies. It provides a pristine view of the mechanisms that organize cellular physiology, unbiased by population heterogeneity or uncontrollable environmental impacts. A holistic description of cellular functions at the single cell level requires analytical concepts beyond the miniaturization of existing technologies, defined but uncontrolled by the biological system itself. This review provides an overview of the latest advances in single cell technologies and demonstrates their potential. Opportunities and limitations of single cell microbiology are discussed using selected application-related examples.
Collapse
Affiliation(s)
- Katrin Rosenthal
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Verena Oehling
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Christian Dusny
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
| | - Andreas Schmid
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
| |
Collapse
|
18
|
Elsutohy MM, Chauhan VM, Markus R, Kyyaly MA, Tendler SJB, Aylott JW. Real-time measurement of the intracellular pH of yeast cells during glucose metabolism using ratiometric fluorescent nanosensors. NANOSCALE 2017; 9:5904-5911. [PMID: 28436517 DOI: 10.1039/c7nr00906b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intracellular pH is a key parameter that influences many biochemical and metabolic pathways that can also be used as an indirect marker to monitor metabolic and intracellular processes. Herein, we utilise ratiometric fluorescent pH-sensitive nanosensors with an extended dynamic pH range to measure the intracellular pH of yeast (Saccharomyces cerevisiae) during glucose metabolism in real-time. Ratiometric fluorescent pH-sensitive nanosensors consisting of a polyacrylamide nanoparticle matrix covalently linked to two pH-sensitive fluorophores, Oregon green (OG) and 5(6)carboxyfluorescein (FAM), and a reference pH-insensitive fluorophore, 5(6)carboxytetramethylrhodamine (TAMRA), were synthesised. Nanosensors were functionalised with acrylamidopropyltrimethyl ammonium hydrochloride (ACTA) to confer a positive charge to the nanoparticle surfaces that facilitated nanosensor delivery to yeast cells, negating the need to use stress inducing techniques. The results showed that under glucose-starved conditions the intracellular pH of yeast population (n ≈ 200) was 4.67 ± 0.15. Upon addition of d-(+)-glucose (10 mM), this pH value decreased to pH 3.86 ± 0.13 over a period of 10 minutes followed by a gradual rise to a maximal pH of 5.21 ± 0.26, 25 minutes after glucose addition. 45 minutes after the addition of glucose, the intracellular pH of yeast cells returned to that of the glucose starved conditions. This study advances our understanding of the interplay between glucose metabolism and pH regulation in yeast cells, and indicates that the intracellular pH homestasis in yeast is highly regulated and demonstrates the utility of nanosensors for real-time intracellular pH measurements.
Collapse
Affiliation(s)
- Mohamed M Elsutohy
- School of Pharmacy, Boots Science Building, University of Nottingham, Nottingham, NG7 2RD, UK.
| | | | | | | | | | | |
Collapse
|
19
|
Narayanan V, Schelin J, Gorwa-Grauslund M, van Niel EWJ, Carlquist M. Increased lignocellulosic inhibitor tolerance of Saccharomyces cerevisiae cell populations in early stationary phase. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:114. [PMID: 28484514 PMCID: PMC5418707 DOI: 10.1186/s13068-017-0794-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 04/18/2017] [Indexed: 05/23/2023]
Abstract
BACKGROUND Production of second-generation bioethanol and other bulk chemicals by yeast fermentation requires cells that tolerate inhibitory lignocellulosic compounds at low pH. Saccharomyces cerevisiae displays high plasticity with regard to inhibitor tolerance, and adaptation of cell populations to process conditions is essential for reaching efficient and robust fermentations. RESULTS In this study, we assessed responses of isogenic yeast cell populations in different physiological states to combinations of acetic acid, vanillin and furfural at low pH. We found that cells in early stationary phase (ESP) exhibited significantly increased tolerance compared to cells in logarithmic phase, and had a similar ability to initiate growth in the presence of inhibitors as pre-adapted cells. The ESP cultures consisted of subpopulations with different buoyant cell densities which were isolated with flotation and analysed separately. These so-called quiescent (Q) and non-quiescent (NQ) cells were found to possess similar abilities to initiate growth in the presence of lignocellulosic inhibitors at pH 3.7, and had similar viabilities under static conditions. Therefore, differentiation into Q-cells was not the cause for increased tolerance of ESP cultures. Flow cytometry analysis of cell viability, intracellular pH and reactive oxygen species levels revealed that tolerant cell populations had a characteristic response upon inhibitor perturbations. Growth in the presence of a combination of inhibitors at low pH correlated with pre-cultures having a high frequency of cells with low pHi and low ROS levels. Furthermore, only a subpopulation of ESP cultures was able to tolerate lignocellulosic inhibitors at low pH, while pre-adapted cell populations displayed an almost uniform high tolerance to the adverse condition. This was in stark contrast to cell populations growing exponentially in non-inhibitory medium that were uniformly sensitive to the inhibitors at low pH. CONCLUSIONS ESP cultures of S. cerevisiae were found to have high tolerance to lignocellulosic inhibitors at low pH, and were able to initiate growth to the same degree as cells that were pre-adapted to inhibitors at a slightly acidic pH. Carbon starvation may thus be a potential strategy to prepare cell populations for adjacent stressful environments which may be beneficial from a process perspective for fermentation of non-detoxified lignocellulosic substrates at low pH. Furthermore, flow cytometry analysis of pHi and ROS level distributions in ESP cultures revealed responses that were characteristic for populations with high tolerance to lignocellulosic inhibitors. Measurement of population distribution responses as described herein may be applied to predict the outcome of environmental perturbations and thus can function as feedback for process control of yeast fitness during lignocellulosic fermentation.
Collapse
Affiliation(s)
- Venkatachalam Narayanan
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Marie Gorwa-Grauslund
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Ed WJ van Niel
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Magnus Carlquist
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| |
Collapse
|
20
|
Weber N, Gorwa-Grauslund M, Carlquist M. Improvement of whole-cell transamination with Saccharomyces cerevisiae using metabolic engineering and cell pre-adaptation. Microb Cell Fact 2017; 16:3. [PMID: 28049528 PMCID: PMC5209827 DOI: 10.1186/s12934-016-0615-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/09/2016] [Indexed: 01/27/2023] Open
Abstract
Background Whole-cell biocatalysis based on metabolically active baker’s yeast with engineered transamination activity can be used to generate molecules carrying a chiral amine moiety. A prerequisite is though to express efficient ω-transaminases and to reach sufficient intracellular precursor levels. Results Herein, the efficiency of three different ω-transaminases originating from Capsicum chinense, Chromobacterium violaceum, and Ochrobactrum anthropi was compared for whole-cell catalyzed kinetic resolution of racemic 1-phenylethylamine to (R)-1-phenylethylamine. The gene from the most promising candidate, C. violaceum ω-transaminase (CV-TA), was expressed in a strain lacking pyruvate decarboxylase activity, which thereby accumulate the co-substrate pyruvate during glucose assimilation. However, the conversion increased only slightly under the applied reaction conditions. In parallel, the effect of increasing the intracellular pyridoxal-5′-phosphate (PLP) level by omission of thiamine during cultivation was investigated. It was found that without thiamine, PLP supplementation was redundant to keep high in vivo transamination activity. Furthermore, higher reaction rates were achieved using a strain containing several copies of CV-TA gene, highlighting the necessity to also increase the intracellular transaminase level. At last, this strain was also investigated for asymmetric whole-cell bioconversion of acetophenone to (S)-1-phenylethylamine using l-alanine as amine donor. Although functionality could be demonstrated, the activity was extremely low indicating that the native co-product removal system was unable to drive the reaction towards the amine under the applied reaction conditions. Conclusions Altogether, our results demonstrate that (R)-1-phenylethylamine with >99% ee can be obtained via kinetic resolution at concentrations above 25 mM racemic substrate with glucose as sole co-substrate when combining appropriate genetic and process engineering approaches. Furthermore, the engineered yeast strain with highest transaminase activity was also shown to be operational as whole-cell catalyst for the production of (S)-1-phenylethylamine via asymmetric transamination of acetophenone, albeit with very low conversion. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0615-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Nora Weber
- Division of Applied Microbiology, Department of Chemistry, Faculty of Engineering, Lund University, PO Box 124, 221 00, Lund, Sweden.,Evolva SA, Duggingerstrasse 23, 4153, Reinach, Switzerland
| | - Marie Gorwa-Grauslund
- Division of Applied Microbiology, Department of Chemistry, Faculty of Engineering, Lund University, PO Box 124, 221 00, Lund, Sweden
| | - Magnus Carlquist
- Division of Applied Microbiology, Department of Chemistry, Faculty of Engineering, Lund University, PO Box 124, 221 00, Lund, Sweden.
| |
Collapse
|
21
|
Lee JW, In JH, Park JB, Shin J, Park JH, Sung BH, Sohn JH, Seo JH, Park JB, Kim SR, Kweon DH. Co-expression of two heterologous lactate dehydrogenases genes in Kluyveromyces marxianus for l-lactic acid production. J Biotechnol 2016; 241:81-86. [PMID: 27867078 DOI: 10.1016/j.jbiotec.2016.11.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/10/2016] [Accepted: 11/16/2016] [Indexed: 11/18/2022]
Abstract
Lactic acid (LA) is a versatile compound used in the food, pharmaceutical, textile, leather, and chemical industries. Biological production of LA is possible by yeast strains expressing a bacterial gene encoding l-lactate dehydrogenase (LDH). Kluyveromyces marxianus is an emerging non-conventional yeast with various phenotypes of industrial interest. However, it has not been extensively studied for LA production. In this study, K. marxianus was engineered to express and co-express various heterologous LDH enzymes that were reported to have different pH optimums. Specifically, three LDH enzymes originating from Staphylococcus epidermidis (SeLDH; optimal at pH 5.6), Lactobacillus acidophilus (LaLDH; optimal at pH 5.3), and Bos taurus (BtLDH; optimal at pH 9.8) were functionally expressed individually and in combination in K. marxianus, and the resulting strains were compared in terms of LA production. A strain co-expressing SeLDH and LaLDH (KM5 La+SeLDH) produced 16.0g/L LA, whereas the strains expressing those enzymes individually produced only 8.4 and 6.8g/L, respectively. This co-expressing strain produced 24.0g/L LA with a yield of 0.48g/g glucose in the presence of CaCO3. Our results suggest that co-expression of LDH enzymes with different pH optimums provides sufficient LDH activity under dynamic intracellular pH conditions, leading to enhanced production of LA compared to individual expression of the LDH enzymes.
Collapse
Affiliation(s)
- Jae Won Lee
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Jung Hoon In
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Joon-Bum Park
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Jonghyeok Shin
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Jin Hwan Park
- Biomaterials Lab, Samsung Advanced Institute of Technology, Yongin 446-712, Republic of Korea
| | - Bong Hyun Sung
- Korea Research Institute of Bioscience & Biotechnology, Daejeon 305-806, Republic of Korea
| | - Jung-Hoon Sohn
- Korea Research Institute of Bioscience & Biotechnology, Daejeon 305-806, Republic of Korea
| | - Jin-Ho Seo
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
| | - Jin-Byoung Park
- Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Soo Rin Kim
- School of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kyungpook National University, 702-701, Republic of Korea.
| | - Dae-Hyuk Kweon
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
| |
Collapse
|
22
|
pH determines the energetic efficiency of the cyanobacterial CO2 concentrating mechanism. Proc Natl Acad Sci U S A 2016; 113:E5354-62. [PMID: 27551079 DOI: 10.1073/pnas.1525145113] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Many carbon-fixing bacteria rely on a CO2 concentrating mechanism (CCM) to elevate the CO2 concentration around the carboxylating enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO). The CCM is postulated to simultaneously enhance the rate of carboxylation and minimize oxygenation, a competitive reaction with O2 also catalyzed by RuBisCO. To achieve this effect, the CCM combines two features: active transport of inorganic carbon into the cell and colocalization of carbonic anhydrase and RuBisCO inside proteinaceous microcompartments called carboxysomes. Understanding the significance of the various CCM components requires reconciling biochemical intuition with a quantitative description of the system. To this end, we have developed a mathematical model of the CCM to analyze its energetic costs and the inherent intertwining of physiology and pH. We find that intracellular pH greatly affects the cost of inorganic carbon accumulation. At low pH the inorganic carbon pool contains more of the highly cell-permeable H2CO3, necessitating a substantial expenditure of energy on transport to maintain internal inorganic carbon levels. An intracellular pH ≈8 reduces leakage, making the CCM significantly more energetically efficient. This pH prediction coincides well with our measurement of intracellular pH in a model cyanobacterium. We also demonstrate that CO2 retention in the carboxysome is necessary, whereas selective uptake of HCO3 (-) into the carboxysome would not appreciably enhance energetic efficiency. Altogether, integration of pH produces a model that is quantitatively consistent with cyanobacterial physiology, emphasizing that pH cannot be neglected when describing biological systems interacting with inorganic carbon pools.
Collapse
|
23
|
Rantasalo A, Czeizler E, Virtanen R, Rousu J, Lähdesmäki H, Penttilä M, Jäntti J, Mojzita D. Synthetic Transcription Amplifier System for Orthogonal Control of Gene Expression in Saccharomyces cerevisiae. PLoS One 2016; 11:e0148320. [PMID: 26901642 PMCID: PMC4762949 DOI: 10.1371/journal.pone.0148320] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/15/2016] [Indexed: 12/26/2022] Open
Abstract
This work describes the development and characterization of a modular synthetic expression system that provides a broad range of adjustable and predictable expression levels in S. cerevisiae. The system works as a fixed-gain transcription amplifier, where the input signal is transferred via a synthetic transcription factor (sTF) onto a synthetic promoter, containing a defined core promoter, generating a transcription output signal. The system activation is based on the bacterial LexA-DNA-binding domain, a set of modified, modular LexA-binding sites and a selection of transcription activation domains. We show both experimentally and computationally that the tuning of the system is achieved through the selection of three separate modules, each of which enables an adjustable output signal: 1) the transcription-activation domain of the sTF, 2) the binding-site modules in the output promoter, and 3) the core promoter modules which define the transcription initiation site in the output promoter. The system has a novel bidirectional architecture that enables generation of compact, yet versatile expression modules for multiple genes with highly diversified expression levels ranging from negligible to very strong using one synthetic transcription factor. In contrast to most existing modular gene expression regulation systems, the present system is independent from externally added compounds. Furthermore, the established system was minimally affected by the several tested growth conditions. These features suggest that it can be highly useful in large scale biotechnology applications.
Collapse
Affiliation(s)
- Anssi Rantasalo
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Elena Czeizler
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Riitta Virtanen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Juho Rousu
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Harri Lähdesmäki
- Aalto University, Department of Computer Science, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Jussi Jäntti
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Dominik Mojzita
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
- * E-mail:
| |
Collapse
|
24
|
Plášek J, Melcrová A, Gášková D. Enhanced Sensitivity of pHluorin-Based Monitoring of Intracellular pH Changes Achieved through Synchronously Scanned Fluorescence Spectra. Anal Chem 2015; 87:9600-4. [DOI: 10.1021/acs.analchem.5b02779] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jaromír Plášek
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116 Prague, Czech Republic
| | - Adéla Melcrová
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116 Prague, Czech Republic
| | - Dana Gášková
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116 Prague, Czech Republic
| |
Collapse
|
25
|
Knudsen JD, Johanson T, Eliasson Lantz A, Carlquist M. Exploring the potential of the glycerol-3-phosphate dehydrogenase 2 (GPD2) promoter for recombinant gene expression in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2015. [PMID: 28626720 PMCID: PMC5466052 DOI: 10.1016/j.btre.2015.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A control point for keeping redox homeostasis in Saccharomyces cerevisiae during fermentative growth is the dynamic regulation of transcription for the glycerol-3-phosphate dehydrogenase 2 (GPD2) gene. In this study, the possibility to steer the activity of the GPD2 promoter was investigated by placing it in strains with different ability to reoxidise NADH, and applying different environmental conditions. Flow cytometric analysis of reporter strains expressing green fluorescent protein (GFP) under the control of the GPD2 promoter was used to determine the promoter activity at the single-cell level. When placed in a gpd1Δgpd2Δ strain background, the GPD2 promoter displayed a 2-fold higher activity as compared to the strong constitutive glyceraldehyde-3-phosphate dehydrogenase (TDH3). In contrast, the GPD2 promoter was found to be inactive when cells were cultivated in continuous mode at a growth rate of 0.3 h−1 and in conditions with excess oxygen (i.e. with an aeration of 2.5 vvm, and a stirring of 800 rpm). In addition, a clear window of operation where the gpd1Δgpd2Δ strain can be grown with the same efficiency as wild type yeast was identified. In conclusion, the flow cytometry mapping revealed conditions where the GPD2 promoter was either completely inactive or hyperactive, which has implications for its implementation in future biotechnological applications such as for process control of heterologous gene expression.
Collapse
Affiliation(s)
- Jan Dines Knudsen
- Division of Applied Microbiology, Department of Chemistry, Faculty of Engineering, Lund University, Getingevägen 60, SE-22100 Lund, Sweden
| | - Ted Johanson
- Department of Systems Biology, Technical University of Denmark, Soltofts Plads, Building 223, DK-2800 Kgs. Lyngby, Denmark
| | - Anna Eliasson Lantz
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Soltofts Plads, Building 228, DK-2800 Kgs. Lyngby, Denmark
| | - Magnus Carlquist
- Division of Applied Microbiology, Department of Chemistry, Faculty of Engineering, Lund University, Getingevägen 60, SE-22100 Lund, Sweden
| |
Collapse
|
26
|
Knudsen JD, Carlquist M, Gorwa-Grauslund M. NADH-dependent biosensor in Saccharomyces cerevisiae: principle and validation at the single cell level. AMB Express 2014; 4:81. [PMID: 25401080 PMCID: PMC4230897 DOI: 10.1186/s13568-014-0081-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 10/15/2014] [Indexed: 01/28/2023] Open
Abstract
A reporter system was constructed to measure perturbations in the NADH/NAD+ co-factor balance in yeast, by using the green fluorescent protein gene under the control of the GPD2 promoter that is induced under conditions of excess of NADH. High fluorescence levels were obtained in a glycerol 3-phosphate dehydrogenase double deletion strain (gpd1Δgpd2Δ), which is deficient in the ability to regenerate NAD+ via glycerol formation. The responsiveness of the reporter system to externally induced perturbations in NADH oxidation was also evaluated in the gpd1Δgpd2Δ strain background by addition of acetoin, as well as by introduction of a set of heterologous xylose reductases (XRs) having different selectivities for NADH. Addition of acetoin during cell proliferation under oxygen-limited conditions resulted in a more than 2-fold decrease in mean fluorescence intensity as compared to the control experiment. Strains carrying XRs with different selectivities for NADH could be distinguished at the single cell level, so that the XR with the highest selectivity for NADH displayed the lowest fluorescence. In conclusion, the designed system successfully allowed for monitoring perturbations in the cellular redox metabolism caused by environmental changes, or by heterologous gene expression. The reporter system displayed high resolution in distinguishing cytosolic NADH oxidation capacity and hence has potential to be used for high-throughput screening based on the fluorescence of single cells.
Collapse
|
27
|
Single cell and in vivo analyses elucidate the effect of xylC lactonase during production of D-xylonate in Saccharomyces cerevisiae. Metab Eng 2014; 25:238-47. [DOI: 10.1016/j.ymben.2014.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/15/2014] [Accepted: 07/17/2014] [Indexed: 11/21/2022]
|
28
|
Valkonen M, Penttilä M, Benčina M. Intracellular pH responses in the industrially important fungus Trichoderma reesei. Fungal Genet Biol 2014; 70:86-93. [PMID: 25046860 DOI: 10.1016/j.fgb.2014.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/07/2014] [Accepted: 07/08/2014] [Indexed: 12/14/2022]
Abstract
Preserving an optimal intracellular pH is critical for cell fitness and productivity. The pH homeostasis of the industrially important filamentous fungus Trichoderma reesei (Hypocrea jecorina) is largely unexplored. We analyzed the impact of growth conditions on regulation of intracellular pH of the strain Rut-C30 and the strain M106 derived from the Rut-C30 that accumulates L-galactonic acid-from provided galacturonic acid-as a consequence of L-galactonate dehydratase deletion. For live-cell measurements of intracellular pH, we used the genetically encoded ratiometric pH-sensitive fluorescent protein RaVC. Glucose and lactose, used as carbon sources, had specific effects on intracellular pH of T. reesei. The growth in lactose-containing medium extensively acidified cytosol, while intracellular pH of hyphae cultured in a medium with glucose remained at a higher level. The strain M106 maintained higher intracellular pH in the presence of D-galacturonic acid than its parental strain Rut-C30. Acidic external pH caused significant acidification of cytosol. Altogether, the pH homeostasis of T. reesei Rut-C30 strain is sensitive to extracellular pH and the degree of acidification depends on carbon source.
Collapse
Affiliation(s)
- Mari Valkonen
- VTT Technical Research Centre of Finland, Espoo, Finland.
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, Espoo, Finland
| | - Mojca Benčina
- Laboratory of Biotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia; Centre of Excellence EN-FIST, 1000 Ljubljana, Slovenia.
| |
Collapse
|
29
|
Phylogeny poorly predicts the utility of a challenging horizontally transferred gene in Methylobacterium strains. J Bacteriol 2014; 196:2101-7. [PMID: 24682326 DOI: 10.1128/jb.00034-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Horizontal gene transfer plays a crucial role in microbial evolution. While much is known about the mechanisms that determine whether physical DNA can be transferred into a new host, the factors determining the utility of the transferred genes are less clear. We have explored this issue using dichloromethane consumption in Methylobacterium strains. Methylobacterium extorquens DM4 expresses a dichloromethane dehalogenase (DcmA) that has been acquired through horizontal gene transfer and allows the strain to grow on dichloromethane as the sole carbon and energy source. We transferred the dcmA gene into six Methylobacterium strains that include both close and distant evolutionary relatives. The transconjugants varied in their ability to grow on dichloromethane, but their fitness on dichloromethane did not correlate with the phylogeny of the parental strains or with any single tested physiological factor. This work highlights an important limiting factor in horizontal gene transfer, namely, the capacity of the recipient strain to accommodate the stress and metabolic disruption resulting from the acquisition of a new enzyme or pathway. Understanding these limitations may help to rationalize historical examples of horizontal transfer and aid deliberate genetic transfers in biotechnology for metabolic engineering.
Collapse
|
30
|
Benčina M. Illumination of the spatial order of intracellular pH by genetically encoded pH-sensitive sensors. SENSORS 2013; 13:16736-58. [PMID: 24316570 PMCID: PMC3892890 DOI: 10.3390/s131216736] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 11/27/2013] [Accepted: 11/27/2013] [Indexed: 12/11/2022]
Abstract
Fluorescent proteins have been extensively used for engineering genetically encoded sensors that can monitor levels of ions, enzyme activities, redox potential, and metabolites. Certain fluorescent proteins possess specific pH-dependent spectroscopic features, and thus can be used as indicators of intracellular pH. Moreover, concatenated pH-sensitive proteins with target proteins pin the pH sensors to a definite location within the cell, compartment, or tissue. This study provides an overview of the continually expanding family of pH-sensitive fluorescent proteins that have become essential tools for studies of pH homeostasis and cell physiology. We describe and discuss the design of intensity-based and ratiometric pH sensors, their spectral properties and pH-dependency, as well as their performance. Finally, we illustrate some examples of the applications of pH sensors targeted at different subcellular compartments.
Collapse
Affiliation(s)
- Mojca Benčina
- Laboratory of Biotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia.
| |
Collapse
|