1
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Hui CY, Liu MQ, Guo Y. Synthetic bacteria designed using ars operons: a promising solution for arsenic biosensing and bioremediation. World J Microbiol Biotechnol 2024; 40:192. [PMID: 38709285 DOI: 10.1007/s11274-024-04001-2] [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: 03/18/2024] [Accepted: 04/22/2024] [Indexed: 05/07/2024]
Abstract
The global concern over arsenic contamination in water due to its natural occurrence and human activities has led to the development of innovative solutions for its detection and remediation. Microbial metabolism and mobilization play crucial roles in the global cycle of arsenic. Many microbial arsenic-resistance systems, especially the ars operons, prevalent in bacterial plasmids and genomes, play vital roles in arsenic resistance and are utilized as templates for designing synthetic bacteria. This review novelty focuses on the use of these tailored bacteria, engineered with ars operons, for arsenic biosensing and bioremediation. We discuss the advantages and disadvantages of using synthetic bacteria in arsenic pollution treatment. We highlight the importance of genetic circuit design, reporter development, and chassis cell optimization to improve biosensors' performance. Bacterial arsenic resistances involving several processes, such as uptake, transformation, and methylation, engineered in customized bacteria have been summarized for arsenic bioaccumulation, detoxification, and biosorption. In this review, we present recent insights on the use of synthetic bacteria designed with ars operons for developing tailored bacteria for controlling arsenic pollution, offering a promising avenue for future research and application in environmental protection.
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Affiliation(s)
- Chang-Ye Hui
- Shenzhen Prevention and Treatment Center for Occupational Diseases, Shenzhen, China.
| | - Ming-Qi Liu
- Shenzhen Prevention and Treatment Center for Occupational Diseases, Shenzhen, China
- School of Public Health, Guangdong Medical University, Dongguan, China
| | - Yan Guo
- Shenzhen Prevention and Treatment Center for Occupational Diseases, Shenzhen, China
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2
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Frommer J, Oppenheimer R, Allott BM, Núñez-Pertíñez S, Wilks TR, Cox LR, Bath J, O'Reilly RK, Turberfield AJ. A New Architecture for DNA-Templated Synthesis in Which Abasic Sites Protect Reactants from Degradation. Angew Chem Int Ed Engl 2024; 63:e202317482. [PMID: 38346169 DOI: 10.1002/anie.202317482] [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: 11/16/2023] [Indexed: 03/01/2024]
Abstract
The synthesis of artificial sequence-defined polymers that match and extend the functionality of proteins is an important goal in materials science. One way of achieving this is to program a sequence of chemical reactions between precursor building blocks by means of attached oligonucleotide adapters. However, hydrolysis of the reactive building blocks has so far limited the length and yield of product that can be obtained using DNA-templated reactions. Here, we report an architecture for DNA-templated synthesis in which reactants are tethered at internal abasic sites on opposite strands of a DNA duplex. We show that an abasic site within a DNA duplex can protect a nearby thioester from degradation, significantly increasing the yield of a DNA-templated reaction. This protective effect has the potential to overcome the challenges associated with programmable, sequence-controlled synthesis of long non-natural polymers by extending the lifetime of the reactive building blocks.
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Affiliation(s)
- Jennifer Frommer
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Robert Oppenheimer
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
| | - Benjamin M Allott
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Samuel Núñez-Pertíñez
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Thomas R Wilks
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Liam R Cox
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Jonathan Bath
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Rachel K O'Reilly
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Andrew J Turberfield
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
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3
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Zhang Y, Boyanov MI, O'Loughlin EJ, Kemner KM, Sanford RA, Kim HS, Park SC, Kwon MJ. Reaction pathways and Sb(III) minerals formation during the reduction of Sb(V) by Rhodoferax ferrireducens strain YZ-1. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133240. [PMID: 38134691 DOI: 10.1016/j.jhazmat.2023.133240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/30/2023] [Accepted: 12/10/2023] [Indexed: 12/24/2023]
Abstract
Antimony (Sb), a non-essential metalloid, can be released into the environment through various industrial activities. Sb(III) is considered more toxic than Sb(V), but Sb(III) can be immobilized through the precipitation of insoluble Sb2S3 or Sb2O3. In the subsurface, Sb redox chemistry is largely controlled by microorganisms; however, the exact mechanisms of Sb(V) reduction to Sb(III) are still unclear. In this study, a new strain of Sb(V)-reducing bacterium, designated as strain YZ-1, that can respire Sb(V) as a terminal electron acceptor was isolated from Sb-contaminated soils. 16S-rRNA gene sequencing of YZ-1 revealed high similarity to a known Fe(III)-reducer, Rhodoferax ferrireducens. XRD and XAFS analyses revealed that bioreduction of Sb(V) to Sb(III) proceed through a transition from amorphous valentinite to crystalline senarmontite (allotropes of Sb2O3). Genomic DNA sequencing found that YZ-1 possesses arsenic (As) metabolism genes, including As(V) reductase arsC. The qPCR analysis showed that arsC was highly expressed during Sb(V)-reduction by YZ-1, and thus is proposed as the potential Sb(V) reductase in YZ-1. This study provides new insight into the pathways and products of microbial Sb(V) reduction and demonstrates the potential of a newly isolated bacterium for Sb bioremediation.
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Affiliation(s)
- Yidan Zhang
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Maxim I Boyanov
- Biosciences Division, Argonne National Laboratory, Lemont, IL 60439, USA; Bulgarian Academy of Sciences, Institute of Chemical Engineering, Sofia 1113, Bulgaria
| | | | - Kenneth M Kemner
- Biosciences Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Robert A Sanford
- Department of Earth Science & Environmental Change, University of Illinois Urbana-Champaign, Champaign, IL 61801, USA
| | - Han-Suk Kim
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Soo-Chan Park
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Man Jae Kwon
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea.
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Iqbal Z, Sadaf S. A patent-based consideration of latest platforms in the art of directed evolution: a decade long untold story. Biotechnol Genet Eng Rev 2022; 38:133-246. [PMID: 35200115 DOI: 10.1080/02648725.2021.2017638] [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] [Indexed: 02/07/2023]
Abstract
Directed (or in vitro) evolution of proteins and metabolic pathways requires tools for creating genetic diversity and identifying protein variants with new or improved functional properties. Besides simplicity, reliability, speed, versatility, universal applicability and economy of the technique, the new science of synthetic biology requires improved means for construction of smart and high-quality mutant libraries to better navigate the sequence diversity. In vitro CRISPR/Cas9-mediated mutagenic (ICM) system and machine-learning (ML)-assisted approaches to directed evolution are now in the field to achieve the goal. This review describes the gene diversification strategies, screening and selection methods, in silico (computer-aided), Cas9-mediated and ML-based approaches to mutagenesis, developed especially in the last decade, and their patent position. The objective behind is to emphasize researchers the need for noting which mutagenesis, screening or selection method is patented and then selecting a suitable restriction-free approach to sequence diversity. Techniques and evolved products subject to patent rights need commercial license if their use is for purposes other than private or experimental research.
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Affiliation(s)
- Zarina Iqbal
- IP Litigation Department, PakPat World Intellectual Property Protection Services, Lahore, Pakistan
| | - Saima Sadaf
- School of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan
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5
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Bacterial Arsenic Metabolism and Its Role in Arsenic Bioremediation. Curr Microbiol 2022; 79:131. [PMID: 35290506 DOI: 10.1007/s00284-022-02810-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 02/14/2022] [Indexed: 11/03/2022]
Abstract
Arsenic contaminations, often adversely influencing the living organisms, including plants, animals, and the microbial communities, are of grave apprehension. Many physical, chemical, and biological techniques are now being explored to minimize the adverse affects of arsenic toxicity. Bioremediation of arsenic species using arsenic loving bacteria has drawn much attention. Arsenate and arsenite are mostly uptaken by bacteria through aquaglycoporins and phosphate transporters. After entering arsenic inside bacterial cell arsenic get metabolized (e.g., reduction, oxidation, methylation, etc.) into different forms. Arsenite is sequentially methylated into monomethyl arsenic acid (MMA) and dimethyl arsenic acid (DMA), followed by a transformation of less toxic, volatile trimethyl arsenic acid (TMA). Passive remediation techniques, including adsorption, biomineralization, bioaccumulation, bioleaching, and so on are exploited by bacteria. Rhizospheric bacterial association with some specific plants enhances phytoextraction process. Arsenic-resistant rhizospheric bacteria have immense role in enhancement of crop plant growth and development, but their applications are not well studied till date. Emerging techniques like phytosuction separation (PS-S) have a promising future, but still light to be focused on these techniques. Plant-associated bioremediation processes like phytoextraction and phytosuction separation (PS-S) techniques might be modified by treating with potent bacteria for furtherance.
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Dutta K, Shityakov S, Khalifa I. New Trends in Bioremediation Technologies Toward Environment-Friendly Society: A Mini-Review. Front Bioeng Biotechnol 2021; 9:666858. [PMID: 34409018 PMCID: PMC8365754 DOI: 10.3389/fbioe.2021.666858] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/26/2021] [Indexed: 01/29/2023] Open
Abstract
Today's environmental balance has been compromised by the unreasonable and sometimes dangerous actions committed by humans to maintain their dominance over the Earth's natural resources. As a result, oceans are contaminated by the different types of plastic trash, crude oil coming from mismanagement of transporting ships spilling it in the water, and air pollution due to increasing production of greenhouse gases, such as CO2 and CH4 etc., into the atmosphere. The lands, agricultural fields, and groundwater are also contaminated by the infamous chemicals viz., polycyclic aromatic hydrocarbons, pyrethroids pesticides, bisphenol-A, and dioxanes. Therefore, bioremediation might function as a convenient alternative to restore a clean environment. However, at present, the majority of bioremediation reports are limited to the natural capabilities of microbial enzymes. Synthetic biology with uncompromised supervision of ethical standards could help to outsmart nature's engineering, such as the CETCH cycle for improved CO2 fixation. Additionally, a blend of synthetic biology with machine learning algorithms could expand the possibilities of bioengineering. This review summarized current state-of-the-art knowledge of the data-assisted enzyme redesigning to actively promote new research on important enzymes to ameliorate the environment.
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Affiliation(s)
- Kunal Dutta
- Department of Human Physiology, Vidyasagar University, Medinipur, India
| | - Sergey Shityakov
- Department of Chemoinformatics, Infochemistry Scientific Center, Saint Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University), Saint-Petersburg, Russia
| | - Ibrahim Khalifa
- Food Technology Department, Faculty of Agriculture, Benha University, Moshtohor, Egypt
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7
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Wang Y, Xue P, Cao M, Yu T, Lane ST, Zhao H. Directed Evolution: Methodologies and Applications. Chem Rev 2021; 121:12384-12444. [PMID: 34297541 DOI: 10.1021/acs.chemrev.1c00260] [Citation(s) in RCA: 175] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Directed evolution aims to expedite the natural evolution process of biological molecules and systems in a test tube through iterative rounds of gene diversifications and library screening/selection. It has become one of the most powerful and widespread tools for engineering improved or novel functions in proteins, metabolic pathways, and even whole genomes. This review describes the commonly used gene diversification strategies, screening/selection methods, and recently developed continuous evolution strategies for directed evolution. Moreover, we highlight some representative applications of directed evolution in engineering nucleic acids, proteins, pathways, genetic circuits, viruses, and whole cells. Finally, we discuss the challenges and future perspectives in directed evolution.
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Affiliation(s)
- Yajie Wang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Pu Xue
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Mingfeng Cao
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tianhao Yu
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Stephan T Lane
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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8
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Law J, Ng K, Windram OPF. The Phenotype Paradox: Lessons From Natural Transcriptome Evolution on How to Engineer Plants. FRONTIERS IN PLANT SCIENCE 2020; 11:75. [PMID: 32133018 PMCID: PMC7040092 DOI: 10.3389/fpls.2020.00075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
Plants have evolved genome complexity through iterative rounds of single gene and whole genome duplication. This has led to substantial expansion in transcription factor numbers following preferential retention and subsequent functional divergence of these regulatory genes. Here we review how this simple evolutionary network rewiring process, regulatory gene duplication followed by functional divergence, can be used to inspire synthetic biology approaches that seek to develop novel phenotypic variation for future trait based breeding programs in plants.
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Affiliation(s)
- Justin Law
- Grand Challenges in Ecosystems and the Environment, Imperial College London, Ascot, United Kingdom
| | - Kangbo Ng
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Oliver P. F. Windram
- Grand Challenges in Ecosystems and the Environment, Imperial College London, Ascot, United Kingdom
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9
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Pekrun K, De Alencastro G, Luo QJ, Liu J, Kim Y, Nygaard S, Galivo F, Zhang F, Song R, Tiffany MR, Xu J, Hebrok M, Grompe M, Kay MA. Using a barcoded AAV capsid library to select for clinically relevant gene therapy vectors. JCI Insight 2019; 4:131610. [PMID: 31723052 PMCID: PMC6948855 DOI: 10.1172/jci.insight.131610] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 10/08/2019] [Indexed: 12/20/2022] Open
Abstract
While gene transfer using recombinant adeno-associated viral (rAAV) vectors has shown success in some clinical trials, there remain many tissues that are not well transduced. Because of the recent success in reprogramming islet-derived cells into functional β cells in animal models, we constructed 2 highly complex barcoded replication competent capsid shuffled libraries and selected for high-transducing variants on primary human islets. We describe the generation of a chimeric AAV capsid (AAV-KP1) that facilitates transduction of primary human islet cells and human embryonic stem cell-derived β cells with up to 10-fold higher efficiency compared with previously studied best-in-class AAV vectors. Remarkably, this chimeric capsid also enabled transduction of both mouse and human hepatocytes at very high levels in a humanized chimeric mouse model, thus providing a versatile vector that has the potential to be used in both preclinical testing and human clinical trials for liver-based diseases and diabetes.
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Affiliation(s)
- Katja Pekrun
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Gustavo De Alencastro
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Qing-Jun Luo
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Jun Liu
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Youngjin Kim
- UCSF Diabetes Center, UCSF, San Francisco, California, USA
| | - Sean Nygaard
- Oregon Stem Cell Center, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Feorillo Galivo
- Oregon Stem Cell Center, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Feijie Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Ren Song
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Matthew R. Tiffany
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | - Jianpeng Xu
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
| | | | - Markus Grompe
- Oregon Stem Cell Center, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Mark A. Kay
- Departments of Pediatrics and Genetics, Stanford University, Stanford, California, USA
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10
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Kim JY, Yoo HW, Lee PG, Lee SG, Seo JH, Kim BG. In vivo Protein Evolution, Next Generation Protein Engineering Strategy: from Random Approach to Target-specific Approach. BIOTECHNOL BIOPROC E 2019. [DOI: 10.1007/s12257-018-0394-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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11
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Hosseini SR, Wagner A. Constraint and Contingency Pervade the Emergence of Novel Phenotypes in Complex Metabolic Systems. Biophys J 2017; 113:690-701. [PMID: 28793223 DOI: 10.1016/j.bpj.2017.06.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/25/2017] [Accepted: 06/19/2017] [Indexed: 01/23/2023] Open
Abstract
An evolutionary constraint is a bias or limitation in phenotypic variation that a biological system produces. We know examples of such constraints, but we have no systematic understanding about their extent and causes for any one biological system. We here study metabolisms, genomically encoded complex networks of enzyme-catalyzed biochemical reactions, and the constraints they experience in bringing forth novel phenotypes that allow survival on novel carbon sources. Our computational approach does not limit us to analyzing constrained variation in any one organism, but allows us to quantify constraints experienced by any metabolism. Specifically, we study metabolisms that are viable on one of 50 different carbon sources, and quantify how readily alterations of their chemical reactions create the ability to survive on a novel carbon source. We find that some metabolic phenotypes are much less likely to originate than others. For example, metabolisms viable on D-glucose are 1835 times more likely to give rise to metabolisms viable on D-fructose than on acetate. Likewise, we observe that some novel metabolic phenotypes are more contingent on parental phenotypes than others. Biochemical similarities among carbon sources can help explain the causes of these constraints. In addition, we study metabolisms that can be produced by recombination among 55 metabolisms of different bacterial strains or species, and show that their novel phenotypes are also contingent on and constrained by parental genotypes. To our knowledge, our analysis is the first to systematically quantify the incidence of constrained evolution in a broad class of biological system that is central to life and its evolution.
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Affiliation(s)
- Sayed-Rzgar Hosseini
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland; The Swiss Institute of Bioinformatics, Bioinformatics, Lausanne, Switzerland
| | - Andreas Wagner
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland; The Swiss Institute of Bioinformatics, Bioinformatics, Lausanne, Switzerland; The Santa Fe Institute, Santa Fe, New Mexico.
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12
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Hosseini SR, Martin OC, Wagner A. Phenotypic innovation through recombination in genome-scale metabolic networks. Proc Biol Sci 2016; 283:rspb.2016.1536. [PMID: 27683361 DOI: 10.1098/rspb.2016.1536] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/06/2016] [Indexed: 12/17/2022] Open
Abstract
Recombination is an important source of metabolic innovation, especially in prokaryotes, which have evolved the ability to survive on many different sources of chemical elements and energy. Metabolic systems have a well-understood genotype-phenotype relationship, which permits a quantitative and biochemically principled understanding of how recombination creates novel phenotypes. Here, we investigate the power of recombination to create genome-scale metabolic reaction networks that enable an organism to survive in new chemical environments. To this end, we use flux balance analysis, an experimentally validated computational method that can predict metabolic phenotypes from metabolic genotypes. We show that recombination is much more likely to create novel metabolic abilities than random changes in chemical reactions of a metabolic network. We also find that phenotypic innovation is more likely when recombination occurs between parents that are genetically closely related, phenotypically highly diverse, and viable on few rather than many carbon sources. Survival on a new carbon source preferentially involves reactions that are superessential, that is, essential in many metabolic networks. We validate our observations with data from 61 reconstructed prokaryotic metabolic networks. Our systematic and quantitative analysis of metabolic systems helps understand how recombination creates innovation.
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Affiliation(s)
- Sayed-Rzgar Hosseini
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Building Y27, Winterthurerstrasse 190, 8057 Zurich, Switzerland The Swiss Institute of Bioinformatics, Quartier Sorge, Batiment Genopode, 1015 Lausanne, Switzerland
| | - Olivier C Martin
- GQE-Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Andreas Wagner
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Building Y27, Winterthurerstrasse 190, 8057 Zurich, Switzerland The Swiss Institute of Bioinformatics, Quartier Sorge, Batiment Genopode, 1015 Lausanne, Switzerland The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
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Effects of Arsenite Resistance on the Growth and Functional Gene Expression of Leptospirillum ferriphilum and Acidithiobacillus thiooxidans in Pure Culture and Coculture. BIOMED RESEARCH INTERNATIONAL 2015; 2015:203197. [PMID: 26064886 PMCID: PMC4443643 DOI: 10.1155/2015/203197] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 11/18/2022]
Abstract
The response of iron-oxidizing Leptospirillum ferriphilum YSK and sulfur-oxidizing Acidithiobacillus thiooxidans A01 to arsenite under pure culture and coculture was investigated based on biochemical characterization (concentration of iron ion and pH value) and related gene expression. L. ferriphilum YSK and At. thiooxidans A01 in pure culture could adapt up to 400 mM and 800 mM As(III) after domestication, respectively, although arsenite showed a negative effect on both strains. The coculture showed a stronger sulfur and ferrous ion oxidation activity when exposed to arsenite. In coculture, the pH value showed no significant difference when under 500 mM arsenite stress, and the cell number of At. thiooxidans was higher than that in pure culture benefiting from the interaction with L. ferriphilum. The expression profile showed that the arsenic efflux system in the coculture was more active than that in pure culture, indicating that there is a synergetic interaction between At. thiooxidans A01 and L. ferriphilum YSK. In addition, a model was proposed to illustrate the interaction between arsenite and the ars operon in L. ferriphilum YSK and At. thiooxidans A01. This study will facilitate the effective application of coculture in the bioleaching process by taking advantage of strain-strain communication and coordination.
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Roy M, Giri AK, Dutta S, Mukherjee P. Integrated phytobial remediation for sustainable management of arsenic in soil and water. ENVIRONMENT INTERNATIONAL 2015; 75:180-98. [PMID: 25481297 DOI: 10.1016/j.envint.2014.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Revised: 11/10/2014] [Accepted: 11/15/2014] [Indexed: 05/08/2023]
Abstract
Arsenic (As), cited as the most hazardous substance by the U.S. Agency for Toxic Substance and Disease Registry (ATSDR, 2005), is an ubiquitous metalloid which when ingested for prolonged periods cause extensive health effects leading to ultimate untimely death. Plants and microbes can help mitigate soil and groundwater As problem since they have evolved elaborate detoxification machineries against this toxic metalloid as a result of their coexistence with this since the origin of life on earth. Utilization of the phytoremediation and bioremediation potential of the plants and microbes, respectively, is now regarded as two innovative tools that encompass biology, geology, biotechnology and allied sciences with cutting edge applications for sustainable mitigation of As epidemic. Discovery of As hyperaccumulating plants that uptake and concentrate large amounts of this toxic metalloid in their shoots or roots offered new hope to As phytoremediation, solar power based nature's own green remediation. This review focuses on how phytoremediation and bioremediation can be merged together to form an integrated phytobial remediation which could synergistically achieve the goal of large scale removal of As from soil, sediment and groundwater and overcome the drawbacks of the either processes alone. The review also points to the feasibility of the introduction of transgenic plants and microbes that bring new hope for more efficient treatment of As. The review identifies one critical research gap on the importance of remediation of As contaminated groundwater not only for drinking purpose but also for irrigation purpose and stresses that more research should be conducted on the use of constructed wetland, one of the most suitable areas of application of phytobial remediation. Finally the review has narrowed down on different phytoinvestigation and phytodisposal methods, which constitute the most essential and the most difficult part of pilot scale and field scale applications of phytoremediation programs.
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Affiliation(s)
- Madhumita Roy
- Techno India University, Salt Lake, Kolkata 700091, India
| | - Ashok K Giri
- Molecular and Human Genetics Division, CSIR-Indian Institute of Chemical Biology, 4Raja S.C. Mallick Road, Kolkata 700032, West Bengal, India
| | - Sourav Dutta
- Techno India University, Salt Lake, Kolkata 700091, India
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15
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In vivo evolution of metabolic pathways by homeologous recombination in mitotic cells. Metab Eng 2014; 23:123-35. [DOI: 10.1016/j.ymben.2014.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 01/27/2014] [Accepted: 02/12/2014] [Indexed: 12/29/2022]
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16
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Fisher MA, Boyarskiy S, Yamada MR, Kong N, Bauer S, Tullman-Ercek D. Enhancing tolerance to short-chain alcohols by engineering the Escherichia coli AcrB efflux pump to secrete the non-native substrate n-butanol. ACS Synth Biol 2014; 3:30-40. [PMID: 23991711 DOI: 10.1021/sb400065q] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The microbial conversion of sugars to fuels is a promising technology, but the byproducts of biomass pretreatment processes and the fuels themselves are often toxic at industrially relevant levels. One promising solution to these problems is to engineer efflux pumps to secrete fuels and inhibitory chemicals from the cell, increasing microbial tolerance and enabling higher fuel titer. Toward that end, we used a directed evolution strategy to generate variants of the Escherichia coli AcrB efflux pump that act on the non-native substrate n-butanol, enhancing growth rates of E. coli in the presence of this biofuel by up to 25%. Furthermore, these variants confer improved tolerance to isobutanol and straight-chain alcohols up to n-heptanol. Single amino acid changes in AcrB responsible for this phenotype were identified. We have also shown that both the chemical and genetic inactivation of pump activity eliminate the tolerance conferred by AcrB pump variants, supporting our assertion that the variants secrete the non-native substrates. This strategy can be applied to create an array of efflux pumps that modulate the intracellular concentrations of small molecules of interest to microbial fuel and chemical production.
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Affiliation(s)
- Michael A. Fisher
- Energy Biosciences
Institute, University of California Berkeley, 2151 Berkeley Way, Berkeley, California 94704, United States
| | - Sergey Boyarskiy
- Energy Biosciences
Institute, University of California Berkeley, 2151 Berkeley Way, Berkeley, California 94704, United States
- Department
of Bioengineering, University of California Berkeley, 306 Stanley
Hall MC #1762, Berkeley, California 94720, United States
| | - Masaki R. Yamada
- Department
of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
| | - Niwen Kong
- Department
of Molecular and Cell Biology, University of California Berkeley, 142 LSA #3200, Berkeley, California 94720, United States
| | - Stefan Bauer
- Energy Biosciences
Institute, University of California Berkeley, 2151 Berkeley Way, Berkeley, California 94704, United States
| | - Danielle Tullman-Ercek
- Energy Biosciences
Institute, University of California Berkeley, 2151 Berkeley Way, Berkeley, California 94704, United States
- Department
of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
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Abatemarco J, Hill A, Alper HS. Expanding the metabolic engineering toolbox with directed evolution. Biotechnol J 2013; 8:1397-410. [PMID: 23857895 DOI: 10.1002/biot.201300021] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/10/2013] [Accepted: 06/24/2013] [Indexed: 01/02/2023]
Abstract
Cellular systems can be engineered into factories that produce high-value chemicals from renewable feedstock. Such an approach requires an expanded toolbox for metabolic engineering. Recently, protein engineering and directed evolution strategies have started to play a growing and critical role within metabolic engineering. This review focuses on the various ways in which directed evolution can be applied in conjunction with metabolic engineering to improve product yields. Specifically, we discuss the application of directed evolution on both catalytic and non-catalytic traits of enzymes, on regulatory elements, and on whole genomes in a metabolic engineering context. We demonstrate how the goals of metabolic pathway engineering can be achieved in part through evolving cellular parts as opposed to traditional approaches that rely on gene overexpression and deletion. Finally, we discuss the current limitations in screening technology that hinder the full implementation of a metabolic pathway-directed evolution approach.
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Affiliation(s)
- Joseph Abatemarco
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
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18
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Eriksen DT, Hsieh PCH, Lynn P, Zhao H. Directed evolution of a cellobiose utilization pathway in Saccharomyces cerevisiae by simultaneously engineering multiple proteins. Microb Cell Fact 2013; 12:61. [PMID: 23802545 PMCID: PMC3702475 DOI: 10.1186/1475-2859-12-61] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 06/03/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The optimization of metabolic pathways is critical for efficient and economical production of biofuels and specialty chemicals. One such significant pathway is the cellobiose utilization pathway, identified as a promising route in biomass utilization. Here we describe the optimization of cellobiose consumption and ethanol productivity by simultaneously engineering both proteins of the pathway, the β-glucosidase (gh1-1) and the cellodextrin transporter (cdt-1), in an example of pathway engineering through directed evolution. RESULTS The improved pathway was assessed based on the strain specific growth rate on cellobiose, with the final mutant exhibiting a 47% increase over the wild-type pathway. Metabolite analysis of the engineered pathway identified a 49% increase in cellobiose consumption (1.78 to 2.65 g cellobiose/(L · h)) and a 64% increase in ethanol productivity (0.611 to 1.00 g ethanol/(L · h)). CONCLUSIONS By simultaneously engineering multiple proteins in the pathway, cellobiose utilization in S. cerevisiae was improved. This optimization can be generally applied to other metabolic pathways, provided a selection/screening method is available for the desired phenotype. The improved in vivo cellobiose utilization demonstrated here could help to decrease the in vitro enzyme load in biomass pretreatment, ultimately contributing to a reduction in the high cost of biofuel production.
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Abstract
Directed evolution, the laboratory process by which biological entities with desired traits are created through iterative rounds of genetic diversification and library screening or selection, has become one of the most useful and widespread tools in basic and applied biology. From its roots in classical strain engineering and adaptive evolution, modern directed evolution came of age twenty years ago with the demonstration of repeated rounds of PCR-driven random mutagenesis and activity screening to improve protein properties. Since then, numerous techniques have been developed that have enabled the evolution of virtually any protein, pathway, network or entire organism of interest. Here we recount some of the major milestones in the history of directed evolution, highlight the most promising recent developments in the field, and discuss the future challenges and opportunities that lie ahead.
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Affiliation(s)
- Ryan E. Cobb
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801
| | - Ran Chao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801
- Departments of Chemistry, Biochemistry, and Bioengineering, and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801
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20
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Eriksen DT, Lian J, Zhao H. Protein design for pathway engineering. J Struct Biol 2013; 185:234-42. [PMID: 23558037 DOI: 10.1016/j.jsb.2013.03.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 02/23/2013] [Accepted: 03/21/2013] [Indexed: 02/02/2023]
Abstract
Design and construction of biochemical pathways has increased the complexity of biosynthetically-produced compounds when compared to single enzyme biocatalysis. However, the coordination of multiple enzymes can introduce a complicated set of obstacles to overcome in order to achieve a high titer and yield of the desired compound. Metabolic engineering has made great strides in developing tools to optimize the flux through a target pathway, but the inherent characteristics of a particular enzyme within the pathway can still limit the productivity. Thus, judicious protein design is critical for metabolic and pathway engineering. This review will describe various strategies and examples of applying protein design to pathway engineering to optimize the flux through the pathway. The proteins can be engineered for altered substrate specificity/selectivity, increased catalytic activity, reduced mass transfer limitations through specific protein localization, and reduced substrate/product inhibition. Protein engineering can also be expanded to design biosensors to enable high through-put screening and to customize cell signaling networks. These strategies have successfully engineered pathways for significantly increased productivity of the desired product or in the production of novel compounds.
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Affiliation(s)
- Dawn T Eriksen
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Jiazhang Lian
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
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21
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Wagner A. The low cost of recombination in creating novel phenotypes: Recombination can create new phenotypes while disrupting well-adapted phenotypes much less than mutation. Bioessays 2011; 33:636-46. [PMID: 21633964 DOI: 10.1002/bies.201100027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recombination is often considered a disruptive force for well-adapted phenotypes, but recent evidence suggests that this cost of recombination can be small. A key benefit of recombination is that it can help create proteins and regulatory circuits with novel and useful phenotypes more efficiently than point mutation. Its effectiveness stems from the large-scale reorganization of genotypes that it causes, which can help explore far-flung regions in genotype space. Recent work on complex phenotypes in model gene regulatory circuits and proteins shows that the disruptive effects of recombination can be very mild compared to the effects of mutation. Recombination thus can have great benefits at a modest cost, but we do not understand the reasons well. A better understanding might shed light on the evolution of recombination and help improve evolutionary strategies in biochemical engineering.
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Affiliation(s)
- Andreas Wagner
- Institute of Evolutionary Biology and Environmental Sciences, University of Zurich, Zurich, Switzerland.
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22
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23
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Jez JM. Toward protein engineering for phytoremediation: possibilities and challenges. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2011; 13 Suppl 1:77-89. [PMID: 22046752 DOI: 10.1080/15226514.2011.568537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The combination of rational protein engineering and directed evolution techniques allow for the redesign of enzymes with tailored properties for use in environmental remediation. This review summarizes current molecular methods for either altering or improving protein function and highlights examples of how these methods can address bioremediation problems. Although much of the protein engineering applied to environmental clean-up employs microbial systems, there is great potential for and significant challenges to translating these approaches to plant systems for phytoremediation purposes. Protein engineering technologies combined with genomic information and metabolic engineering strategies hold promise for the design of plants and microbes to remediate organic and inorganic pollutants.
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Affiliation(s)
- Joseph M Jez
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
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24
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Tsai SL, Singh S, Chen W. Arsenic metabolism by microbes in nature and the impact on arsenic remediation. Curr Opin Biotechnol 2009; 20:659-67. [DOI: 10.1016/j.copbio.2009.09.013] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Revised: 09/17/2009] [Accepted: 09/25/2009] [Indexed: 12/20/2022]
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25
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Gong J, Zheng H, Wu Z, Chen T, Zhao X. Genome shuffling: Progress and applications for phenotype improvement. Biotechnol Adv 2009; 27:996-1005. [DOI: 10.1016/j.biotechadv.2009.05.016] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Martin OC, Wagner A. Effects of recombination on complex regulatory circuits. Genetics 2009; 183:673-84, 1SI-8SI. [PMID: 19652184 PMCID: PMC2766326 DOI: 10.1534/genetics.109.104174] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 07/27/2009] [Indexed: 11/18/2022] Open
Abstract
Mutation and recombination are the two main forces generating genetic variation. Most of this variation may be deleterious. Because recombination can reorganize entire genes and genetic circuits, it may have much greater consequences than point mutations. We here explore the effects of recombination on models of transcriptional regulation circuits that play important roles in embryonic development. We show that recombination has weaker deleterious effects on the expression phenotypes of these circuits than mutations. In addition, if a population of such circuits evolves under the influence of mutation and recombination, we find that three key properties emerge: (1) deleterious effects of mutations are reduced dramatically; (2) the diversity of genotypes in the population is greatly increased, a feature that may be important for phenotypic innovation; and (3) cis-regulatory complexes appear. These are combinations of regulatory interactions that influence the expression of one gene and that mitigate deleterious recombination effects.
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Affiliation(s)
- Olivier C Martin
- Université Paris-Sud, UMR8626, Laboratoire de Physique Théorique et Modèles Statistiques, F-91405 Orsay, France.
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27
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Picataggio S. Potential impact of synthetic biology on the development of microbial systems for the production of renewable fuels and chemicals. Curr Opin Biotechnol 2009; 20:325-9. [DOI: 10.1016/j.copbio.2009.04.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 04/27/2009] [Accepted: 04/28/2009] [Indexed: 11/29/2022]
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Abstract
Organisms often adapt to new conditions by means of beneficial mutations that become fixed in the population. Often, full adaptation requires several different mutations in the same cell, each of which may affect a different aspect of the behavior. Can one predict order in which these mutations become fixed? To address this, we experimentally studied evolution of Escherichia coli in a growth medium in which the effects of different adaptations can be easily classified as affecting growth rate or the lag-phase duration. We find that adaptations are fixed in a defined and reproducible order: first reduction of lag phase, and then an increase of the exponential growth rate. A population genetics theory explains this order, and suggests growth conditions in which the order of adaptations is reversed. We experimentally find this order reversal under the predicted conditions. This study supports a view in which the evolutionary path to adaptation in a new environment can be captured by theory and experiment.
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Affiliation(s)
- Erez Oxman
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.
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29
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Urgun-Demirtas M, Stark B, Pagilla K. Use of Genetically Engineered Microorganisms (GEMs) for the Bioremediation of Contaminants. Crit Rev Biotechnol 2008; 26:145-64. [PMID: 16923532 DOI: 10.1080/07388550600842794] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This paper presents a critical review of the literature on the application of genetically engineered microorganisms (GEMs) in bioremediation. The important aspects of using GEMs in bioremediation, such as development of novel strains with desirable properties through pathway construction and the modification of enzyme specificity and affinity, are discussed in detail. Particular attention is given to the genetic engineering of bacteria using bacterial hemoglobin (VHb) for the treatment of aromatic organic compounds under hypoxic conditions. The application of VHb technology may advance treatment of contaminated sites, where oxygen availability limits the growth of aerobic bioremediating bacteria, as well as the functioning of oxygenases required for mineralization of many organic pollutants. Despite the many advantages of GEMs, there are still concerns that their introduction into polluted sites to enhance bioremediation may have adverse environmental effects, such as gene transfer. The extent of horizontal gene transfer from GEMs in the environment, compared to that of native organisms including benefits regarding bacterial bioremediation that may occur as a result of such transfer, is discussed. Recent advances in tracking methods and containment strategies for GEMs, including several biological systems that have been developed to detect the fate of GEMs in the environment, are also summarized in this review. Critical research questions pertaining to the development and implementation of GEMs for enhanced bioremediation have been identified and posed for possible future research.
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Affiliation(s)
- Meltem Urgun-Demirtas
- Department of Chemical and Environmental Engineering, Illinois Institute of Technology, Chicago, 60616, USA
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30
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Mikheenko IP, Rousset M, Dementin S, Macaskie LE. Bioaccumulation of palladium by Desulfovibrio fructosivorans wild-type and hydrogenase-deficient strains. Appl Environ Microbiol 2008; 74:6144-6. [PMID: 18689514 PMCID: PMC2565964 DOI: 10.1128/aem.02538-07] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2007] [Accepted: 08/01/2008] [Indexed: 11/20/2022] Open
Abstract
Wild-type Desulfovibrio fructosivorans and three hydrogenase-negative mutants reduced Pd(II) to Pd(0). The location of Pd(0) nanoparticles on the cytoplasmic membrane of the mutant retaining only cytoplasmic membrane-bound hydrogenase was strong evidence for the role of hydrogenases in Pd(0) deposition. Hydrogenase activity was retained at acidic pH, shown previously to favor Pd(0) deposition.
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Affiliation(s)
- I P Mikheenko
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, England, United Kingdom
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31
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Sia SK, Gillette BM, Yang GJ. Synthetic tissue biology: tissue engineering meets synthetic biology. ACTA ACUST UNITED AC 2008; 81:354-61. [PMID: 18228264 DOI: 10.1002/bdrc.20105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We propose the term "synthetic tissue biology" to describe the use of engineered tissues to form biological systems with metazoan-like complexity. The increasing maturity of tissue engineering is beginning to render this goal attainable. As in other synthetic biology approaches, the perspective is bottom-up; here, the premise is that complex functional phenotypes (on par with those in whole metazoan organisms) can be effected by engineering biology at the tissue level. To be successful, current efforts to understand and engineer multicellular systems must continue, and new efforts to integrate different tissues into a coherent structure will need to emerge. The fruits of this research may include improved understanding of how tissue systems can be integrated, as well as useful biomedical technologies not traditionally considered in tissue engineering, such as autonomous devices, sensors, and manufacturing.
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Affiliation(s)
- Samuel K Sia
- Department of Biomedical Engineering, Columbia University, New York, New York, USA.
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32
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Chaparro-Riggers JF, Loo BL, Polizzi KM, Gibbs PR, Tang XS, Nelson MJ, Bommarius AS. Revealing biases inherent in recombination protocols. BMC Biotechnol 2007; 7:77. [PMID: 18001472 PMCID: PMC2203992 DOI: 10.1186/1472-6750-7-77] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 11/14/2007] [Indexed: 11/23/2022] Open
Abstract
Background The recombination of homologous genes is an effective protein engineering tool to evolve proteins. DNA shuffling by gene fragmentation and reassembly has dominated the literature since its first publication, but this fragmentation-based method is labor intensive. Recently, a fragmentation-free PCR based protocol has been published, termed recombination-dependent PCR, which is easy to perform. However, a detailed comparison of both methods is still missing. Results We developed different test systems to compare and reveal biases from DNA shuffling and recombination-dependent PCR (RD-PCR), a StEP-like recombination protocol. An assay based on the reactivation of β-lactamase was developed to simulate the recombination of point mutations. Both protocols performed similarly here, with slight advantages for RD-PCR. However, clear differences in the performance of the recombination protocols were observed when applied to homologous genes of varying DNA identities. Most importantly, the recombination-dependent PCR showed a less pronounced bias of the crossovers in regions with high sequence identity. We discovered that template variations, including engineered terminal truncations, have significant influence on the position of the crossovers in the recombination-dependent PCR. In comparison, DNA shuffling can produce higher crossover numbers, while the recombination-dependent PCR frequently results in one crossover. Lastly, DNA shuffling and recombination-dependent PCR both produce counter-productive variants such as parental sequences and have chimeras that are over-represented in a library, respectively. Lastly, only RD-PCR yielded chimeras in the low homology situation of GFP/mRFP (45% DNA identity level). Conclusion By comparing different recombination scenarios, this study expands on existing recombination knowledge and sheds new light on known biases, which should improve library-creation efforts. It could be shown that the recombination-dependent PCR is an easy to perform alternative to DNA shuffling.
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Affiliation(s)
- Javier F Chaparro-Riggers
- School of Chemical and Biomolecular Engineering, Parker H. Petit Institute of Bioengineering and Bioscience, 315 Ferst Drive, Atlanta, GA 30332-0363, USA.
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33
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Tang SY, Le QT, Shim JH, Yang SJ, Auh JH, Park C, Park KH. Enhancing thermostability of maltogenic amylase from Bacillus thermoalkalophilus ET2 by DNA shuffling. FEBS J 2006; 273:3335-45. [PMID: 16857016 DOI: 10.1111/j.1742-4658.2006.05337.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
DNA shuffling was used to improve the thermostability of maltogenic amylase from Bacillus thermoalkalophilus ET2. Two highly thermostable mutants, III-1 and III-2, were generated after three rounds of shuffling and recombination of mutations. Their optimal reaction temperatures were all 80 degrees C, which was 10 degrees C higher than that of the wild-type. The mutant enzyme III-1 carried seven mutations: N147D, F195L, N263S, D311G, A344V, F397S, and N508D. The half-life of III-1 was about 20 times greater than that of the wild-type at 78 degrees C. The mutant enzyme III-2 carried M375T in addition to the mutations in III-1, which was responsible for the decrease in specific activity. The half-life of III-2 was 568 min while that of the wild-type was < 1 min at 80 degrees C. The melting temperatures of III-1 and III-2, as determined by differential scanning calorimetry, increased by 6.1 degrees C and 11.4 degrees C, respectively. Hydrogen bonding, hydrophobic interaction, electrostatic interaction, proper packing, and deamidation were predicted as the mechanisms for the enhancement of thermostability in the enzymes with the mutations.
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Affiliation(s)
- Shuang-Yan Tang
- Center for Agricultural Biomaterials, and Department of Food Science and Biotechnology, School of Agricultural Biotechnology, Seoul National University, South Korea
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34
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Chatterjee R, Yuan L. Directed evolution of metabolic pathways. Trends Biotechnol 2006; 24:28-38. [PMID: 16298446 DOI: 10.1016/j.tibtech.2005.11.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 09/08/2005] [Accepted: 11/07/2005] [Indexed: 10/25/2022]
Abstract
The modification of cellular metabolism is of biotechnological and commercial significance because naturally occurring metabolic pathways are the source of diverse compounds used in fields ranging from medicine to bioremediation. Directed evolution is the experimental improvement of biocatalysts or cellular properties through iterative genetic diversification and selection procedures. The creation of novel metabolic functions without disrupting the balanced intracellular pool of metabolites is the primary challenge of pathway manipulation. The introduction of coordinated changes across multiple genetic elements, in conjunction with functional selection, presents an integrated approach for the modification of metabolism with benign physiological consequences. Directed evolution formats take advantage of the dynamic structures of genomes and genomic sub-structures and their ability to evolve in multiple directions in response to external stimuli. The elucidation, design and application of genome-restructuring mechanisms are key elements in the directed evolution of cellular metabolic pathways.
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34 Applications of Extremophiles: The Industrial Screening of Extremophiles for Valuable Biomolecules. METHODS IN MICROBIOLOGY 2006. [DOI: 10.1016/s0580-9517(08)70037-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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36
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Koga Y, Haruki M, Morikawa M, Kanaya S. Stabilities of chimeras of hyperthermophilic and mesophilic glycerol kinases constructed by DNA shuffling. J Biosci Bioeng 2005; 91:551-6. [PMID: 16233038 DOI: 10.1263/jbb.91.551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2001] [Accepted: 03/06/2001] [Indexed: 11/17/2022]
Abstract
Glycerol kinases from Thermococcus kodakaraensis KOD1 (Tk-GK) and Escherichia coli (Ec-GK) greatly differ in thermostability. The temperature (T(1/2)) at which the enzymes lose half of their activity upon incubation for 20 min is 50-55 degrees C for Ec-GK and approximately 95 degrees C for Tk-GK. To examine whether the amino acid substitutions that make Tk-GK more stable than Ec-GK are localized in a limited region, the chimeras of two parental genes encoding Tk-GK and Ec-GK were constructed by DNA shuffling. E. coli cells were transformed with a plasmid library harboring these chimeras and screened for those tht produce chimeric enzymes which are more stable than Ec-GK. Four chimeric enzymes were isolated and purified, and their biochemical properties characterized. Replacement of 83 or 93 residues in the C-terminus of Ec-GK with the corresponding ones of Tk-GK increased the T(1/2) value of Ec-GK by 25-30 degrees C. In contrast, replacement of 85 residues in the N-terminus of Ec-GK with the corresponding ones of Tk-GK reduced the T(1/2) value by 5-10 degrees C. In addition, replacement of 10 residues in the C-terminus of Tk-GK with the corresponding ones of Ec-GK reduced the T(1/2) value ot Tk-GK by approximately 15 degrees C. Measurement of the far-UV CD spectra indicates that the three-dimensional structures of the chimeric enzymes, as well as those of the parent enzymes, are similar to one another. These results suggest that the amino acid substitutions responsible for the high stability of Tk-GK are largely localized in the C-terminal region.
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Affiliation(s)
- Y Koga
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Hibbert EG, Dalby PA. Directed evolution strategies for improved enzymatic performance. Microb Cell Fact 2005; 4:29. [PMID: 16212665 PMCID: PMC1262762 DOI: 10.1186/1475-2859-4-29] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 10/07/2005] [Indexed: 11/10/2022] Open
Abstract
The engineering of enzymes with altered activity, specificity and stability, using directed evolution techniques that mimic evolution on a laboratory timescale, is now well established. However, the general acceptance of these methods as a route to new biocatalysts for organic synthesis requires further improvement of the methods for both ease-of-use and also for obtaining more significant changes in enzyme properties than is currently possible. Recent advances in library design, and methods of random mutagenesis, combined with new screening and selection tools, continue to push forward the potential of directed evolution. For example, protein engineers are now beginning to apply the vast body of knowledge and understanding of protein structure and function, to the design of focussed directed evolution libraries, with striking results compared to the previously favoured random mutagenesis and recombination of entire genes. Significant progress in computational design techniques which mimic the experimental process of library screening is also now enabling searches of much greater regions of sequence-space for those catalytic reactions that are broadly understood and, therefore, possible to model. Biocatalysis for organic synthesis frequently makes use of whole-cells, in addition to isolated enzymes, either for a single reaction or for transformations via entire metabolic pathways. As many new whole-cell biocatalysts are being developed by metabolic engineering, the potential of directed evolution to improve these initial designs is also beginning to be realised.
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Affiliation(s)
- Edward G Hibbert
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Paul A Dalby
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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38
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Abstract
Systematic approaches to directed evolution of proteins have been documented since the 1970s. The ability to recruit new protein functions arises from the considerable substrate ambiguity of many proteins. The substrate ambiguity of a protein can be interpreted as the evolutionary potential that allows a protein to acquire new specificities through mutation or to regain function via mutations that differ from the original protein sequence. All organisms have evolutionarily exploited this substrate ambiguity. When exploited in a laboratory under controlled mutagenesis and selection, it enables a protein to "evolve" in desired directions. One of the most effective strategies in directed protein evolution is to gradually accumulate mutations, either sequentially or by recombination, while applying selective pressure. This is typically achieved by the generation of libraries of mutants followed by efficient screening of these libraries for targeted functions and subsequent repetition of the process using improved mutants from the previous screening. Here we review some of the successful strategies in creating protein diversity and the more recent progress in directed protein evolution in a wide range of scientific disciplines and its impacts in chemical, pharmaceutical, and agricultural sciences.
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Affiliation(s)
- Ling Yuan
- Department of Plant and Soil Sciences, and Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY 40546, USA.
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McDaniel R, Weiss R. Advances in synthetic biology: on the path from prototypes to applications. Curr Opin Biotechnol 2005; 16:476-83. [PMID: 16019200 DOI: 10.1016/j.copbio.2005.07.002] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 06/01/2005] [Accepted: 07/01/2005] [Indexed: 11/16/2022]
Abstract
Synthetic biology combines knowledge from various disciplines including molecular biology, engineering, mathematics and physics to design and build novel proteins, genetic circuits and metabolic networks. Early efforts aimed at altering the behavior of individual elements have now evolved to focus on the construction of complex networks in single-cell and multicellular systems. Recent achievements include the development of sophisticated non-native behaviors such as bi-stability, oscillations, proteins customized for biosensing, optimized drug synthesis and programmed spatial pattern formation. The de novo construction of such systems offers valuable quantitative insight into naturally occurring information processing activities. Furthermore, as the techniques for system design, synthesis and optimization mature, we will witness a rapid growth in the capabilities of synthetic systems with a wide-range of applications.
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Affiliation(s)
- Ryan McDaniel
- Department of Molecular Biology, Princeton University, New Jersey 08544, USA
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Hibbert EG, Baganz F, Hailes HC, Ward JM, Lye GJ, Woodley JM, Dalby PA. Directed evolution of biocatalytic processes. ACTA ACUST UNITED AC 2005; 22:11-9. [PMID: 15857779 DOI: 10.1016/j.bioeng.2004.09.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 09/28/2004] [Accepted: 09/28/2004] [Indexed: 10/25/2022]
Abstract
The benefits of applying biocatalysts to organic synthesis, such as their high chemo-, regio-, and enantio-specificity and selectivity, must be seriously considered, especially where chemical routes are unavailable, complex or prohibitively expensive. In cases where a potential biocatalytic route is not yet efficient enough to compete with chemical synthesis, directed evolution, and/or process engineering could be implemented for improvements. While directed evolution has demonstrated great potential to enhance enzyme properties, there will always be some aspects of biocatalytic processes that it does not address. Even where it can be successfully applied, the resources required for its implementation must currently be weighed against the feasibility of, and resources available for developing a chemical synthesis route. Here, we review the potential of combining directed evolution with process engineering, and recent developments to improve their implementation. Favourable targets for the directed evolution of new biocatalysts are the syntheses of highly complex molecules, especially where chemistry, metabolic engineering or recombineering provide a partial solution. We also review some of the recent advances in the application of these approaches alongside the directed evolution of biocatalysts.
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Affiliation(s)
- Edward G Hibbert
- Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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Remans T, Grof CPL, Ebert PR, Schenk PM. Functional promoter analysis using an approach based on an in vitro evolution strategy. Biotechniques 2005; 38:209-10, 212, 214-6. [PMID: 15727127 DOI: 10.2144/05382st01] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In vitro evolution imitates the natural evolution of genes and has been very successfully applied to the modification of coding sequences, but it has not yet been applied to promoter sequences. We propose an alternative method for functional promoter analysis by applying an in vitro evolution scheme consisting of rounds of error-prone PCR, followed by DNA shuffling and selection of mutant promoter activities. We modified the activity in embryogenic sugarcane cells of the promoter region of the "Goldfinger" isolate of banana streak virus and obtained mutant promoter sequences that showed an average mutation rate of 2.5% after applying one round of error-prone PCR and DNA shuffling. Selection and sequencing of promoter sequences with decreased or unaltered activity allowed us to rapidly map the position of one cis-acting element that influenced promoter activity in embryogenic sugarcane cells and to discover neutral mutations that did not affect promoter function. The "selective-shotgun" approach of this promoter analysis method immediately after the promoter boundaries have been defined by 5' deletion analysis dramatically reduces the labor associated with traditional "linker-scanning" deletion analysis to reveal the position of functional promoter domains. Furthermore, this method allows the entire promoter to be investigated at once, rather than selected domains or nucleotides, increasing the prospect of identifying interacting promoter regions.
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Affiliation(s)
- Tony Remans
- The University of Queensland, St. Lucia, QLD, Australia.
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Antikainen NM, Martin SF. Altering protein specificity: techniques and applications. Bioorg Med Chem 2005; 13:2701-16. [PMID: 15781382 DOI: 10.1016/j.bmc.2005.01.059] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 01/26/2005] [Indexed: 10/25/2022]
Abstract
Protein engineering constitutes a powerful tool for generating novel proteins that serve as catalysts to induce selective chemical and biological transformations that would not otherwise be possible. Protocols that are commonly employed for altering the substrate specificity and selectivity profiles by mutating known enzymes include rational and random methods as well as techniques that entail evolution, selection and screening. Proteins identified by these techniques play important roles in a variety of industrial and medicinal applications and in the study of protein structure-function relationships. Herein we present a critical overview of methods for creating new functional proteins having altered specificity profiles and some practical case studies in which these techniques have been applied to solving problems in synthetic and medicinal chemistry and to elucidating enzyme function and biological pathways.
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Affiliation(s)
- Nina M Antikainen
- Department of Chemistry and Biochemistry, The Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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Umeno D, Tobias AV, Arnold FH. Diversifying carotenoid biosynthetic pathways by directed evolution. Microbiol Mol Biol Rev 2005; 69:51-78. [PMID: 15755953 PMCID: PMC1082795 DOI: 10.1128/mmbr.69.1.51-78.2005] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microorganisms and plants synthesize a diverse array of natural products, many of which have proven indispensable to human health and well-being. Although many thousands of these have been characterized, the space of possible natural products--those that could be made biosynthetically--remains largely unexplored. For decades, this space has largely been the domain of chemists, who have synthesized scores of natural product analogs and have found many with improved or novel functions. New natural products have also been made in recombinant organisms, via engineered biosynthetic pathways. Recently, methods inspired by natural evolution have begun to be applied to the search for new natural products. These methods force pathways to evolve in convenient laboratory organisms, where the products of new pathways can be identified and characterized in high-throughput screening programs. Carotenoid biosynthetic pathways have served as a convenient experimental system with which to demonstrate these ideas. Researchers have mixed, matched, and mutated carotenoid biosynthetic enzymes and screened libraries of these "evolved" pathways for the emergence of new carotenoid products. This has led to dozens of new pathway products not previously known to be made by the assembled enzymes. These new products include whole families of carotenoids built from backbones not found in nature. This review details the strategies and specific methods that have been employed to generate new carotenoid biosynthetic pathways in the laboratory. The potential application of laboratory evolution to other biosynthetic pathways is also discussed.
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Affiliation(s)
- Daisuke Umeno
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
| | - Alexander V. Tobias
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
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Chapter 10 Non-affinity sensing technology: the exploitation of biocatalytic events for environmental analysis. BIOSENSORS AND MODERN BIOSPECIFIC ANALYTICAL TECHNIQUES 2005. [DOI: 10.1016/s0166-526x(05)44010-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Chen W, Mulchandani A, Deshusses MA. Environmental biotechnology: Challenges and opportunities for chemical engineers. AIChE J 2005. [DOI: 10.1002/aic.10487] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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46
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Schmidt AC, Mattusch J, Reisser W, Wennrich R. Evaluation of the influence of arsenic species on the nitrogen metabolism of a model angiosperm: nasturtium,Tropaeolum majus. Appl Organomet Chem 2005. [DOI: 10.1002/aoc.869] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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47
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48
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Abstract
A drawback to generating chimeric proteins by chimeragenesis, especially when the "parent" proteins share low sequence identity, is that unfolded proteins frequently result. In this issue of Chemistry & Biology, Arnold and coworkers report their use of the SCHEMA algorithm to effectively predict ideal hybrids of cytochromes p450.
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Affiliation(s)
- Rita Bernhardt
- Department of Biochemistry, PO Box 15 11 50, Saarland University, D-66041 Saarbrücken, Germany
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49
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Abstract
Enzyme catalysis in low water containing organic solvents is finding an increasing number of applications in diverse areas. This review focuses on some aspects which have not been reviewed elsewhere. Different strategies for obtaining higher activity and stability in such media are described. In this context, the damaging role of lyophilization and the means of overcoming such effects are discussed. Ultrasonication and microwave assistance are two emerging approaches for enhancing reaction rates in low water media. Control of water activity and medium engineering are two crucial approaches in optimization of catalytic behaviour in nonaqueous enzymology. Organometallics and synthesis/modification of polymers are two areas where nonaqueous enzymology can play a greater role in the coming years. The greater understanding of enzyme behaviour in nonaqueous media is expected to lead to larger and even more diverse kinds of applications.
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Affiliation(s)
- Munishwar N Gupta
- Chemistry Department, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, India.
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50
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Affiliation(s)
- Osamu Kagami
- Marine Biotechnology Institute, Kamaishi Wate, Japan
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