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Li S, He H, Zhang Y, Ning X, Ding Z, Zhang L, Li Y, Shi G. Identification of a Novel Lactose-Specific PTS Operon in Bacillus licheniformis and Development of Derivative Artificial Operon Modules. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37927088 DOI: 10.1021/acs.jafc.3c05307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Bacillus licheniformis plays a crucial role as a microbial host in the food industry and shows promising potential as a probiotic for human intestinal regulation. It exhibits a remarkable ability to utilize lactose as its sole carbon source. Despite its significance, the lactose-related metabolic pathway in this strain remains unclear. In this study, we identified a novel lactose-specific operon (lacDCAB) in B. licheniformis, consisting of the lacD gene that encodes a unique 6-phospho-β-galactosidase belonging to the GH4 family, and the lacCAB genes encoding a lactose-specific PTS1 system. Notably, we constructed and assessed an array library of transport and catabolic modules specifically for lactose utilization. Among these modules, PDS-lacD-P2-pts1 demonstrated the highest specific lactose consumption rate of 0.64 g/(L·h·OD), which was 8 times higher than that of the control strain. Furthermore, we developed a dual carbon source transport model based on the PDS-lacD-P2-pts1 assembly module, which highlighted efficient coutilization of glucose/sucrose, lactose/sucrose, lactose/galactose, and lactose/2,3-butanediol. This study provides insight into the lactose-specific metabolic pathway of B. licheniformis and presents a promising strategy for enhancing lactose utilization efficiency and mixed carbon source coutilization.
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Affiliation(s)
- Siyu Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Hehe He
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Yupeng Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Xuewei Ning
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Zhongyang Ding
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Liang Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Youran Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Guiyang Shi
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi 214122, People's Republic of China
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Cecílio P, Oristian J, Meneses C, Serafim TD, Valenzuela JG, Cordeiro da Silva A, Oliveira F. Engineering a vector-based pan-Leishmania vaccine for humans: proof of principle. Sci Rep 2020; 10:18653. [PMID: 33122717 PMCID: PMC7596519 DOI: 10.1038/s41598-020-75410-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 09/23/2020] [Indexed: 12/14/2022] Open
Abstract
Leishmaniasis is a spectrum of diseases transmitted by sand fly vectors that deposit Leishmania spp. parasites in the host skin during blood feeding. Currently, available treatment options are limited, associated with high toxicity and emerging resistance. Even though a vaccine for human leishmaniasis is considered an achievable goal, to date we still do not have one available, a consequence (amongst other factors) of a lack of pre-clinical to clinical translatability. Pre-exposure to uninfected sand fly bites or immunization with defined sand fly salivary proteins was shown to negatively impact infection. Still, cross-protection reports are rare and dependent on the phylogenetic proximity of the sand fly species, meaning that the applicability of a sand fly saliva-based vaccine will be limited to a defined geography, one parasite species and one form of leishmaniasis. As a proof of principle of a future vector saliva-based pan-Leishmania vaccine, we engineered through a reverse vaccinology approach that maximizes translation to humans, a fusion protein consisting of immunogenic portions of PdSP15 and LJL143, sand fly salivary proteins demonstrated as potential vaccine candidates against cutaneous and visceral leishmaniasis, respectively. The in silico analysis was validated ex vivo, through T cell proliferation experiments, proving that the fusion protein (administered as a DNA vaccine) maintained the immunogenicity of both PdSP15 and LJL143. Additionally, while no significant effect was detected in the context of L. major transmission by P. duboscqi, this DNA vaccine was defined as partially protective, in the context of L. major transmission by L. longipalpis sand flies. Importantly, a high IFNγ response alone was not enough to confer protection, that mainly correlated with low T cell mediated Leishmania-specific IL-4 and IL-10 responses, and consequently with high pro/anti-inflammatory cytokine ratios. Overall our immunogenicity data suggests that to design a potentially safe vector-based pan-Leishmania vaccine, without geographic restrictions and against all forms of leishmaniasis is an achievable goal. This is why we propose our approach as a proof-of principle, perhaps not only applicable to the anti-Leishmania vector-based vaccines’ field, but also to other branches of knowledge that require the design of multi-epitope T cell vaccines with a higher potential for translation.
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Affiliation(s)
- Pedro Cecílio
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Departamento de Ciências Biológicas, Faculdade de Farmácia da Universidade do Porto (FFUP), Porto, Portugal.,Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - James Oristian
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Claudio Meneses
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Tiago D Serafim
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Jesus G Valenzuela
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA
| | - Anabela Cordeiro da Silva
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal. .,Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal. .,Departamento de Ciências Biológicas, Faculdade de Farmácia da Universidade do Porto (FFUP), Porto, Portugal.
| | - Fabiano Oliveira
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD, 20852, USA.
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Willson BJ, Chapman LNM, Thomas GH. Evolutionary dynamics of membrane transporters and channels: enhancing function through fusion. Curr Opin Genet Dev 2019; 58-59:76-86. [DOI: 10.1016/j.gde.2019.07.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 02/05/2023]
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Anand R, Agrawal M, Mattaparthi VS, Swaminathan R, Santra SB. Consequences of Heterogeneous Crowding on an Enzymatic Reaction: A Residence Time Monte Carlo Approach. ACS OMEGA 2019; 4:727-736. [PMID: 31459357 PMCID: PMC6649177 DOI: 10.1021/acsomega.8b02863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/26/2018] [Indexed: 05/06/2023]
Abstract
Translational diffusion of a free substrate in crowded metabolically active spaces such as cell cytoplasm or mitochondrial matrix is punctuated by collisions and nonspecific interactions with soluble/immobile macromolecules/macrostructures in a variety of shapes/sizes. It is not understood how such disruptions alter enzyme reaction kinetics in such spaces. A novel Monte Carlo (MC) technique, "residence time MC", has been developed to study the kinetics of a simple enzyme-substrate reaction in a crowded milieu using a single immobile enzyme in the midst of diffusing substrates and products. The reaction time lost while the substrate nonspecifically interacts or is transiently trapped with ambient macromolecules is quantified by introducing the residence time "tau". Tau scales with the size of crowding macromolecules but makes the knowledge of their shape redundant. The residence time thus presents a convenient parameter to realistically mimic the sticky surroundings encountered by a diffusing substrate in heterogeneously crowded physiological spaces. Results reveal that for identical substrate concentration and excluded volume, increase in tau significantly diminished enzymatic product yield and reaction rate, slowed down substrate/product diffusion, and prolonged their relaxation times. A smooth transition from the anomalous subdiffusive motion to normal diffusion at long time limits was observed irrespective of the value of tau. The predictions from the model are shown to be in qualitative agreement with in vitro experimental data revealing the rate of alkaline phosphatase-catalyzed hydrolysis of p-nitrophenyl phosphate in the midst of 40/500/2000 kDa dextrans. Our findings from the residence time MC model also attempt to rationalize previously unexplained experimental observations in crowded enzyme kinetics literature. Furthermore, major insights to emerge from this study are the reasons why free diffusion of the substrate in crowded physiological spaces is detrimental to enzyme function. It is argued that organized enzyme clusters such as "metabolon" may perhaps exist to regulate the substrate translocation in such sticky physiological spaces to maintain optimal enzyme function. In summary, this work provides key insights explaining why absence of substrate channeling can dramatically slow down enzyme reaction rate in crowded metabolically active spaces.
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Affiliation(s)
- Rajat Anand
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Manish Agrawal
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Venkata Satish
Kumar Mattaparthi
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Rajaram Swaminathan
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
- E-mail:
| | - Sitangshu Bikas Santra
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
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Roberts CC, Chang CEA. Modeling of enhanced catalysis in multienzyme nanostructures: effect of molecular scaffolds, spatial organization, and concentration. J Chem Theory Comput 2016; 11:286-92. [PMID: 26574226 DOI: 10.1021/ct5007482] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Colocalized multistep enzymatic reaction pathways within biological catabolic and metabolic processes occur with high yield and specificity. Spatial organization on membranes or surfaces may be associated with increased efficiency of intermediate substrate transfer. Using a new Brownian dynamics package, GeomBD, we explored the geometric features of a surface-anchored enzyme system by parallel coarse-grained Brownian dynamics simulations of substrate diffusion over microsecond (μs) to millisecond (ms) time scales. We focused on a recently developed glucose oxidase (GOx), horseradish peroxidase (HRP), and DNA origami-scaffold enzyme system, where the H2O2 substrate of HRP is produced by GOx. The results revealed and explained a significant advantage in catalytic enhancement by optimizing interenzyme distance and orientation in the presence of the scaffold model. The planar scaffold colocalized the enzymes and provided a diffusive barrier that enhanced substrate transfer probability, becoming more relevant with increasing interenzyme distance. The results highlight the importance of protein geometry in the proper assessment of distance and orientation dependence on the probability of substrate transfer. They shed light on strategies for engineering multienzyme complexes and further investigation of enhanced catalytic efficiency for substrate diffusion between membrane-anchoring proteins.
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Affiliation(s)
- Christopher C Roberts
- Department of Chemistry, University of California , Riverside, California 92521, United States
| | - Chia-en A Chang
- Department of Chemistry, University of California , Riverside, California 92521, United States
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Somavanshi R, Ghosh B, Sourjik V. Sugar Influx Sensing by the Phosphotransferase System of Escherichia coli. PLoS Biol 2016; 14:e2000074. [PMID: 27557415 PMCID: PMC4996493 DOI: 10.1371/journal.pbio.2000074] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/20/2016] [Indexed: 12/05/2022] Open
Abstract
The phosphotransferase system (PTS) plays a pivotal role in the uptake of multiple sugars in Escherichia coli and many other bacteria. In the cell, individual sugar-specific PTS branches are interconnected through a series of phosphotransfer reactions, thus creating a global network that not only phosphorylates incoming sugars but also regulates a number of cellular processes. Despite the apparent importance of the PTS network in bacterial physiology, the holistic function of the network in the cell remains unclear. Here we used Förster resonance energy transfer (FRET) to investigate the PTS network in E. coli, including the dynamics of protein interactions and the processing of different stimuli and their transmission to the chemotaxis pathway. Our results demonstrate that despite the seeming complexity of the cellular PTS network, its core part operates in a strikingly simple way, sensing the overall influx of PTS sugars irrespective of the sugar identity and distributing this information equally through all studied branches of the network. Moreover, it also integrates several other specific metabolic inputs. The integrated output of the PTS network is then transmitted linearly to the chemotaxis pathway, in stark contrast to the amplification of conventional chemotactic stimuli. Finally, we observe that default uptake through the uninduced PTS network correlates well with the quality of the carbon source, apparently representing an optimal regulatory strategy. The bacterial phosphotransferase system (PTS) mediates uptake of multiple sugars from the environment and also controls cell physiology and swimming behavior in sugar gradients. In Escherichia coli and other bacteria, the PTS consists of a number of sugar-specific branches, interconnected via shared components through a series of phosphotransfer reactions. Whereas most previous studies have focused on understanding individual PTS branches, the holistic function of the entire PTS network in the cell remained elusive. In this study we address this question by investigating the dynamics of multiple protein interactions within the cellular PTS network upon stimulation with sugars and other metabolites. We demonstrate that despite its seeming complexity, the core part of the PTS network operates in a strikingly simple way, sensing the overall influx of PTS sugars and key metabolites into the cell and utilizing this information to control bacterial behavior. We further show that the default influx of the carbon source correlates with its quality, and we use computer simulations to demonstrate that this correlation apparently represents an optimal regulatory strategy.
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Affiliation(s)
- Rahul Somavanshi
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Bhaswar Ghosh
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
- * E-mail:
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Roberts CC, Chang CEA. Analysis of Ligand-Receptor Association and Intermediate Transfer Rates in Multienzyme Nanostructures with All-Atom Brownian Dynamics Simulations. J Phys Chem B 2016; 120:8518-31. [PMID: 27248669 DOI: 10.1021/acs.jpcb.6b02236] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present the second-generation GeomBD Brownian dynamics software for determining interenzyme intermediate transfer rates and substrate association rates in biomolecular complexes. Substrate and intermediate association rates for a series of enzymes or biomolecules can be compared between the freely diffusing disorganized configuration and various colocalized or complexed arrangements for kinetic investigation of enhanced intermediate transfer. In addition, enzyme engineering techniques, such as synthetic protein conjugation, can be computationally modeled and analyzed to better understand changes in substrate association relative to native enzymes. Tools are provided to determine nonspecific ligand-receptor association residence times, and to visualize common sites of nonspecific association of substrates on receptor surfaces. To demonstrate features of the software, interenzyme intermediate substrate transfer rate constants are calculated and compared for all-atom models of DNA origami scaffold-bound bienzyme systems of glucose oxidase and horseradish peroxidase. Also, a DNA conjugated horseradish peroxidase enzyme was analyzed for its propensity to increase substrate association rates and substrate local residence times relative to the unmodified enzyme. We also demonstrate the rapid determination and visualization of common sites of nonspecific ligand-receptor association by using HIV-1 protease and an inhibitor, XK263. GeomBD2 accelerates simulations by precomputing van der Waals potential energy grids and electrostatic potential grid maps, and has a flexible and extensible support for all-atom and coarse-grained force fields. Simulation software is written in C++ and utilizes modern parallelization techniques for potential grid preparation and Brownian dynamics simulation processes. Analysis scripts, written in the Python scripting language, are provided for quantitative simulation analysis. GeomBD2 is applicable to the fields of biophysics, bioengineering, and enzymology in both predictive and explanatory roles.
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Affiliation(s)
- Christopher C Roberts
- Department of Chemistry, University of California , Riverside, California 92521, United States
| | - Chia-En A Chang
- Department of Chemistry, University of California , Riverside, California 92521, United States
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Sührer I, Haslbeck M, Castiglione K. Asymmetric synthesis of a fluoxetine precursor with an artificial fusion protein of a ketoreductase and a formate dehydrogenase. Process Biochem 2014. [DOI: 10.1016/j.procbio.2014.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Compartmentalization and metabolic channeling for multienzymatic biosynthesis: practical strategies and modeling approaches. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2013; 137:41-65. [PMID: 23934361 DOI: 10.1007/10_2013_221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
: The construction of efficient enzyme complexes for multienzymatic biosynthesis is of increasing interest in order to achieve maximum yield and to minimize the interference due to shortcomings that are typical for straightforward one-pot multienzyme catalysis. These include product or intermediate feedback inhibition, degeneration, and diffusive losses of reaction intermediates, consumption of co-factors, and others. The main mechanisms in nature to tackle these effects in transient or stable protein associations are the formation of metabolic channeling and microcompartments, processes that are desirable also for multienzymatic biosynthesis in vitro. This chapter provides an overview over two main aspects. First, numerous recent strategies for establishing compartmentalized multienzyme associations and constructed synthetic enzyme complexes are reviewed. Second, the computational methods at hand to investigate and optimize such associations systematically, especially with focus on large multienzyme complexes and metabolic channeling, are discussed. Perspectives on future studies of multienzymatic biosynthesis concerning compartmentalization and metabolic channeling are presented.
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A single mutation in enzyme I of the sugar phosphotransferase system confers penicillin tolerance to Streptococcus gordonii. Antimicrob Agents Chemother 2009; 54:259-66. [PMID: 19858257 DOI: 10.1128/aac.00699-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tolerance is a poorly understood phenomenon that allows bacteria exposed to a bactericidal antibiotic to stop their growth and withstand drug-induced killing. This survival ability has been implicated in antibiotic treatment failures. Here, we describe a single nucleotide mutation (tol1) in a tolerant Streptococcus gordonii strain (Tol1) that is sufficient to provide tolerance in vitro and in vivo. It induces a proline-to-arginine substitution (P483R) in the homodimerization interface of enzyme I of the sugar phosphotransferase system, resulting in diminished sugar uptake. In vitro, the susceptible wild-type (WT) and Tol1 cultures lost 4.5 and 0.6 log(10) CFU/ml, respectively, after 24 h of penicillin exposure. The introduction of tol1 into the WT (WT P483R) conferred tolerance (a loss of 0.7 log(10) CFU/ml/24 h), whereas restitution of the parent sequence in Tol1 (Tol1 R483P) restored antibiotic susceptibility. Moreover, penicillin treatment of rats in an experimental model of endocarditis showed a complete inversion in the outcome, with a failure of therapy in rats infected with WT P483R and the complete disappearance of bacteria in animals infected with Tol1 R483P.
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Conrado RJ, Varner JD, DeLisa MP. Engineering the spatial organization of metabolic enzymes: mimicking nature's synergy. Curr Opin Biotechnol 2008; 19:492-9. [DOI: 10.1016/j.copbio.2008.07.006] [Citation(s) in RCA: 238] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 07/24/2008] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
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Kourtz L, Dillon K, Daughtry S, Madison LL, Peoples O, Snell KD. A novel thiolase-reductase gene fusion promotes the production of polyhydroxybutyrate in Arabidopsis. PLANT BIOTECHNOLOGY JOURNAL 2005; 3:435-47. [PMID: 17173631 DOI: 10.1111/j.1467-7652.2005.00136.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The production of polyhydroxybutyrate (PHB) involves a multigene pathway consisting of thiolase, reductase and synthase genes. In order to simplify this pathway for plant-based expression, a library of thiolase and reductase gene fusions was generated by randomly ligating a short core linker DNA sequence to create in-frame fusions between the thiolase and reductase genes. The resulting fusion constructs were screened for PHB formation in Escherichia coli. This screen identified a polymer-producing candidate in which the thiolase and reductase genes were fused via a 26-amino-acid linker. This gene fusion, designated phaA-phaB, represents an active gene fusion of two homotetrameric enzymes. Expression of phaA-phaB in E. coli and Arabidopsis yielded a fusion protein observed to be the expected size by Western blotting techniques. The fusion protein exhibited thiolase and reductase enzyme activities in crude extracts of recombinant E. coli that were three-fold and nine-fold less than those of the individually expressed thiolase and reductase enzymes, respectively. When targeted to the plastid, and coexpressed with a plastid-targeted polyhydroxyalkanoate (PHA) synthase, the fusion protein enabled PHB formation in Arabidopsis, yielding roughly half the PHB formed in plants expressing individual thiolase, reductase and synthase enzymes. This work represents a first step towards simplifying the expression of the PHB biosynthetic pathway in plants.
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Siebold C, Arnold I, Garcia-Alles LF, Baumann U, Erni B. Crystal structure of the Citrobacter freundii dihydroxyacetone kinase reveals an eight-stranded alpha-helical barrel ATP-binding domain. J Biol Chem 2003; 278:48236-44. [PMID: 12966101 DOI: 10.1074/jbc.m305942200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dihydroxyacetone kinases are a sequence-conserved family of enzymes, which utilize two different phosphoryldonors, ATP in animals, plants and some bacteria, and a multiphosphoprotein of the phosphoenolpyruvate carbohydrate phosphotransferase system in bacteria. Here we report the 2.5-A crystal structure of the homodimeric Citrobacter freundii dihydroxyacetone kinase complex with an ATP analogue and dihydroxyacetone. The N-terminal domain consists of two alpha/beta-folds with a molecule of dihydroxyacetone covalently bound in hemiaminal linkage to the N epsilon 2 of His-220. The C-terminal domain consists of a regular eight-helix alpha-barrel. The eight helices form a deep pocket, which includes a tightly bound phospholipid. Only the lipid headgroup protrudes from the surface. The nucleotide is bound on the top of the barrel across from the entrance to the lipid pocket. The phosphate groups are coordinated by two Mg2+ ions to gamma-carboxyl groups of aspartyl residues. The ATP binding site does not contain positively charged or aromatic groups. Paralogues of dihydroxyacetone kinase also occur in association with transcription regulators and proteins of unknown function pointing to biological roles beyond triose metabolism.
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Affiliation(s)
- Christian Siebold
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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André A, Maccheroni W, Doignon F, Garnier M, Renaudin J. Glucose and trehalose PTS permeases of Spiroplasma citri probably share a single IIA domain, enabling the spiroplasma to adapt quickly to carbohydrate changes in its environment. MICROBIOLOGY (READING, ENGLAND) 2003; 149:2687-2696. [PMID: 12949193 DOI: 10.1099/mic.0.26336-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Spiroplasma citri is a plant-pathogenic mollicute phylogenetically related to Gram-positive bacteria. Spiroplasma cells are restricted to the phloem sieve tubes and are transmitted from plant to plant by the leafhopper vector Circulifer haematoceps. In the plant sieve tubes, S. citri grows on glucose and fructose, whereas in the leafhopper haemolymph the spiroplasma must grow on trehalose, the major sugar in insects. Previous studies in this laboratory have shown that fructose utilization was a key factor of spiroplasmal pathogenicity. To further study the implication of sugar metabolism in the interactions of S. citri with its plant host and its leafhopper vector, genes encoding permease enzymes II (EII(Glc) and EII(Tre)) of the S. citri phosphoenolpyruvate : glucose and phosphoenolpyruvate : trehalose phosphotransferase systems (PTS) were characterized. Mapping studies revealed that the EII(Glc) complex was split into two distinct polypeptides, IIA(Glc) and IICB(Glc), encoded by two separate genes, crr and ptsG, respectively. As expected, S. citri polypeptides IIA(Glc) and IICB(Glc) were more phylogenetically related to their counterparts from Gram-positive than to those from Gram-negative bacteria. The trehalose operon consisted of three genes treR, treP and treA, encoding a transcriptional regulator, the PTS permease (EII(Tre)) and the amylase, respectively. However, in contrast to the fructose-PTS permease, which is encoded as a single polypeptide (IIABC(Fru)) containing the three domains A, B and C, the trehalose-PTS permease (IIBC(Tre)) lacks its own IIA domain. No trehalose-specific IIA could be identified in the spiroplasmal genome, suggesting that the IIBC(Tre) permease probably functions with the IIA(Glc) domain. In agreement with this statement, yeast two-hybrid system experiments revealed that the IIA(Glc) domain interacted not only with IIB(Glc) but also with the IIB(Tre) domain. The results are discussed with respect to the ability of the spiroplasma to adapt from the phloem sap of the host plant to the haemolymph and salivary gland cells of the insect vector.
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Affiliation(s)
- Aurélie André
- UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France
| | - Walter Maccheroni
- UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France
| | - François Doignon
- Laboratoire de Biologie Moléculaire et de Séquençage, UMR Université Victor Segalen Bordeaux 2-CNRS 5095, IBGC, 146 rue Léo Saignat, BP 64, 33076 Bordeaux Cedex, France
| | - Monique Garnier
- UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France
| | - Joël Renaudin
- UMR Génomique Développement et Pouvoir Pathogène, IBVM, Centre INRA de Bordeaux, 71 avenue Edouard Bourlaux, BP 81, 33883 Villenave d'Ornon Cedex, France
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15
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Siebold C, Flükiger K, Beutler R, Erni B. Carbohydrate transporters of the bacterial phosphoenolpyruvate: sugar phosphotransferase system (PTS). FEBS Lett 2001; 504:104-11. [PMID: 11532441 DOI: 10.1016/s0014-5793(01)02705-3] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The glucose transporter of Escherichia coli couples translocation with phosphorylation of glucose. The IICB(Glc) subunit spans the membrane eight times. Split, circularly permuted and cyclized forms of IICB(Glc) are described. The split variant was 30 times more active when the two proteins were encoded by a dicistronic mRNA than by two genes. The stability and activity of circularly permuted forms was improved when they were expressed as fusion proteins with alkaline phosphatase. Cyclized IICB(Glc) and IIA(Glc) were produced in vivo by RecA intein-mediated trans-splicing. Purified, cyclized IIA(Glc) and IICB(Glc) had 100% and 30% of wild-type glucose phosphotransferase activity, respectively. Cyclized IIA(Glc) displayed increased stability against temperature and GuHCl-induced unfolding.
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Affiliation(s)
- C Siebold
- Departement für Chemie und Biochemie, Universität Bern, CH-3012, Bern, Switzerland
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16
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Gutknecht R, Beutler R, Garcia-Alles LF, Baumann U, Erni B. The dihydroxyacetone kinase of Escherichia coli utilizes a phosphoprotein instead of ATP as phosphoryl donor. EMBO J 2001; 20:2480-6. [PMID: 11350937 PMCID: PMC125457 DOI: 10.1093/emboj/20.10.2480] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The dihydroxyacetone kinase (DhaK) of Escherichia coli consists of three soluble protein subunits. DhaK (YcgT; 39.5 kDa) and DhaL (YcgS; 22.6 kDa) are similar to the N- and C-terminal halves of the ATP-dependent DhaK ubiquitous in bacteria, animals and plants. The homodimeric DhaM (YcgC; 51.6 kDa) consists of three domains. The N-terminal dimerization domain has the same fold as the IIA domain (PDB code 1PDO) of the mannose transporter of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS). The middle domain is similar to HPr and the C-terminus is similar to the N-terminal domain of enzyme I (EI) of the PTS. DhaM is phosphorylated three times by phosphoenolpyruvate in an EI- and HPr-dependent reaction. DhaK and DhaL are not phosphorylated. The IIA domain of DhaM, instead of ATP, is the phosphoryl donor to dihydroxyacetone (Dha). Unlike the carbohydrate-specific transporters of the PTS, DhaK, DhaL and DhaM have no transport activity.
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Affiliation(s)
| | | | | | | | - Bernhard Erni
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
Corresponding author e-mail:
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17
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Rognan D, Mukhija S, Folkers G, Zerbe O. NMR-restrained docking of a peptidic inhibitor to the N-terminal domain of the phosphoenolpyruvate:sugar phosphotransferase enzyme I. J Comput Aided Mol Des 2001; 15:103-15. [PMID: 11272698 DOI: 10.1023/a:1008145813315] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Starting from the NMR structure of the binary complex between the N-terminal domain of the unphosphorylated enzyme I (EIN) of the phosphoenolpyruvate:sugar phosphotransferase (PTS) and the histidine-containing phosphocarrier protein (HPr), a molecular model of the phosphorylated transition state of the related complex was established using constrained simulated annealing. The coordinates of the phosphorylated EIN enzyme were then used in a second step for flexible docking of a decapeptide inhibitor of EIN whose enzyme-bound conformation itself was determined by NMR using transferred nuclear Overhauser effects. Two phosphorylation models of the peptide inhibitor were investigated and shown to be both functional. Interestingly, one model is very similar to that of the complex between EIN and its natural substrate HPr. The present study demonstrates that NMR-guided flexible docking constitutes an interesting tool for docking highly flexible peptide ligands and facilitates the upcoming protein-based design of nonpeptide EIN inhibitors for discovering new antibiotics.
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Affiliation(s)
- D Rognan
- Department of Applied Biosciences, Swiss Federal Institute of Technology, Zürich.
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18
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Abdulaev NG, Ngo T, Chen R, Lu Z, Ridge KD. Functionally discrete mimics of light-activated rhodopsin identified through expression of soluble cytoplasmic domains. J Biol Chem 2000; 275:39354-63. [PMID: 10988291 DOI: 10.1074/jbc.m005642200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Numerous studies on the seven-helix receptor rhodopsin have implicated the cytoplasmic loops and carboxyl-terminal region in the binding and activation of proteins involved in visual transduction and desensitization. In our continuing studies on rhodopsin folding, assembly, and structure, we have attempted to reconstruct the interacting surface(s) for these proteins by inserting fragments corresponding to the cytoplasmic loops and/or the carboxyl-terminal tail of bovine opsin either singly, or in combination, onto a surface loop in thioredoxin. The purpose of the thioredoxin fusion is to provide a soluble scaffold for the cytoplasmic fragments thereby allowing them sufficient conformational freedom to fold to a structure that mimics the protein-binding sites on light-activated rhodopsin. All of the fusion proteins are expressed to relatively high levels in Escherichia coli and can be purified using a two- or three-step chromatography procedure. Biochemical studies show that some of the fusion proteins effectively mimic the activated conformation(s) of rhodopsin in stimulating G-protein or competing with the light-activated rhodopsin/G-protein interaction, in supporting phosphorylation of the carboxyl-terminal opsin fragment by rhodopsin kinase, and/or phosphopeptide-stimulated arrestin binding. These results suggest that specific segments of the cytoplasmic surface of rhodopsin can adopt functionally discrete conformations in the absence of the connecting transmembrane helices and retinal chromophore.
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Affiliation(s)
- N G Abdulaev
- Center for Advanced Research in Biotechnology, National Institute of Standards and Technology and the University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA
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19
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Henstra SA, Duurkens RH, Robillard GT. Multiple phosphorylation events regulate the activity of the mannitol transcriptional regulator MtlR of the Bacillus stearothermophilus phosphoenolpyruvate-dependent mannitol phosphotransferase system. J Biol Chem 2000; 275:7037-44. [PMID: 10702268 DOI: 10.1074/jbc.275.10.7037] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
D-mannitol is taken up by Bacillus stearothermophilus and phosphorylated via a phosphoenolpyruvate-dependent phosphotransferase system (PTS). Transcription of the genes involved in mannitol uptake in this bacterium is regulated by the transcriptional regulator MtlR, a DNA-binding protein whose affinity for DNA is controlled by phosphorylation by the PTS proteins HPr and IICB(mtl). The mutational and biochemical studies presented in this report reveal that two domains of MtlR, PTS regulation domain (PRD)-I and PRD-II, are phosphorylated by HPr, whereas a third IIA-like domain is phosphorylated by IICB(mtl). An involvement of PRD-I and the IIA-like domain in a decrease in affinity of MtlR for DNA and of PRD-II in an increase in affinity is demonstrated by DNA footprint experiments using MtlR mutants. Since both PRD-I and PRD-II are phosphorylated by HPr, PRD-I needs to be dephosphorylated by IICB(mtl) and mannitol to obtain maximal affinity for DNA. This implies that a phosphoryl group can be transferred from HPr to IICB(mtl) via MtlR. Indeed, this transfer could be demonstrated by the phosphoenolpyruvate-dependent formation of [(3)H]mannitol phosphate in the absence of IIA(mtl). Phosphoryl transfer experiments using MtlR mutants revealed that PRD-I and PRD-II are dephosphorylated via the IIA-like domain. Complementation experiments using two mutants with no or low phosphoryl transfer activity showed that phosphoryl transfer between MtlR molecules is possible, indicating that MtlR-MtlR interactions take place. Phosphorylation of the same site by HPr and dephosphorylation by IICB(mtl) have not been described before; they could also play a role in other PRD-containing proteins.
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Affiliation(s)
- S A Henstra
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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20
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Zhuang J, Gutknecht R, Flükiger K, Hasler L, Erni B, Engel A. Purification and electron microscopic characterization of the membrane subunit (IICB(Glc)) of the Escherichia coli glucose transporter. Arch Biochem Biophys 1999; 372:89-96. [PMID: 10562420 DOI: 10.1006/abbi.1999.1458] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The glucose transporter of the bacterial phosphotransferase system mediates sugar transport across the cytoplasmic membrane concomitant with sugar phosphorylation. It consists of a cytoplasmic subunit IIA(Glc) and the transmembrane subunit IICB(Glc). IICB(Glc) was purified to homogeneity by urea/alkali washing of membranes and nickel-chelate affinity chromatography. About 1.5 mg highly pure IICB(Glc) representing 77% of the total activity present in the membranes was obtained from 8g (wet weight) of cells. IICB(Glc) was reconstituted into lipid bilayers by temperature-controlled dialysis to yield small 2D crystals and by a rapid detergent-dilution procedure to yield densely packed vesicles. Electron microscopy and digital image processing of the negatively stained 2D crystals revealed a trigonal lattice with a unit cell size of a = b = 14.5 nm. The unit cell morphology exhibited three dimers of IICB(Glc) surrounding the threefold symmetry center. Single particle analysis of IICB(Glc) in proteoliposomes obtained by detergent dialysis also showed predominantly dimeric structures.
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Affiliation(s)
- J Zhuang
- M. E. Müller-Institute for Microscopic Structural Biology at the Biocenter, University of Basel, Klingelbergstrasse 70, Basel, CH-4056, Switzerland.
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21
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Pfeiffer R, Loffing J, Rossier G, Bauch C, Meier C, Eggermann T, Loffing-Cueni D, Kühn LC, Verrey F. Luminal heterodimeric amino acid transporter defective in cystinuria. Mol Biol Cell 1999; 10:4135-47. [PMID: 10588648 PMCID: PMC25748 DOI: 10.1091/mbc.10.12.4135] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mutations of the glycoprotein rBAT cause cystinuria type I, an autosomal recessive failure of dibasic amino acid transport (b(0,+) type) across luminal membranes of intestine and kidney cells. Here we identify the permease-like protein b(0,+)AT as the catalytic subunit that associates by a disulfide bond with rBAT to form a hetero-oligomeric b(0,+) amino acid transporter complex. We demonstrate its b(0,+)-type amino acid transport kinetics using a heterodimeric fusion construct and show its luminal brush border localization in kidney proximal tubule. These biochemical, transport, and localization characteristics as well as the chromosomal localization on 19q support the notion that the b(0,+)AT protein is the product of the gene defective in non-type I cystinuria.
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Affiliation(s)
- R Pfeiffer
- Institute of Physiology, University of Zürich, CH-8057 Zürich, Switzerland
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22
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Robillard GT, Broos J. Structure/function studies on the bacterial carbohydrate transporters, enzymes II, of the phosphoenolpyruvate-dependent phosphotransferase system. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1422:73-104. [PMID: 10393270 DOI: 10.1016/s0304-4157(99)00002-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- G T Robillard
- The University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Nienborgh 4, 9747 AG, Groningen, The Netherlands.
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23
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Chen Q, Amster-Choder O. BglF, the Escherichia coli beta-glucoside permease and sensor of the bgl system: domain requirements of the different catalytic activities. J Bacteriol 1999; 181:462-8. [PMID: 9882659 PMCID: PMC93399 DOI: 10.1128/jb.181.2.462-468.1999] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Escherichia coli BglF protein, an enzyme II of the phosphoenolpyruvate-dependent carbohydrate phosphotransferase system, has several enzymatic activities. In the absence of beta-glucosides, it phosphorylates BglG, a positive regulator of bgl operon transcription, thus inactivating BglG. In the presence of beta-glucosides, it activates BglG by dephosphorylating it and, at the same time, transports beta-glucosides into the cell and phosphorylates them. BglF is composed of two hydrophilic domains, IIAbgl and IIBbgl, and a membrane-bound domain, IICbgl, which are covalently linked in the order IIBCAbgl. Cys-24 in the IIBbgl domain is essential for all the phosphorylation and dephosphorylation activities of BglF. We have investigated the domain requirement of the different functions carried out by BglF. To this end, we cloned the individual BglF domains, as well as the domain pairs IIBCbgl and IICAbgl, and tested which domains and which combinations are required for the catalysis of the different functions, both in vitro and in vivo. We show here that the IIB and IIC domains, linked to each other (IIBCbgl), are required for the sugar-driven reactions, i. e., sugar phosphotransfer and BglG activation by dephosphorylation. In contrast, phosphorylated IIBbgl alone can catalyze BglG inactivation by phosphorylation. Thus, the sugar-induced and noninduced functions have different structural requirements. Our results suggest that catalysis of the sugar-induced functions depends on specific interactions between IIBbgl and IICbgl which occur upon the interaction of BglF with the sugar.
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Affiliation(s)
- Q Chen
- Department of Molecular Biology, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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24
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Gutknecht R, Manni M, Mao Q, Erni B. The glucose transporter of Escherichia coli with circularly permuted domains is active in vivo and in vitro. J Biol Chem 1998; 273:25745-50. [PMID: 9748244 DOI: 10.1074/jbc.273.40.25745] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterial phosphotransferase system (PTS) consists of two energy-coupling soluble proteins (enzyme I and HPr) and a large number of inner membrane transporters (enzymes II) that mediate concomitant phosphorylation and translocation of sugars and hexitols. The transporters consist of three functional units (IIA, IIB, IIC), which occur either as protein subunits or domains of a multidomain polypeptide. The membrane-spanning IIC domain contains the substrate binding site; IIA and IIB are phosphorylation domains that transfer phosphate from HPr to the transported sugar. The transporter complexes of the PTS are good examples for variation of design by modular assembly of domains and subunits. The domain order is IIC-IIB in the membrane subunit of the Escherichia coli glucose transporter (IICBGlc) and IIB-IIC in Salmonella typhimurium sucrose transporter (IIBCScr). The phosphorylation domain of IICBGlc was translocated from the carboxyl-terminal to the amino-terminal end of the IIC domain, and the activity of the circularly permuted form was optimized by variation of the length and the composition of the interdomain linker. IIBapCGlc with an alanine-proline-rich interdomain linker has 70% of the control specific activity after purification and reconstitution into proteoliposomes. These results indicate that the amino-terminal end of IICBGlc must be on the cytoplasmic side of the inner membrane, that membrane insertion of the IIC domain is insensitive to the modification of its amino-terminal end, and that a domain swap as it could occur by a single DNA translocation event can rapidly lead to a functional protein. However, IIB could not be substituted for by glucokinase. Fusion proteins between the IIC domain and glucokinase do not transport and phosphorylate glucose in an ATP-dependent mechanism, although the IIC moiety displays transport activity upon complementation with soluble subclonal IIB, and the glucokinase moiety retains ATP-dependent nonvectorial kinase activity. This indicates that IIC and IIB are two cooperative units and not only sequentially acting upon a common substrate, and that translocation of glucose must be conformationally coupled to the phosphorylation/dephosphorylation cycle of IIB.
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Affiliation(s)
- R Gutknecht
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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25
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Rohwer JM, Postma PW, Kholodenko BN, Westerhoff HV. Implications of macromolecular crowding for signal transduction and metabolite channeling. Proc Natl Acad Sci U S A 1998; 95:10547-52. [PMID: 9724740 PMCID: PMC27931 DOI: 10.1073/pnas.95.18.10547] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The effect of different total enzyme concentrations on the flux through the bacterial phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) in vitro was determined by measuring PTS-mediated carbohydrate phosphorylation at different dilutions of cell-free extract of Escherichia coli. The dependence of the flux on the protein concentration was more than linear but less than quadratic. The combined flux-response coefficient of the four enzymes constituting the glucose PTS decreased slightly from values of approximately 1.8 with increasing protein concentrations in the assay. Addition of the macromolecular crowding agents polyethylene glycol (PEG) 6000 and PEG 35000 led to a sharper decrease in the combined flux-response coefficient, in one case to values of approximately 1. PEG 6000 stimulated the PTS flux at lower protein concentrations and inhibited the flux at higher protein concentrations, with the transition depending on the PEG 6000 concentration. This suggests that macromolecular crowding decreases the dissociation rate constants of enzyme complexes. High concentrations of the microsolute glycerol did not affect the combined flux-response coefficient. The data could be explained with a kinetic model of macromolecular crowding in a two-enzyme group-transfer pathway. Our results suggest that, because of the crowded environment in the cell, the different PTS enzymes form complexes that live long on the time-scale of their turnover. The implications for the metabolic behavior and control properties of the PTS, and for the effect of macromolecular crowding on nonequilibrium processes, are discussed.
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Affiliation(s)
- J M Rohwer
- E.C. Slater Institute, BioCentrum Amsterdam, University of Amsterdam, Plantage Muidergracht 12, NL-1018 TV Amsterdam, The Netherlands
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26
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Huang P, Liu Q, Scarborough GA. Lysophosphatidylglycerol: a novel effective detergent for solubilizing and purifying the cystic fibrosis transmembrane conductance regulator. Anal Biochem 1998; 259:89-97. [PMID: 9606148 DOI: 10.1006/abio.1998.2633] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Similar to the recombinant cystic fibrosis transmembrane conductance regulator (CFTR) expressed in Sf9 insect cells, underglycosylated CFTR expressed in yeast is not effectively solubilized by a variety of commonly used detergents, requiring instead harsh alkali and SDS treatments, which would denature most proteins. Moreover, solubilized CFTR has a strong tendency to aggregate and form high-molecular-weight aggregates during subsequent purification. We report here that the mild detergent, lysophosphatidylglycerol (LPG), is a very effective detergent for solubilizing the CFTR expressed in both yeast and Sf9 insect cells. LPG solubilizes nearly 100% of the CFTR in yeast in the absence of NaCl and none in the presence of 1 M NaCl. It is also very potent in preventing aggregation of the CFTR during subsequent purification. Exploiting these characteristics, a rapid simple procedure for the purification of functional recombinant CFTR expressed in yeast has been developed. It includes selective CFTR solubilization in the presence and the absence of NaCl followed by nickel-chelate chromatography of His-tagged CFTR. The CFTR produced by this procedure is about 70% pure. Purified CFTR molecules were reconstituted into liposomes and then fused to planar lipid bilayers for single-channel recording. The reconstituted CFTR exhibits regulatory chloride channel activities with a slope conductance of 7.1 pS and a reversal potential of -32 mV. The effectiveness and simplicity of this new purification procedure for the CFTR should greatly facilitate a variety of biochemical and biophysical studies of this important protein. Furthermore, the potency of LPG in solubilizing the notoriously intractable underglycosylated CFTR suggest that this detergent may be useful for solubilizing the CFTR from other sources and for other difficult membrane proteins as well.
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Affiliation(s)
- P Huang
- Department of Pharmacology, University of North Carolina, Chapel Hill 27599, USA
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27
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Mao Q, Scarborough GA. Purification of functional human P-glycoprotein expressed in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1327:107-18. [PMID: 9247172 DOI: 10.1016/s0005-2736(97)00050-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A system for expression and facile purification of the human P-glycoprotein (Pgp) from the yeast Saccharomyces cerevisiae is described. The wild-type human mdr1 cDNA was cloned into a high copy number yeast expression vector under the control of the constitutive promoter of the yeast plasma membrane H+-ATPase. Western blots of membranes from the stable transformants confirmed that the Pgp is expressed in yeast cells in amounts approximately 0.4% of the total yeast membrane protein. Density gradient sedimentation analysis of the yeast membranes indicated that the expressed Pgp is localized in the plasma membrane. Yeast cells transformed with the Pgp expression plasmid acquire increased resistance to valinomycin, suggesting that the expressed Pgp is properly folded and functional. The expressed Pgp can be solubilized from the yeast membranes with lysophosphatidylcholine, and when tagged with ten histidines at its C-terminus, can be readily purified to about 90% homogeneity by Ni2+ affinity chromatography. About 50 microg of the Pgp can be purified from 20 mg of crude yeast membranes. The purified human Pgp exhibits a verapamil-stimulated ATPase activity and the maximal activity is 2.5 +/- 0.5 micromol/min per mg of Pgp, suggesting that the purified Pgp from yeast is highly functional. The Pgp expressed in yeast has the same electrophoretic mobility (ca. 130 kDa) as the Pgp produced in Sf9 insect cells and is unaffected by N-glycosidase treatment, suggesting that it is not glycosylated. Because of the relative ease of growing yeast in massive quantities this expression system appears to be excellent for producing this membrane transporter at levels sufficient for further biochemical and biophysical studies, and for site-directed mutagenesis studies as well.
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Affiliation(s)
- Q Mao
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill 27599, USA
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28
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Abstract
Recent phylogenetic and structural analyses of multidomain phosphoryl transfer proteins of bacteria have revealed that interdomain (but not intradomain) splicing and fusion, as well as domain duplication and deletion, have occurred frequently during evolution. These events have been found to be exceedingly rare in certain other protein families. Domain-shuffling events are illustrated by examples from the superfamilies of phosphoenolpyruvate-dependent sugar phosphotransferase systems, their transcriptional regulatory protein targets of phosphorylation, sensor autokinase/response regulator signal transduction systems, and permeases of the ATP-binding-cassette type.
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Affiliation(s)
- J Reizer
- Department of Biology, University of California at San Diego, La Jolla, 92093-0116, USA.
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