1
|
Soria S, Carreón-Rodríguez OE, de Anda R, Flores N, Escalante A, Bolívar F. Transcriptional and Metabolic Response of a Strain of Escherichia coli PTS - to a Perturbation of the Energetic Level by Modification of [ATP]/[ADP] Ratio. BIOTECH 2024; 13:10. [PMID: 38651490 PMCID: PMC11036233 DOI: 10.3390/biotech13020010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/06/2024] [Accepted: 04/08/2024] [Indexed: 04/25/2024] Open
Abstract
The intracellular [ATP]/[ADP] ratio is crucial for Escherichia coli's cellular functions, impacting transport, phosphorylation, signaling, and stress responses. Overexpression of F1-ATPase genes in E. coli increases glucose consumption, lowers energy levels, and triggers transcriptional responses in central carbon metabolism genes, particularly glycolytic ones, enhancing carbon flux. In this contribution, we report the impact of the perturbation of the energetic level in a PTS- mutant of E. coli by modifying the [ATP]/[ADP] ratio by uncoupling the cytoplasmic activity of the F1 subunit of the ATP synthase. The disruption of [ATP]/[ADP] ratio in the evolved strain of E. coli PB12 (PTS-) was achieved by the expression of the atpAGD operon encoding the soluble portion of ATP synthase F1-ATPase (strain PB12AGD+). The analysis of the physiological and metabolic response of the PTS- strain to the ATP disruption was determined using RT-qPCR of 96 genes involved in glucose and acetate transport, glycolysis and gluconeogenesis, pentose phosphate pathway (PPP), TCA cycle and glyoxylate shunt, several anaplerotic, respiratory chain, and fermentative pathways genes, sigma factors, and global regulators. The apt mutant exhibited reduced growth despite increased glucose transport due to decreased energy levels. It heightened stress response capabilities under glucose-induced energetic starvation, suggesting that the carbon flux from glycolysis is distributed toward the pentose phosphate and the Entner-Duodoroff pathway with the concomitant. Increase acetate transport, production, and utilization in response to the reduction in the [ATP]/[ADP] ratio. Upregulation of several genes encoding the TCA cycle and the glyoxylate shunt as several respiratory genes indicates increased respiratory capabilities, coupled possibly with increased availability of electron donor compounds from the TCA cycle, as this mutant increased respiratory capability by 240% more than in the PB12. The reduction in the intracellular concentration of cAMP in the atp mutant resulted in a reduced number of upregulated genes compared to PB12, suggesting that the mutant remains a robust genetic background despite the severe disruption in its energetic level.
Collapse
Affiliation(s)
- Sandra Soria
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
- Laboratorio de Soluciones Biotecnológicas (LasoBiotc), Montevideo 11800, Uruguay
| | - Ofelia E. Carreón-Rodríguez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
| | - Ramón de Anda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
| | - Noemí Flores
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
| | - Adelfo Escalante
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
| | - Francisco Bolívar
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Mexico; (S.S.); (O.E.C.-R.); (R.d.A.); (N.F.)
| |
Collapse
|
2
|
Royes J, Talbot P, Le Bon C, Moncoq K, Uzan M, Zito F, Miroux B. Membrane Protein Production in Escherichia coli: Protocols and Rules. Methods Mol Biol 2022; 2507:19-39. [PMID: 35773575 DOI: 10.1007/978-1-0716-2368-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Despite recent progresses in the use of eukaryotic expression system, production of membrane proteins for structural studies still relies on microbial expression systems. In this review, we provide protocols to achieve high level expression of membrane proteins in Escherichia coli, especially using the T7 RNA polymerase based expression system. From the design of the construct, the choice of the appropriate vector-host combination, the assessment of the bacterial fitness, to the selection of bacterial mutant adapted to the production of the target membrane protein, the chapter covers all necessary methods for a rapid optimization of a specific target membrane protein. In addition, we provide a protocol for membrane protein solubilization based on our recent analysis of the Protein Data Bank.
Collapse
Affiliation(s)
- Jordi Royes
- Laboratoire de Colloïdes et Matériaux Divisés École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris 10, Paris, France
| | - Pauline Talbot
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France
| | - Christel Le Bon
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France
| | - Karine Moncoq
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France
| | - Marc Uzan
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France
| | - Francesca Zito
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France
| | - Bruno Miroux
- Université Paris Cité, CNRS, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, Paris, France.
| |
Collapse
|
3
|
Activation of metabolic and stress responses during subtoxic expression of the type I toxin hok in Erwinia amylovora. BMC Genomics 2021; 22:74. [PMID: 33482720 PMCID: PMC7821729 DOI: 10.1186/s12864-021-07376-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 01/08/2021] [Indexed: 11/15/2022] Open
Abstract
Background Toxin-antitoxin (TA) systems, abundant in prokaryotes, are composed of a toxin gene and its cognate antitoxin. Several toxins are implied to affect the physiological state and stress tolerance of bacteria in a population. We previously identified a chromosomally encoded hok-sok type I TA system in Erwinia amylovora, the causative agent of fire blight disease on pome fruit trees. A high-level induction of the hok gene was lethal to E. amylovora cells through unknown mechanisms. The molecular targets or regulatory roles of Hok were unknown. Results Here, we examined the physiological and transcriptomic changes of Erwinia amylovora cells expressing hok at subtoxic levels that were confirmed to confer no cell death, and at toxic levels that resulted in killing of cells. In both conditions, hok caused membrane rupture and collapse of the proton motive force in a subpopulation of E. amylovora cells. We demonstrated that induction of hok resulted in upregulation of ATP biosynthesis genes, and caused leakage of ATP from cells only at toxic levels. We showed that overexpression of the phage shock protein gene pspA largely reversed the cell death phenotype caused by high levels of hok induction. We also showed that induction of hok at a subtoxic level rendered a greater proportion of stationary phase E. amylovora cells tolerant to the antibiotic streptomycin. Conclusions We characterized the molecular mechanism of toxicity by high-level of hok induction and demonstrated that low-level expression of hok primes the stress responses of E. amylovora against further membrane and antibiotic stressors. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07376-w.
Collapse
|
4
|
Biophysical characterization and stabilization of detergent-solubilized lipoprotein N-acyl transferase from P. aeruginosa and E. coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1384-1393. [PMID: 29573991 DOI: 10.1016/j.bbamem.2018.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/18/2018] [Accepted: 03/20/2018] [Indexed: 11/23/2022]
Abstract
Lipoproteins are important for bacterial growth and virulence and interest in them as targets for antibiotic development is growing. Lipoprotein N-acyl transferase (Lnt) catalyzes the final step in the lipoprotein posttranslational processing pathway. The mature lipoprotein can remain in the inner membrane or be trafficked to the outer membrane in the case of diderm prokaryotes. With a view to obtaining high-resolution crystal structures of membrane integral Lnt for use in drug discovery a program was undertaken to generate milligram quantities of stable, homogenous and functional protein. This involved screening across bacterial species for suitable orthologues and optimization at the level of protein expression, solubilization and stability. Combining biophysical and functional characterization, orthologous Lnt from Escherichia coli and the opportunistic human pathogen Pseudomonas aeruginosa was identified as suitable for the proposed structure determination campaign that ultimately yielded crystal structures. The rational approaches taken that eventually provided structure-quality protein are presented in this report.
Collapse
|
5
|
Abstract
Functional and structural studies on membrane proteins are limited by the difficulty to produce them in large amount and in a functional state. In this review, we provide protocols to achieve high-level expression of membrane proteins in Escherichia coli. The T7 RNA polymerase-based expression system is presented in detail and protocols to assess and improve its efficiency are discussed. Protocols to isolate either membrane or inclusion bodies and to perform an initial qualitative test to assess the solubility of the recombinant protein are also included.
Collapse
|
6
|
Expression and immunological cross-reactivity of LALP3, a novel astacin-like metalloprotease from brown spider (Loxosceles intermedia) venom. Biochimie 2016; 128-129:8-19. [PMID: 27343628 DOI: 10.1016/j.biochi.2016.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/06/2016] [Indexed: 12/14/2022]
Abstract
Loxosceles spiders' venom comprises a complex mixture of biologically active toxins, mostly consisting of low molecular mass components (2-40 kDa). Amongst, isoforms of astacin-like metalloproteases were identified through transcriptome and proteome analyses. Only LALP1 (Loxosceles Astacin-Like protease 1) has been characterized. Herein, we characterized LALP3 as a novel recombinant astacin-like metalloprotease isoform from Loxosceles intermedia venom. LALP3 cDNA was cloned in pET-SUMO vector, and its soluble heterologous expression was performed using a SUMO tag added to LALP3 to achieve solubility in Escherichia coli SHuffle T7 Express LysY cells, which express the disulfide bond isomerase DsbC. Protein purification was conducted by Ni-NTA Agarose resin and assayed for purity by SDS-PAGE under reducing conditions. Immunoblotting analyses were performed with specific antibodies recognizing LALP1 and whole venom. Western blotting showed linear epitopes from recombinant LALP3 that cross-reacted with LALP1, and dot blotting revealed conformational epitopes with native venom astacins. Mass spectrometry analysis revealed that the recombinant expressed protein is an astacin-like metalloprotease from L. intermedia venom. Furthermore, molecular modeling of LALP3 revealed that this isoform contains the zinc binding and Met-turn motifs, forming the active site, as has been observed in astacins. These data confirmed that LALP3, which was successfully obtained by heterologous expression using a prokaryote system, is a new astacin-like metalloprotease isoform present in L. intermedia venom.
Collapse
|
7
|
Ben Azoun S, Ben Zakour M, Sghaier S, Kallel H. Expression of rabies virus glycoprotein in the methylotrophic yeast Pichia pastoris. Biotechnol Appl Biochem 2016; 64:50-61. [PMID: 28218973 DOI: 10.1002/bab.1471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 12/14/2015] [Indexed: 11/10/2022]
Abstract
Rabies is a fatal disease that can be prevented by vaccination. Different approaches were investigated to develop novel human rabies vaccines with improved features compared to the current available vaccines, among them is the use of heterologous gene expression technology. Here, we describe the expression of the surface rabies virus glycoprotein (RABV-G), which is the major antigen responsible for the induction of protective immunity, in Pichia pastoris. Six transformants were selected according to their gene copy number as determined by real time qPCR. Upon induction by methanol, low level of RABV-G was secreted into the culture medium, around 60 ng/mL. To understand the effect of foreign gene dosage on cellular physiology of P. pastoris, transcriptional analysis of key genes involved in unfolded protein response (UPR) and endoplasmic reticulum associated degradation (ERAD) pathway was performed. Results showed that these pathways were highly activated; misfolded RABV-G was degraded in the cytosol via the ERAD mechanism. To study the functionality of the secreted RABV-G, in vitro competitive neutralizing assay was conducted. Data showed the secreted recombinant RABV-G had enabled a reduction of the neutralizing activity of human immune rabies serum, indicating that the secreted recombinant protein had reached its correct conformational form.
Collapse
Affiliation(s)
- Safa Ben Azoun
- Laboratory of Molecular Microbiology, Vaccinology and Biotechnology Development, Biofermentation Unit, Institut Pasteur de Tunis, Tunis, Tunisia
| | - Meriem Ben Zakour
- Laboratory of Molecular Microbiology, Vaccinology and Biotechnology Development, Biofermentation Unit, Institut Pasteur de Tunis, Tunis, Tunisia
| | - Soufien Sghaier
- Institut de Recherche, Vétérinaire de Tunisie, Tunis, Tunisia
| | - Héla Kallel
- Laboratory of Molecular Microbiology, Vaccinology and Biotechnology Development, Biofermentation Unit, Institut Pasteur de Tunis, Tunis, Tunisia
| |
Collapse
|
8
|
Snijder HJA, Hakulinen J. Membrane Protein Production in E. coli for Applications in Drug Discovery. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 896:59-77. [PMID: 27165319 DOI: 10.1007/978-3-319-27216-0_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Producing high quality purified membrane proteins for structure-based drug design and biophysical assays compatible with typical timelines in drug discovery is a significant challenge. Escherichia coli has been an expression host of the utmost importance for soluble proteins and has applications for membrane proteins as well. However, membrane protein overexpression in E. coli may lead to toxicity and low yields of functional product. Here, we review the challenges encountered with heterologous overproduction of α-helical membrane proteins in E. coli and a range of strategies to overcome them. A detailed protocol is also provided for expression and screening of membrane proteins in E. coli using a His-specific fluorescent probe and fluorescent size-exclusion chromatography.
Collapse
Affiliation(s)
| | - Jonna Hakulinen
- Discovery Sciences, AstraZeneca R&D, SE-43183, Mölndal, Sweden
| |
Collapse
|
9
|
Abstract
The F1F0-ATP synthase (EC 3.6.1.34) is a remarkable enzyme that functions as a rotary motor. It is found in the inner membranes of Escherichia coli and is responsible for the synthesis of ATP in response to an electrochemical proton gradient. Under some conditions, the enzyme functions reversibly and uses the energy of ATP hydrolysis to generate the gradient. The ATP synthase is composed of eight different polypeptide subunits in a stoichiometry of α3β3γδεab2c10. Traditionally they were divided into two physically separable units: an F1 that catalyzes ATP hydrolysis (α3β3γδε) and a membrane-bound F0 sector that transports protons (ab2c10). In terms of rotary function, the subunits can be divided into rotor subunits (γεc10) and stator subunits (α3β3δab2). The stator subunits include six nucleotide binding sites, three catalytic and three noncatalytic, formed primarily by the β and α subunits, respectively. The stator also includes a peripheral stalk composed of δ and b subunits, and part of the proton channel in subunit a. Among the rotor subunits, the c subunits form a ring in the membrane, and interact with subunit a to form the proton channel. Subunits γ and ε bind to the c-ring subunits, and also communicate with the catalytic sites through interactions with α and β subunits. The eight subunits are expressed from a single operon, and posttranscriptional processing and translational regulation ensure that the polypeptides are made at the proper stoichiometry. Recent studies, including those of other species, have elucidated many structural and rotary properties of this enzyme.
Collapse
|
10
|
Hattab G, Warschawski DE, Moncoq K, Miroux B. Escherichia coli as host for membrane protein structure determination: a global analysis. Sci Rep 2015; 5:12097. [PMID: 26160693 PMCID: PMC4498379 DOI: 10.1038/srep12097] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/11/2015] [Indexed: 11/13/2022] Open
Abstract
The structural biology of membrane proteins (MP) is hampered by the difficulty in producing and purifying them. A comprehensive analysis of protein databases revealed that 213 unique membrane protein structures have been obtained after production of the target protein in E. coli. The primary expression system used was the one based on the T7 RNA polymerase, followed by the arabinose and T5 promoter based expression systems. The C41λ(DE3) and C43λ(DE3) bacterial mutant hosts have contributed to 28% of non E. coli membrane protein structures. A large scale analysis of expression protocols demonstrated a preference for a combination of bacterial host-vector together with a bimodal distribution of induction temperature and of inducer concentration. Altogether our analysis provides a set of rules for the optimal use of bacterial expression systems in membrane protein production.
Collapse
Affiliation(s)
- Georges Hattab
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS, Univ Paris Diderot, Sorbonne Paris Cité, PSL research university, Paris, France
| | - Dror E Warschawski
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS, Univ Paris Diderot, Sorbonne Paris Cité, PSL research university, Paris, France
| | - Karine Moncoq
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS, Univ Paris Diderot, Sorbonne Paris Cité, PSL research university, Paris, France
| | - Bruno Miroux
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS, Univ Paris Diderot, Sorbonne Paris Cité, PSL research university, Paris, France
| |
Collapse
|
11
|
Putative Inv is essential for basolateral invasion of Caco-2 cells and acts synergistically with OmpA to affect in vitro and in vivo virulence of Cronobacter sakazakii ATCC 29544. Infect Immun 2014; 82:1755-65. [PMID: 24549330 DOI: 10.1128/iai.01397-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cronobacter sakazakii is an opportunistic pathogen that causes neonatal meningitis and necrotizing enterocolitis. Its interaction with intestinal epithelium is important in the pathogenesis of enteric infections. In this study, we investigated the involvement of the inv gene in the virulence of C. sakazakii ATCC 29544 in vitro and in vivo. Sequence analysis of C. sakazakii ATCC 29544 inv revealed that it is different from other C. sakazakii isolates. In various cell culture models, an Δinv deletion mutant showed significantly lowered invasion efficiency, which was restored upon genetic complementation. Studying invasion potentials using tight-junction-disrupted Caco-2 cells suggested that the inv gene product mediates basolateral invasion of C. sakazakii ATCC 29544. In addition, comparison of invasion potentials of double mutant (ΔompA Δinv) and single mutants (ΔompA and Δinv) provided evidence for an additive effect of the two putative outer membrane proteins. Finally, the importance of inv and the additive effect of putative Inv and OmpA were also proven in an in vivo rat pup model. This report is the first to demonstrate two proteins working synergistically in vitro, as well as in vivo in C. sakazakii pathogenesis.
Collapse
|
12
|
Papaneophytou CP, Kontopidis G. Statistical approaches to maximize recombinant protein expression in Escherichia coli: a general review. Protein Expr Purif 2013; 94:22-32. [PMID: 24211770 DOI: 10.1016/j.pep.2013.10.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 11/16/2022]
Abstract
The supply of many valuable proteins that have potential clinical or industrial use is often limited by their low natural availability. With the modern advances in genomics, proteomics and bioinformatics, the number of proteins being produced using recombinant techniques is exponentially increasing and seems to guarantee an unlimited supply of recombinant proteins. The demand of recombinant proteins has increased as more applications in several fields become a commercial reality. Escherichia coli (E. coli) is the most widely used expression system for the production of recombinant proteins for structural and functional studies. However, producing soluble proteins in E. coli is still a major bottleneck for structural biology projects. One of the most challenging steps in any structural biology project is predicting which protein or protein fragment will express solubly and purify for crystallographic studies. The production of soluble and active proteins is influenced by several factors including expression host, fusion tag, induction temperature and time. Statistical designed experiments are gaining success in the production of recombinant protein because they provide information on variable interactions that escape the "one-factor-at-a-time" method. Here, we review the most important factors affecting the production of recombinant proteins in a soluble form. Moreover, we provide information about how the statistical design experiments can increase protein yield and purity as well as find conditions for crystal growth.
Collapse
Affiliation(s)
- Christos P Papaneophytou
- Veterinary School, University of Thessaly, Trikalon 224, Karditsa 43100, Greece; Institute for Research and Technology - Thessaly (I.RE.TE.TH.), The Centre for Research & Technology Hellas (CE.R.TH.), Technology Park of Thessaly, 1st Industrial Area, Volos 38500, Greece
| | - George Kontopidis
- Veterinary School, University of Thessaly, Trikalon 224, Karditsa 43100, Greece; Institute for Research and Technology - Thessaly (I.RE.TE.TH.), The Centre for Research & Technology Hellas (CE.R.TH.), Technology Park of Thessaly, 1st Industrial Area, Volos 38500, Greece.
| |
Collapse
|
13
|
Zhang C, Allegretti M, Vonck J, Langer JD, Marcia M, Peng G, Michel H. Production of fully assembled and active Aquifex aeolicus F1FO ATP synthase in Escherichia coli. Biochim Biophys Acta Gen Subj 2013; 1840:34-40. [PMID: 24005236 DOI: 10.1016/j.bbagen.2013.08.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/13/2013] [Accepted: 08/27/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND F1FO ATP synthases catalyze the synthesis of ATP from ADP and inorganic phosphate driven by ion motive forces across the membrane. A number of ATP synthases have been characterized to date. The one from the hyperthermophilic bacterium Aquifex aeolicus presents unique features, i.e. a putative heterodimeric stalk. To complement previous work on the native form of this enzyme, we produced it heterologously in Escherichia coli. METHODS We designed an artificial operon combining the nine genes of A. aeolicus ATP synthase, which are split into four clusters in the A. aeolicus genome. We expressed the genes and purified the enzyme complex by affinity and size-exclusion chromatography. We characterized the complex by native gel electrophoresis, Western blot, and mass spectrometry. We studied its activity by enzymatic assays and we visualized its structure by single-particle electron microscopy. RESULTS We show that the heterologously produced complex has the same enzymatic activity and the same structure as the native ATP synthase complex extracted from A. aeolicus cells. We used our expression system to confirm that A. aeolicus ATP synthase possesses a heterodimeric peripheral stalk unique among non-photosynthetic bacterial F1FO ATP synthases. CONCLUSIONS Our system now allows performing previously impossible structural and functional studies on A. aeolicus F1FO ATP synthase. GENERAL SIGNIFICANCE More broadly, our work provides a valuable platform to characterize many other membrane protein complexes with complicated stoichiometry, i.e. other respiratory complexes, the nuclear pore complex, or transporter systems.
Collapse
Affiliation(s)
- Chunli Zhang
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
| | | | | | | | | | | | | |
Collapse
|
14
|
Time-delayed in vivo assembly of subunit a into preformed Escherichia coli FoF1 ATP synthase. J Bacteriol 2013; 195:4074-84. [PMID: 23836871 DOI: 10.1128/jb.00468-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Escherichia coli F(O)F(1) ATP synthase, a rotary nanomachine, is composed of eight different subunits in a α3β3γδεab2c10 stoichiometry. Whereas F(O)F(1) has been studied in detail with regard to its structure and function, much less is known about how this multisubunit enzyme complex is assembled. Single-subunit atp deletion mutants are known to be arrested in assembly, thus leading to formation of partially assembled subcomplexes. To determine whether those subcomplexes are preserved in a stable standby mode, a time-delayed in vivo assembly system was developed. To establish this approach, we targeted the time-delayed assembly of membrane-integrated subunit a into preformed F(O)F(1) lacking subunit a (F(O)F(1)-a) which is known to form stable subcomplexes in vitro. Two expression systems (araBADp and T7p-laco) were adjusted to provide compatible, mutually independent, and sufficiently stringent induction and repression regimens. In detail, all structural atp genes except atpB (encoding subunit a) were expressed under the control of araBADp and induced by arabinose. Following synthesis of F(O)F(1)-a during growth, expression was repressed by glucose/d-fucose, and degradation of atp mRNA controlled by real-time reverse transcription-PCR. A time-delayed expression of atpB under T7p-laco control was subsequently induced in trans by addition of isopropyl-β-d-thiogalactopyranoside. Formation of fully assembled, and functional, F(O)F(1) complexes was verified. This demonstrates that all subunits of F(O)F(1)-a remain in a stable preformed state capable to integrate subunit a as the last subunit. The results reveal that the approach presented here can be applied as a general method to study the assembly of heteromultimeric protein complexes in vivo.
Collapse
|
15
|
Current state and recent advances in biopharmaceutical production in Escherichia coli, yeasts and mammalian cells. J Ind Microbiol Biotechnol 2013; 40:257-74. [PMID: 23385853 DOI: 10.1007/s10295-013-1235-0] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 01/22/2013] [Indexed: 12/28/2022]
Abstract
Almost all of the 200 or so approved biopharmaceuticals have been produced in one of three host systems: the bacterium Escherichia coli, yeasts (Saccharomyces cerevisiae, Pichia pastoris) and mammalian cells. We describe the most widely used methods for the expression of recombinant proteins in the cytoplasm or periplasm of E. coli, as well as strategies for secreting the product to the growth medium. Recombinant expression in E. coli influences the cell physiology and triggers a stress response, which has to be considered in process development. Increased expression of a functional protein can be achieved by optimizing the gene, plasmid, host cell, and fermentation process. Relevant properties of two yeast expression systems, S. cerevisiae and P. pastoris, are summarized. Optimization of expression in S. cerevisiae has focused mainly on increasing the secretion, which is otherwise limiting. P. pastoris was recently approved as a host for biopharmaceutical production for the first time. It enables high-level protein production and secretion. Additionally, genetic engineering has resulted in its ability to produce recombinant proteins with humanized glycosylation patterns. Several mammalian cell lines of either rodent or human origin are also used in biopharmaceutical production. Optimization of their expression has focused on clonal selection, interference with epigenetic factors and genetic engineering. Systemic optimization approaches are applied to all cell expression systems. They feature parallel high-throughput techniques, such as DNA microarray, next-generation sequencing and proteomics, and enable simultaneous monitoring of multiple parameters. Systemic approaches, together with technological advances such as disposable bioreactors and microbioreactors, are expected to lead to increased quality and quantity of biopharmaceuticals, as well as to reduced product development times.
Collapse
|
16
|
Pierson HE, Uhlemann EME, Dmitriev OY. Interaction with monomeric subunit c drives insertion of ATP synthase subunit a into the membrane and primes a-c complex formation. J Biol Chem 2011; 286:38583-38591. [PMID: 21900248 DOI: 10.1074/jbc.m111.294868] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit a is the main part of the membrane stator of the ATP synthase molecular turbine. Subunit c is the building block of the membrane rotor. We have generated two molecular fusions of a and c subunits with different orientations of the helical hairpin of subunit c. The a/c fusion protein with correct orientation of transmembrane helices was inserted into the membrane, and co-incorporated into the F(0) complex of ATP synthase with wild type subunit c. The fused c subunit was incorporated into the c-ring tethering the ATP synthase rotor to the stator. The a/c fusion with incorrect orientation of the c-helices required wild type subunit c for insertion into the membrane. In this case, the fused c subunit remained on the periphery of the c-ring and did not interfere with rotor movement. Wild type subunit a inserted into the membrane equally well with wild type subunit c and c-ring assembly mutants that remained monomeric in the membrane. These results show that interaction with monomeric subunit c triggers insertion of subunit a into the membrane, and initiates formation of the a-c complex, the ion-translocating module of the ATP synthase. Correct assembly of the ATP synthase incorporating topologically correct fusion of subunits a and c validates using this model protein for high resolution structural studies of the ATP synthase proton channel.
Collapse
Affiliation(s)
- Hannah E Pierson
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Eva-Maria E Uhlemann
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Oleg Y Dmitriev
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| |
Collapse
|
17
|
Nørholm MHH, Light S, Virkki MTI, Elofsson A, von Heijne G, Daley DO. Manipulating the genetic code for membrane protein production: what have we learnt so far? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1091-6. [PMID: 21884679 DOI: 10.1016/j.bbamem.2011.08.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 08/04/2011] [Accepted: 08/15/2011] [Indexed: 12/19/2022]
Abstract
With synthetic gene services, molecular cloning is as easy as ordering a pizza. However choosing the right RNA code for efficient protein production is less straightforward, more akin to deciding on the pizza toppings. The possibility to choose synonymous codons in the gene sequence has ignited a discussion that dates back 50 years: Does synonymous codon use matter? Recent studies indicate that replacement of particular codons for synonymous codons can improve expression in homologous or heterologous hosts, however it is not always successful. Furthermore it is increasingly apparent that membrane protein biogenesis can be codon-sensitive. Single synonymous codon substitutions can influence mRNA stability, mRNA structure, translational initiation, translational elongation and even protein folding. Synonymous codon substitutions therefore need to be carefully evaluated when membrane proteins are engineered for higher production levels and further studies are needed to fully understand how to select the codons that are optimal for higher production. This article is part of a Special Issue entitled: Protein Folding in Membranes.
Collapse
Affiliation(s)
- Morten H H Nørholm
- Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91, Sweden.
| | | | | | | | | | | |
Collapse
|
18
|
Zoonens M, Miroux B. Expression of membrane proteins at the Escherichia coli membrane for structural studies. Methods Mol Biol 2010; 601:49-66. [PMID: 20099139 DOI: 10.1007/978-1-60761-344-2_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Structural biology of membrane proteins is often limited by the first steps in obtaining sufficient yields of proteins because native sources are seldom. Heterologous systems like bacteria are then commonly employed for membrane protein over-expression. Escherichia coli is the main bacterial host used. However, overproduction of a foreign membrane protein at a non-physiological level is usually toxic for cells or leads to inclusion body formation. Those effects can be reduced by optimizing the cell growth conditions, choosing the suitable bacterial strain and expression vector, and finally co-expressing the target protein and the b-subunit of E. coli adenosine triphosphate (ATP)-synthase, which triggers the proliferation of intracytoplasmic membranes. This chapter is devoted to help the experimenter in choosing the appropriate plasmid/bacterial host combination for optimizing the amount of the target membrane protein produced in its correct folded state.
Collapse
Affiliation(s)
- Manuela Zoonens
- Université Paris, Institut de Biologie Physico-Chimique, France
| | | |
Collapse
|
19
|
Kol S, Majczak W, Heerlien R, van der Berg JP, Nouwen N, Driessen AJM. Subunit a of the F(1)F(0) ATP synthase requires YidC and SecYEG for membrane insertion. J Mol Biol 2009; 390:893-901. [PMID: 19497329 DOI: 10.1016/j.jmb.2009.05.074] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 05/22/2009] [Accepted: 05/27/2009] [Indexed: 11/16/2022]
Abstract
The insertion of inner membrane proteins in Escherichia coli occurs almost exclusively via the SecYEG pathway, while some membrane proteins require the membrane protein insertase YidC. In vitro analysis demonstrates that subunit a of the F(1)F(0) ATP synthase (F(0)a) is strictly dependent on Ffh, SecYEG and YidC for its membrane insertion but independent of the proton motive force. The insertion of the first transmembrane segment of F(0)a also depends on Ffh and SecYEG but not on YidC, whereas the insertion is strongly dependent on the proton motive force, unlike the full-length F(0)a protein. These data demonstrate an extensive role of YidC in the assembly of the F(0) sector of the F(1)F(0) ATP synthase.
Collapse
Affiliation(s)
- Stefan Kol
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | | | | | | | | | | |
Collapse
|
20
|
Sahdev S, Khattar SK, Saini KS. Production of active eukaryotic proteins through bacterial expression systems: a review of the existing biotechnology strategies. Mol Cell Biochem 2007. [PMID: 17874175 DOI: 10.1007/s11010‐007‐9603‐6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Among the various expression systems employed for the over-production of proteins, bacteria still remains the favorite choice of a Protein Biochemist. However, even today, due to the lack of post-translational modification machinery in bacteria, recombinant eukaryotic protein production poses an immense challenge, which invariably leads to the production of biologically in-active protein in this host. A number of techniques are cited in the literature, which describe the conversion of inactive protein, expressed as an insoluble fraction, into a soluble and active form. Overall, we have divided these methods into three major groups: Group-I, where the factors influencing the formation of insoluble fraction are modified through a stringent control of the cellular milieu, thereby leading to the expression of recombinant protein as soluble moiety; Group-II, where protein is refolded from the inclusion bodies and thereby target protein modification is avoided; Group-III, where the target protein is engineered to achieve soluble expression through fusion protein technology. Even within the same family of proteins (e.g., tyrosine kinases), optimization of standard operating protocol (SOP) may still be required for each protein's over-production at a pilot-scale in Escherichia coli. However, once standardized, this procedure can be made amenable to the industrial production for that particular protein with minimum alterations.
Collapse
Affiliation(s)
- Sudhir Sahdev
- Department of Biotechnology & Bioinformatics, New Drug Discovery Research, Ranbaxy Research Laboratories-R&D-3, 20-Sector 18 Udyog Vihar, Gurgaon, India.
| | | | | |
Collapse
|
21
|
Sahdev S, Khattar SK, Saini KS. Production of active eukaryotic proteins through bacterial expression systems: a review of the existing biotechnology strategies. Mol Cell Biochem 2007; 307:249-64. [PMID: 17874175 DOI: 10.1007/s11010-007-9603-6] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 08/27/2007] [Indexed: 12/13/2022]
Abstract
Among the various expression systems employed for the over-production of proteins, bacteria still remains the favorite choice of a Protein Biochemist. However, even today, due to the lack of post-translational modification machinery in bacteria, recombinant eukaryotic protein production poses an immense challenge, which invariably leads to the production of biologically in-active protein in this host. A number of techniques are cited in the literature, which describe the conversion of inactive protein, expressed as an insoluble fraction, into a soluble and active form. Overall, we have divided these methods into three major groups: Group-I, where the factors influencing the formation of insoluble fraction are modified through a stringent control of the cellular milieu, thereby leading to the expression of recombinant protein as soluble moiety; Group-II, where protein is refolded from the inclusion bodies and thereby target protein modification is avoided; Group-III, where the target protein is engineered to achieve soluble expression through fusion protein technology. Even within the same family of proteins (e.g., tyrosine kinases), optimization of standard operating protocol (SOP) may still be required for each protein's over-production at a pilot-scale in Escherichia coli. However, once standardized, this procedure can be made amenable to the industrial production for that particular protein with minimum alterations.
Collapse
Affiliation(s)
- Sudhir Sahdev
- Department of Biotechnology & Bioinformatics, New Drug Discovery Research, Ranbaxy Research Laboratories-R&D-3, 20-Sector 18 Udyog Vihar, Gurgaon, India.
| | | | | |
Collapse
|
22
|
Marblestone JG, Edavettal SC, Lim Y, Lim P, Zuo X, Butt TR. Comparison of SUMO fusion technology with traditional gene fusion systems: enhanced expression and solubility with SUMO. Protein Sci 2006; 15:182-9. [PMID: 16322573 PMCID: PMC2242369 DOI: 10.1110/ps.051812706] [Citation(s) in RCA: 332] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 10/12/2005] [Accepted: 10/12/2005] [Indexed: 11/24/2022]
Abstract
Despite the availability of numerous gene fusion systems, recombinant protein expression in Escherichia coli remains difficult. Establishing the best fusion partner for difficult-to-express proteins remains empirical. To determine which fusion tags are best suited for difficult-to-express proteins, a comparative analysis of the newly described SUMO fusion system with a variety of commonly used fusion systems was completed. For this study, three model proteins, enhanced green fluorescent protein (eGFP), matrix metalloprotease-13 (MMP13), and myostatin (growth differentiating factor-8, GDF8), were fused to the C termini of maltose-binding protein (MBP), glutathione S-transferase (GST), thioredoxin (TRX), NUS A, ubiquitin (Ub), and SUMO tags. These constructs were expressed in E. coli and evaluated for expression and solubility. As expected, the fusion tags varied in their ability to produce tractable quantities of soluble eGFP, MMP13, and GDF8. SUMO and NUS A fusions enhanced expression and solubility of recombinant proteins most dramatically. The ease at which SUMO and NUS A fusion tags were removed from their partner proteins was then determined. SUMO fusions are cleaved by the natural SUMO protease, while an AcTEV protease site had to be engineered between NUS A and its partner protein. A kinetic analysis showed that the SUMO and AcTEV proteases had similar KM values, but SUMO protease had a 25-fold higher kcat than AcTEV protease, indicating a more catalytically efficient enzyme. Taken together, these results demonstrate that SUMO is superior to commonly used fusion tags in enhancing expression and solubility with the distinction of generating recombinant protein with native sequences.
Collapse
|
23
|
Bonander N, Hedfalk K, Larsson C, Mostad P, Chang C, Gustafsson L, Bill RM. Design of improved membrane protein production experiments: quantitation of the host response. Protein Sci 2005; 14:1729-40. [PMID: 15987902 PMCID: PMC2253360 DOI: 10.1110/ps.051435705] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Eukaryotic membrane proteins cannot be produced in a reliable manner for structural analysis. Consequently, researchers still rely on trial-and-error approaches, which most often yield insufficient amounts. This means that membrane protein production is recognized by biologists as the primary bottleneck in contemporary structural genomics programs. Here, we describe a study to examine the reasons for successes and failures in recombinant membrane protein production in yeast, at the level of the host cell, by systematically quantifying cultures in high-performance bioreactors under tightly-defined growth regimes. Our data show that the most rapid growth conditions of those chosen are not the optimal production conditions. Furthermore, the growth phase at which the cells are harvested is critical: We show that it is crucial to grow cells under tightly-controlled conditions and to harvest them prior to glucose exhaustion, just before the diauxic shift. The differences in membrane protein yields that we observe under different culture conditions are not reflected in corresponding changes in mRNA levels of FPS1, but rather can be related to the differential expression of genes involved in membrane protein secretion and yeast cellular physiology.
Collapse
Affiliation(s)
- Nicklas Bonander
- Department of Cell and Molecular Biology/Microbiology, Göteborg University, Sweden
| | | | | | | | | | | | | |
Collapse
|
24
|
Sørensen HP, Mortensen KK. Advanced genetic strategies for recombinant protein expression in Escherichia coli. J Biotechnol 2005; 115:113-28. [PMID: 15607230 DOI: 10.1016/j.jbiotec.2004.08.004] [Citation(s) in RCA: 593] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Revised: 08/26/2004] [Accepted: 08/30/2004] [Indexed: 11/15/2022]
Abstract
Preparations enriched by a specific protein are rarely easily obtained from natural host cells. Hence, recombinant protein production is frequently the sole applicable procedure. The ribosomal machinery, located in the cytoplasm is an outstanding catalyst of recombinant protein biosynthesis. Escherichia coli facilitates protein expression by its relative simplicity, its inexpensive and fast high-density cultivation, the well-known genetics and the large number of compatible tools available for biotechnology. Especially the variety of available plasmids, recombinant fusion partners and mutant strains have advanced the possibilities with E. coli. Although often simple for soluble proteins, major obstacles are encountered in the expression of many heterologous proteins and proteins lacking relevant interaction partners in the E. coli cytoplasm. Here we review the current most important strategies for recombinant expression in E. coli. Issues addressed include expression systems in general, selection of host strain, mRNA stability, codon bias, inclusion body formation and prevention, fusion protein technology and site-specific proteolysis, compartment directed secretion and finally co-overexpression technology. The macromolecular background for a variety of obstacles and genetic state-of-the-art solutions are presented.
Collapse
Affiliation(s)
- Hans Peter Sørensen
- Laboratory of BioDesign, Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10 C, DK-8000 Aarhus C, Denmark
| | | |
Collapse
|
25
|
Butt TR, Edavettal SC, Hall JP, Mattern MR. SUMO fusion technology for difficult-to-express proteins. Protein Expr Purif 2005; 43:1-9. [PMID: 16084395 PMCID: PMC7129290 DOI: 10.1016/j.pep.2005.03.016] [Citation(s) in RCA: 336] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 03/14/2005] [Accepted: 03/16/2005] [Indexed: 10/27/2022]
Abstract
The demands of structural and functional genomics for large quantities of soluble, properly folded proteins in heterologous hosts have been aided by advancements in the field of protein production and purification. Escherichia coli, the preferred host for recombinant protein expression, presents many challenges which must be surmounted in order to over-express heterologous proteins. These challenges include the proteolytic degradation of target proteins, protein misfolding, poor solubility, and the necessity for good purification methodologies. Gene fusion technologies have been able to improve heterologous expression by overcoming many of these challenges. The ability of gene fusions to improve expression, solubility, purification, and decrease proteolytic degradation will be discussed in this review. The main disadvantage, cleaving the protein fusion, will also be addressed. Focus will be given to the newly described SUMO fusion system and the improvements that this technology has advanced over traditional gene fusion systems.
Collapse
Affiliation(s)
- Tauseef R Butt
- LifeSensors, Inc., 271 Great Valley Parkway, Malvern, PA 19355, USA.
| | | | | | | |
Collapse
|
26
|
Sørensen HP, Mortensen KK. Soluble expression of recombinant proteins in the cytoplasm of Escherichia coli. Microb Cell Fact 2005; 4:1. [PMID: 15629064 PMCID: PMC544838 DOI: 10.1186/1475-2859-4-1] [Citation(s) in RCA: 473] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 01/04/2005] [Indexed: 11/10/2022] Open
Abstract
Pure, soluble and functional proteins are of high demand in modern biotechnology. Natural protein sources rarely meet the requirements for quantity, ease of isolation or price and hence recombinant technology is often the method of choice. Recombinant cell factories are constantly employed for the production of protein preparations bound for downstream purification and processing. Eschericia coli is a frequently used host, since it facilitates protein expression by its relative simplicity, its inexpensive and fast high density cultivation, the well known genetics and the large number of compatible molecular tools available. In spite of all these qualities, expression of recombinant proteins with E. coli as the host often results in insoluble and/or nonfunctional proteins. Here we review new approaches to overcome these obstacles by strategies that focus on either controlled expression of target protein in an unmodified form or by applying modifications using expressivity and solubility tags.
Collapse
Affiliation(s)
| | - Kim Kusk Mortensen
- Laboratory of BioDesign, Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| |
Collapse
|