1
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Komatsu S, Ohno H, Saito H. Target-dependent RNA polymerase as universal platform for gene expression control in response to intracellular molecules. Nat Commun 2023; 14:7256. [PMID: 37978180 PMCID: PMC10656481 DOI: 10.1038/s41467-023-42802-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/23/2023] [Indexed: 11/19/2023] Open
Abstract
Controlling gene expression in response to specific molecules is an essential technique for regulating cellular functions. However, current platforms with transcription and translation regulators have a limited number of detectable molecules to induce gene expression. Here to address these issues, we present a Target-dependent RNA polymerase (TdRNAP) that can induce RNA transcription in response to the intracellular target specifically recognized by single antibody. By substituting the fused antibody, we demonstrate that TdRNAPs respond to a wide variety of molecules, including peptides, proteins, RNA, and small molecules, and produce desired transcripts in human cells. Furthermore, we show that multiple TdRNAPs can construct orthogonal and multilayer genetic circuits. Finally, we apply TdRNAP to achieve cell-specific genome editing that is autonomously triggered by detecting the target gene product. TdRNAP can expand the molecular variety for controlling gene expression and provide the genetic toolbox for bioengineering and future therapeutic applications.
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Affiliation(s)
- Shodai Komatsu
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
- Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hirohisa Ohno
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Hirohide Saito
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
- Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
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2
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Robinson MP, Jung J, Lopez-Barbosa N, Chang M, Li M, Jaroentomeechai T, Cox EC, Zheng X, Berkmen M, DeLisa MP. Isolation of full-length IgG antibodies from combinatorial libraries expressed in the cytoplasm of Escherichia coli. Nat Commun 2023; 14:3514. [PMID: 37316535 PMCID: PMC10267130 DOI: 10.1038/s41467-023-39178-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/01/2023] [Indexed: 06/16/2023] Open
Abstract
Here we describe a facile and robust genetic selection for isolating full-length IgG antibodies from combinatorial libraries expressed in the cytoplasm of redox-engineered Escherichia coli cells. The method is based on the transport of a bifunctional substrate comprised of an antigen fused to chloramphenicol acetyltransferase, which allows positive selection of bacterial cells co-expressing cytoplasmic IgGs called cyclonals that specifically capture the chimeric antigen and sequester the antibiotic resistance marker in the cytoplasm. The utility of this approach is first demonstrated by isolating affinity-matured cyclonal variants that specifically bind their cognate antigen, the leucine zipper domain of a yeast transcriptional activator, with subnanomolar affinities, which represent a ~20-fold improvement over the parental IgG. We then use the genetic assay to discover antigen-specific cyclonals from a naïve human antibody repertoire, leading to the identification of lead IgG candidates with affinity and specificity for an influenza hemagglutinin-derived peptide antigen.
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Affiliation(s)
- Michael-Paul Robinson
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Jinjoo Jung
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Natalia Lopez-Barbosa
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Matthew Chang
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Mingji Li
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Thapakorn Jaroentomeechai
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Emily C Cox
- Biomedical and Biological Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Xiaolu Zheng
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Mehmet Berkmen
- New England Biolabs, 240 County Road, Ipswich, MA, 01938, USA
| | - Matthew P DeLisa
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA.
- Biomedical and Biological Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
- Cornell Institute of Biotechnology, Cornell University, Ithaca, NY, 14853, USA.
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3
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Taw MN, Li M, Kim D, Rocco MA, Waraho-Zhmayev D, DeLisa MP. Engineering a Supersecreting Strain of Escherichia coli by Directed Coevolution of the Multiprotein Tat Translocation Machinery. ACS Synth Biol 2021; 10:2947-2958. [PMID: 34757717 DOI: 10.1021/acssynbio.1c00183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Escherichia coli remains one of the preferred hosts for biotechnological protein production due to its robust growth in culture and ease of genetic manipulation. It is often desirable to export recombinant proteins into the periplasmic space for reasons related to proper disulfide bond formation, prevention of aggregation and proteolytic degradation, and ease of purification. One such system for expressing heterologous secreted proteins is the twin-arginine translocation (Tat) pathway, which has the unique advantage of delivering correctly folded proteins into the periplasm. However, transit times for proteins through the Tat translocase, comprised of the TatABC proteins, are much longer than for passage through the SecYEG pore, the translocase associated with the more widely utilized Sec pathway. To date, a high protein flux through the Tat pathway has yet to be demonstrated. To address this shortcoming, we employed a directed coevolution strategy to isolate mutant Tat translocases for their ability to deliver higher quantities of heterologous proteins into the periplasm. Three supersecreting translocases were selected that each exported a panel of recombinant proteins at levels that were significantly greater than those observed for wild-type TatABC or SecYEG translocases. Interestingly, all three of the evolved Tat translocases exhibited quality control suppression, suggesting that increased translocation flux was gained by relaxation of substrate proofreading. Overall, our discovery of more efficient translocase variants paves the way for the use of the Tat system as a powerful complement to the Sec pathway for secreted production of both commodity and high value-added proteins.
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Affiliation(s)
- May N. Taw
- Department of Microbiology, Cornell University, Ithaca, New York 14853, United States
| | - Mingji Li
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853, United States
| | - Daniel Kim
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853, United States
| | - Mark A. Rocco
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853, United States
| | - Dujduan Waraho-Zhmayev
- Biological Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand
| | - Matthew P. DeLisa
- Department of Microbiology, Cornell University, Ithaca, New York 14853, United States
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853, United States
- Cornell Institute of Biotechnology, Cornell University, 130 Biotechnology Building, Ithaca, New York 14853, United States
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4
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Ren C, Wen X, Mencius J, Quan S. Selection and screening strategies in directed evolution to improve protein stability. BIORESOUR BIOPROCESS 2019. [DOI: 10.1186/s40643-019-0288-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractProtein stability is not only fundamental for experimental, industrial, and therapeutic applications, but is also the baseline for evolving novel protein functions. For decades, stability engineering armed with directed evolution has continued its rapid development and inevitably poses challenges. Generally, in directed evolution, establishing a reliable link between a genotype and any interpretable phenotype is more challenging than diversifying genetic libraries. Consequently, we set forth in a small picture to emphasize the screening or selection techniques in protein stability-directed evolution to secure the link. For a more systematic review, two main branches of these techniques, namely cellular or cell-free display and stability biosensors, are expounded with informative examples.
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5
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Meksiriporn B, Ludwicki MB, Stephens EA, Jiang A, Lee HC, Waraho-Zhmayev D, Kummer L, Brandl F, Plückthun A, DeLisa MP. A survival selection strategy for engineering synthetic binding proteins that specifically recognize post-translationally phosphorylated proteins. Nat Commun 2019; 10:1830. [PMID: 31015433 PMCID: PMC6478843 DOI: 10.1038/s41467-019-09854-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 03/28/2019] [Indexed: 02/06/2023] Open
Abstract
There is an urgent need for affinity reagents that target phospho-modified sites on individual proteins; however, generating such reagents remains a significant challenge. Here, we describe a genetic selection strategy for routine laboratory isolation of phospho-specific designed ankyrin repeat proteins (DARPins) by linking in vivo affinity capture of a phosphorylated target protein with antibiotic resistance of Escherichia coli cells. The assay is validated using an existing panel of DARPins that selectively bind the nonphosphorylated (inactive) form of extracellular signal-regulated kinase 2 (ERK2) or its doubly phosphorylated (active) form (pERK2). We then use the selection to affinity-mature a phospho-specific DARPin without compromising its selectivity for pERK2 over ERK2 and to reprogram the substrate specificity of the same DARPin towards non-cognate ERK2. Collectively, these results establish our genetic selection as a useful and potentially generalizable protein engineering tool for studying phospho-specific binding proteins and customizing their affinity and selectivity. Protein phosphorylation helps to control many important cellular activities. Here the authors describe a genetic selection strategy to isolate designed ankyrin repeat proteins that bind specifically to phosphomodified targets.
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Affiliation(s)
- Bunyarit Meksiriporn
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Morgan B Ludwicki
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Erin A Stephens
- Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Allen Jiang
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Hyeon-Cheol Lee
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Dujduan Waraho-Zhmayev
- Biological Engineering Program, Faculty of Engineering, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand
| | - Lutz Kummer
- Department of Biochemistry, University of Zürich, 8057, Zürich, Switzerland
| | - Fabian Brandl
- Department of Biochemistry, University of Zürich, 8057, Zürich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zürich, 8057, Zürich, Switzerland
| | - Matthew P DeLisa
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA. .,Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA. .,Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY, 14853, USA.
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6
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Brechun KE, Arndt KM, Woolley GA. Selection of Protein-Protein Interactions of Desired Affinities with a Bandpass Circuit. J Mol Biol 2019; 431:391-400. [PMID: 30448232 DOI: 10.1016/j.jmb.2018.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 11/17/2022]
Abstract
We have developed a genetic circuit in Escherichia coli that can be used to select for protein-protein interactions of different strengths by changing antibiotic concentrations in the media. The genetic circuit links protein-protein interaction strength to β-lactamase activity while simultaneously imposing tuneable positive and negative selection pressure for β-lactamase activity. Cells only survive if they express interacting proteins with affinities that fall within set high- and low-pass thresholds; i.e. the circuit therefore acts as a bandpass filter for protein-protein interactions. We show that the circuit can be used to recover protein-protein interactions of desired affinity from a mixed population with a range of affinities. The circuit can also be used to select for inhibitors of protein-protein interactions of defined strength.
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Affiliation(s)
- Katherine E Brechun
- Department of Chemistry, University of Toronto, Toronto, Canada; Molecular Biotechnology, University of Potsdam, Potsdam, Germany
| | - Katja M Arndt
- Molecular Biotechnology, University of Potsdam, Potsdam, Germany.
| | - G Andrew Woolley
- Department of Chemistry, University of Toronto, Toronto, Canada.
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7
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Computational affinity maturation of camelid single-domain intrabodies against the nonamyloid component of alpha-synuclein. Sci Rep 2018; 8:17611. [PMID: 30514850 PMCID: PMC6279780 DOI: 10.1038/s41598-018-35464-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 10/26/2018] [Indexed: 12/21/2022] Open
Abstract
Improving the affinity of protein-protein interactions is a challenging problem that is particularly important in the development of antibodies for diagnostic and clinical use. Here, we used structure-based computational methods to optimize the binding affinity of VHNAC1, a single-domain intracellular antibody (intrabody) from the camelid family that was selected for its specific binding to the nonamyloid component (NAC) of human α-synuclein (α-syn), a natively disordered protein, implicated in the pathogenesis of Parkinson's disease (PD) and related neurological disorders. Specifically, we performed ab initio modeling that revealed several possible modes of VHNAC1 binding to the NAC region of α-syn as well as mutations that potentially enhance the affinity between these interacting proteins. While our initial design strategy did not lead to improved affinity, it ultimately guided us towards a model that aligned more closely with experimental observations, revealing a key residue on the paratope and the participation of H4 loop residues in binding, as well as confirming the importance of electrostatic interactions. The binding activity of the best intrabody mutant, which involved just a single amino acid mutation compared to parental VHNAC1, was significantly enhanced primarily through a large increase in association rate. Our results indicate that structure-based computational design can be used to successfully improve the affinity of antibodies against natively disordered and weakly immunogenic antigens such as α-syn, even in cases such as ours where crystal structures are unavailable.
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8
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Sachsenhauser V, Bardwell JC. Directed evolution to improve protein folding in vivo. Curr Opin Struct Biol 2018; 48:117-123. [PMID: 29278775 PMCID: PMC5880552 DOI: 10.1016/j.sbi.2017.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/13/2017] [Indexed: 02/06/2023]
Abstract
Recently, several innovative approaches have been developed that allow one to directly screen or select for improved protein folding in the cellular context. These methods have the potential of not just leading to a better understanding of the in vivo folding process, they may also allow for improved production of proteins of biotechnological interest.
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Affiliation(s)
- Veronika Sachsenhauser
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University, Ann Arbor, MI 48109, USA
| | - James Ca Bardwell
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, 830 N. University, Ann Arbor, MI 48109, USA.
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9
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Boonyalekha P, Meechai A, Tayapiwatana C, Kitidee K, Waraho-Zhmayev D. Design and construction of a synthetic E. coli protease inhibitor detecting biomachine. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:3580-3583. [PMID: 29060672 DOI: 10.1109/embc.2017.8037631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Protease inhibitors (PIs) have been used to treat various types of symptoms or diseases. However, current PIs block the protease activity by targeting the protease active site which has been shown to be sensitive to the off-target effect due to crossreactivity with protease homologues. An alternative approach to inhibiting protease activity is to target the substrate, specifically by blocking the substrate cleavage site. We propose to employ synthetic biology approach to create a synthetic E. coli to be used as a protease inhibitor detecting biomachine that can effectively isolate intrabodies, a new generation of protease inhibitor drug. The in vivo selection system, comprised of three biological devices, i.e., protease activity detector, protease generator and protease blocking devices, is based on the ability to transport folded protein of the E. coli twin-arginine translocation (Tat) pathway and antibiotic resistance of TEM-1 β-lactamase (Bla) using as reporter protein. By linking protease degradation to antibiotic resistance, we can isolate the suitable intrabodies simply by plating cells containing appropriate devices on solid agar containing β-lactam ring antibiotics. As a proof of concept, we applied a previously isolated HIV-1 p17 intrabody (scFvp17) that binds to the C-terminus of HIV-1 matrix protein (p17) to our synthetic E. coli. This work demonstrated that binding of scFvp17 to its epitope on p17 can physically interfere with HIV-1 protease activity and inhibit proteolytic cleavage at the p17Δp24 cleavage site when expressed in the designed format. The device was optimized by varying plating conditions such as incubation temperatures, induction levels, and Carbenicillin concentrations which was used as selection pressure. The feasibility of this assay has opened the door to protease inhibitor selection which can be used for various applications such as optimization of the current protease inhibitors and selection of new ones.
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10
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An Intrabody Drug (rAAV6-INT41) Reduces the Binding of N-Terminal Huntingtin Fragment(s) to DNA to Basal Levels in PC12 Cells and Delays Cognitive Loss in the R6/2 Animal Model. JOURNAL OF NEURODEGENERATIVE DISEASES 2016; 2016:7120753. [PMID: 27595037 PMCID: PMC4995342 DOI: 10.1155/2016/7120753] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/27/2016] [Indexed: 01/01/2023]
Abstract
Huntington's disease (HD) is a fatal progressive disease linked to expansion of glutamine repeats in the huntingtin protein and characterized by the progressive loss of cognitive and motor function. We show that expression of a mutant human huntingtin exon-1-GFP fusion construct results in nonspecific gene dysregulation that is significantly reduced by 50% due to coexpression of INT41, an intrabody specific for the proline-rich region of the huntingtin protein. Using stable PC12 cell lines expressing either inducible human mutant huntingtin (mHtt, Q73) or normal huntingtin (nHtt, Q23), we investigated the effect of rAAV6-INT41, an adeno-associated virus vector with the INT41 coding sequence, on the subcellular distribution of Htt. Compartmental fractionation 8 days after induction of Htt showed a 6-fold increased association of a dominate N-terminal mHtt fragment with DNA compared to N-terminal nHtt. Transduction with rAAV6-INT41 reduced DNA binding of N-terminal mHtt 6.5-fold in the nucleus and reduced nuclear translocation of the detected fragments. Subsequently, when rAAV6-INT41 is delivered to the striatum in the R6/2 mouse model, treated female mice exhibited executive function statistically indistinguishable from wild type, accompanied by reductions in Htt aggregates in the striatum, suggesting that rAAV6-INT41 is promising as a gene therapy for Huntington's disease.
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11
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Marschall ALJ, Dübel S, Böldicke T. Specific in vivo knockdown of protein function by intrabodies. MAbs 2015; 7:1010-35. [PMID: 26252565 PMCID: PMC4966517 DOI: 10.1080/19420862.2015.1076601] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 07/19/2015] [Accepted: 07/20/2015] [Indexed: 01/02/2023] Open
Abstract
Intracellular antibodies (intrabodies) are recombinant antibody fragments that bind to target proteins expressed inside of the same living cell producing the antibodies. The molecules are commonly used to study the function of the target proteins (i.e., their antigens). The intrabody technology is an attractive alternative to the generation of gene-targeted knockout animals, and complements knockdown techniques such as RNAi, miRNA and small molecule inhibitors, by-passing various limitations and disadvantages of these methods. The advantages of intrabodies include very high specificity for the target, the possibility to knock down several protein isoforms by one intrabody and targeting of specific splice variants or even post-translational modifications. Different types of intrabodies must be designed to target proteins at different locations, typically either in the cytoplasm, in the nucleus or in the endoplasmic reticulum (ER). Most straightforward is the use of intrabodies retained in the ER (ER intrabodies) to knock down the function of proteins passing the ER, which disturbs the function of members of the membrane or plasma proteomes. More effort is needed to functionally knock down cytoplasmic or nuclear proteins because in this case antibodies need to provide an inhibitory effect and must be able to fold in the reducing milieu of the cytoplasm. In this review, we present a broad overview of intrabody technology, as well as applications both of ER and cytoplasmic intrabodies, which have yielded valuable insights in the biology of many targets relevant for drug development, including α-synuclein, TAU, BCR-ABL, ErbB-2, EGFR, HIV gp120, CCR5, IL-2, IL-6, β-amyloid protein and p75NTR. Strategies for the generation of intrabodies and various designs of their applications are also reviewed.
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Affiliation(s)
- Andrea LJ Marschall
- Technische Universität Braunschweig, Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany
| | - Stefan Dübel
- Technische Universität Braunschweig, Institute of Biochemistry, Biotechnology and Bioinformatics; Braunschweig, Germany
| | - Thomas Böldicke
- Helmholtz Centre for Infection Research, Recombinant Protein Expression/Intrabody Unit, Helmholtz Centre for Infection Research; Braunschweig, Germany
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12
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Beyond the cytoplasm of Escherichia coli: localizing recombinant proteins where you want them. Methods Mol Biol 2015; 1258:79-97. [PMID: 25447860 DOI: 10.1007/978-1-4939-2205-5_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Recombinant protein expression in Escherichia coli represents a cornerstone of the biotechnology enterprise. While cytoplasmic expression in this host has received the most attention, achieving substantial yields of correctly folded proteins in this compartment can sometimes be met with difficulties. These issues can often be overcome by targeting protein expression to extracytoplasmic compartments (e.g., membrane, periplasm) or to the culture medium. This chapter discusses various strategies for exporting proteins out of the cytoplasm as well as tools for monitoring and optimizing these different export mechanisms.
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13
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An engineered genetic selection for ternary protein complexes inspired by a natural three-component hitchhiker mechanism. Sci Rep 2014; 4:7570. [PMID: 25531212 PMCID: PMC4273604 DOI: 10.1038/srep07570] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/02/2014] [Indexed: 12/29/2022] Open
Abstract
The bacterial twin-arginine translocation (Tat) pathway is well known to translocate correctly folded monomeric and dimeric proteins across the tightly sealed cytoplasmic membrane. We identified a naturally occurring heterotrimer, the Escherichia coli aldehyde oxidoreductase PaoABC, that is co-translocated by the Tat translocase according to a ternary “hitchhiker” mechanism. Specifically, the PaoB and PaoC subunits, each devoid of export signals, are escorted to the periplasm in a piggyback fashion by the Tat signal peptide-containing subunit PaoA. Moreover, export of PaoA was blocked when either PaoB or PaoC was absent, revealing a surprising interdependence for export that is not seen for classical secretory proteins. Inspired by this observation, we created a bacterial three-hybrid selection system that links the formation of ternary protein complexes with antibiotic resistance. As proof-of-concept, a bispecific antibody was employed as an adaptor that physically crosslinked one antigen fused to a Tat export signal with a second antigen fused to TEM-1 β-lactamase (Bla). The resulting non-covalent heterotrimer was exported in a Tat-dependent manner, delivering Bla to the periplasm where it hydrolyzed β-lactam antibiotics. Collectively, these results highlight the remarkable flexibility of the Tat system and its potential for studying and engineering ternary protein interactions in living bacteria.
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14
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Waraho-Zhmayev D, Meksiriporn B, Portnoff AD, DeLisa MP. Optimizing recombinant antibodies for intracellular function using hitchhiker-mediated survival selection. Protein Eng Des Sel 2014; 27:351-8. [PMID: 25225416 DOI: 10.1093/protein/gzu038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The 'hitchhiker' mechanism of the bacterial twin-arginine translocation pathway has previously been adapted as a genetic selection for detecting pairwise protein interactions in the cytoplasm of living Escherichia coli cells. Here, we extended this method, called FLI-TRAP, for rapid isolation of intracellular antibodies (intrabodies) in the single-chain Fv format that possess superior traits simply by demanding bacterial growth on high concentrations of antibiotic. Following just a single round of survival-based enrichment using FLI-TRAP, variants of an intrabody against the dimerization domain of the yeast Gcn4p transcription factor were isolated having significantly greater intracellular stability that translated to yield enhancements of >10-fold. Likewise, an intrabody specific for the non-amyloid component region of α-synuclein was isolated that has ~8-fold improved antigen-binding affinity. Collectively, our results illustrate the potential of the FLI-TRAP method for intracellular stabilization and affinity maturation of intrabodies, all without the need for purification or immobilization of the antigen.
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Affiliation(s)
- Dujduan Waraho-Zhmayev
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA Biological Engineering Program, Faculty of Engineering, King Mongkut's University of Technology Thonburi, 126 Pracha-utid Road, Bangmod, Toongkru, Bangkok 10140, Thailand
| | | | - Alyse D Portnoff
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Matthew P DeLisa
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
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15
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Kükenshöner T, Wohlwend D, Niemöller C, Dondapati P, Speck J, Adeniran AV, Nieth A, Gerhardt S, Einsle O, Müller KM, Arndt KM. Improving coiled coil stability while maintaining specificity by a bacterial hitchhiker selection system. J Struct Biol 2014; 186:335-48. [PMID: 24631970 DOI: 10.1016/j.jsb.2014.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/28/2014] [Accepted: 03/01/2014] [Indexed: 12/12/2022]
Abstract
The design and selection of peptides targeting cellular proteins is challenging and often yields candidates with undesired properties. Therefore we deployed a new selection system based on the twin-arginine translocase (TAT) pathway of Escherichia coli, named hitchhiker translocation (HiT) selection. A pool of α-helix encoding sequences was designed and selected for interference with the coiled coil domain (CC) of a melanoma-associated basic-helix-loop-helix-leucine-zipper (bHLHLZ) protein, the microphthalmia associated transcription factor (MITF). One predominant sequence (iM10) was enriched during selection and showed remarkable protease resistance, high solubility and thermal stability while maintaining its specificity. Furthermore, it exhibited nanomolar range affinity towards the target peptide. A mutation screen indicated that target-binding helices of increased homodimer stability and improved expression rates were preferred in the selection process. The crystal structure of the iM10/MITF-CC heterodimer (2.1Å) provided important structural insights and validated our design predictions. Importantly, iM10 did not only bind to the MITF coiled coil, but also to the markedly more stable HLHLZ domain of MITF. Characterizing the selected variants of the semi-rational library demonstrated the potential of the innovative bacterial selection approach.
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Affiliation(s)
- Tim Kükenshöner
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany
| | - Daniel Wohlwend
- Institute for Biochemistry, University of Freiburg, Freiburg im Breisgau, Germany
| | - Christoph Niemöller
- Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany
| | - Padmarupa Dondapati
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany
| | - Janina Speck
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany
| | - Adebola V Adeniran
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany
| | - Anita Nieth
- Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany; Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg im Breisgau, Germany; Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Stefan Gerhardt
- Institute for Biochemistry, University of Freiburg, Freiburg im Breisgau, Germany
| | - Oliver Einsle
- Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg im Breisgau, Germany; Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg im Breisgau, Germany; Institute for Biochemistry, University of Freiburg, Freiburg im Breisgau, Germany
| | - Kristian M Müller
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany; Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, Germany
| | - Katja M Arndt
- Molecular Biotechnology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany; Institute for Biology III, University of Freiburg, Freiburg im Breisgau, Germany; Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg im Breisgau, Germany; Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg im Breisgau, Germany.
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16
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O'Brien SP, DeLisa MP. Split-Cre recombinase effectively monitors protein-protein interactions in living bacteria. Biotechnol J 2014; 9:355-61. [DOI: 10.1002/biot.201300462] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/13/2013] [Accepted: 12/31/2013] [Indexed: 01/15/2023]
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17
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Portnoff AD, Stephens EA, Varner JD, DeLisa MP. Ubiquibodies, synthetic E3 ubiquitin ligases endowed with unnatural substrate specificity for targeted protein silencing. J Biol Chem 2014; 289:7844-55. [PMID: 24474696 DOI: 10.1074/jbc.m113.544825] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The ubiquitin-proteasome pathway (UPP) is the main route of protein degradation in eukaryotic cells and is a common mechanism through which numerous cellular pathways are regulated. To date, several reverse genetics techniques have been reported that harness the power of the UPP for selectively reducing the levels of otherwise stable proteins. However, each of these approaches has been narrowly developed for a single substrate and cannot be easily extended to other protein substrates of interest. To address this shortcoming, we created a generalizable protein knock-out method by engineering protein chimeras called "ubiquibodies" that combine the activity of E3 ubiquitin ligases with designer binding proteins to steer virtually any protein to the UPP for degradation. Specifically, we reprogrammed the substrate specificity of a modular human E3 ubiquitin ligase called CHIP (carboxyl terminus of Hsc70-interacting protein) by replacing its natural substrate-binding domain with a single-chain Fv (scFv) intrabody or a fibronectin type III domain monobody that target their respective antigens with high specificity and affinity. Engineered ubiquibodies reliably transferred ubiquitin to surface exposed lysines on target proteins and even catalyzed the formation of biologically relevant polyubiquitin chains. Following ectopic expression of ubiquibodies in mammalian cells, specific and systematic depletion of desired target proteins was achieved, whereas the levels of a natural substrate of CHIP were unaffected. Taken together, engineered ubiquibodies offer a simple, reproducible, and customizable means for directly removing specific cellular proteins through accelerated proteolysis.
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18
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Azuma Y, Kükenshöner T, Ma G, Yasunaga JI, Imanishi M, Tanaka G, Nakase I, Maruno T, Kobayashi Y, Arndt KM, Matsuoka M, Futaki S. Controlling leucine-zipper partner recognition in cells through modification of a–g interactions. Chem Commun (Camb) 2014; 50:6364-7. [DOI: 10.1039/c4cc00555d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By focusing on the a–g interactions, successful design and selection were accomplished to obtain a leucine-zipper segment that discriminates the appropriate partner.
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Affiliation(s)
- Yusuke Azuma
- Institute for Chemical Research
- Kyoto University
- Uji, Japan
| | - Tim Kükenshöner
- Institute for Biochemistry and Biology
- University of Potsdam
- 14476 Potsdam-Golm, Germany
| | - Guangyong Ma
- Institute for Virus Research
- Kyoto University
- Sakyo-ku, Japan
| | | | - Miki Imanishi
- Institute for Chemical Research
- Kyoto University
- Uji, Japan
| | - Gen Tanaka
- Institute for Chemical Research
- Kyoto University
- Uji, Japan
| | - Ikuhiko Nakase
- Institute for Chemical Research
- Kyoto University
- Uji, Japan
| | | | - Yuji Kobayashi
- Graduate School of Engineering
- Osaka University
- Suita, Japan
| | - Katja M. Arndt
- Institute for Biochemistry and Biology
- University of Potsdam
- 14476 Potsdam-Golm, Germany
| | - Masao Matsuoka
- Institute for Virus Research
- Kyoto University
- Sakyo-ku, Japan
| | - Shiroh Futaki
- Institute for Chemical Research
- Kyoto University
- Uji, Japan
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19
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Wang Y, Yang W, Wang Q, Qu J, Zhang Y. Presenting a foreign antigen on live attenuated Edwardsiella tarda using twin-arginine translocation signal peptide as a multivalent vaccine. J Biotechnol 2013; 168:710-7. [DOI: 10.1016/j.jbiotec.2013.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 08/10/2013] [Accepted: 08/14/2013] [Indexed: 02/05/2023]
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20
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Waraho-Zhmayev D, Gkogka L, Yu TY, DeLisa MP. A microbial sensor for discovering structural probes of protein misfolding and aggregation. Prion 2013; 7:151-6. [PMID: 23357829 DOI: 10.4161/pri.23328] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In all cell types, protein homeostasis, or "proteostasis," is maintained by sophisticated quality control networks that regulate protein synthesis, folding, trafficking, aggregation, disaggregation, and degradation. In one notable example, Escherichia coli employ a proteostasis system that determines whether substrates of the twin-arginine translocation (Tat) pathway are correctly folded and thus suitable for transport across the tightly sealed cytoplasmic membrane. Herein, we review growing evidence that the Tat translocase itself discriminates folded proteins from those that are misfolded and/or aggregated, preferentially exporting only the former. Genetic suppressors that inactivate this mechanism have recently been isolated and provide direct evidence for the participation of the Tat translocase in structural proofreading of its protein substrates. We also discuss how this discriminatory "folding sensor" has been exploited for the discovery of structural probes (e.g., sequence mutations, pharmacologic chaperones, intracellular antibodies) that modulate the folding and solubility of virtually any protein-of-interest, including those associated with aggregation diseases (e.g., α-synuclein, amyloid-β protein). Taken together, these studies highlight the utility of engineered bacteria for rapidly and inexpensively uncovering potent anti-aggregation factors.
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Speck J, Räuber C, Kükenshöner T, Niemöller C, Mueller KJ, Schleberger P, Dondapati P, Hecky J, Arndt KM, Müller KM. TAT hitchhiker selection expanded to folding helpers, multimeric interactions and combinations with protein fragment complementation. Protein Eng Des Sel 2012; 26:225-42. [PMID: 23223941 DOI: 10.1093/protein/gzs098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Janina Speck
- Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany
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22
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Diversity in genetic in vivo methods for protein-protein interaction studies: from the yeast two-hybrid system to the mammalian split-luciferase system. Microbiol Mol Biol Rev 2012; 76:331-82. [PMID: 22688816 DOI: 10.1128/mmbr.05021-11] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The yeast two-hybrid system pioneered the field of in vivo protein-protein interaction methods and undisputedly gave rise to a palette of ingenious techniques that are constantly pushing further the limits of the original method. Sensitivity and selectivity have improved because of various technical tricks and experimental designs. Here we present an exhaustive overview of the genetic approaches available to study in vivo binary protein interactions, based on two-hybrid and protein fragment complementation assays. These methods have been engineered and employed successfully in microorganisms such as Saccharomyces cerevisiae and Escherichia coli, but also in higher eukaryotes. From single binary pairwise interactions to whole-genome interactome mapping, the self-reassembly concept has been employed widely. Innovative studies report the use of proteins such as ubiquitin, dihydrofolate reductase, and adenylate cyclase as reconstituted reporters. Protein fragment complementation assays have extended the possibilities in protein-protein interaction studies, with technologies that enable spatial and temporal analyses of protein complexes. In addition, one-hybrid and three-hybrid systems have broadened the types of interactions that can be studied and the findings that can be obtained. Applications of these technologies are discussed, together with the advantages and limitations of the available assays.
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23
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Waraho D, DeLisa MP. Identifying and optimizing intracellular protein-protein interactions using bacterial genetic selection. Methods Mol Biol 2012; 813:125-143. [PMID: 22083739 DOI: 10.1007/978-1-61779-412-4_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Protein-protein interactions are crucial for the vast majority of biological processes. To fully understand these processes therefore requires methods for identifying protein interactions within the complex cellular environment. To isolate interacting proteins, we have developed a simple and reliable genetic selection by exploiting the inbuilt "hitchhiker" mechanism of the Escherichia coli twin-arginine translocation (Tat) pathway. This method is based on the unique ability of the Tat system to efficiently co-localize noncovalent complexes of two folded polypeptides to the periplasmic space of E. coli. The genetic selection is comprised of two engineered fusion proteins: an N-terminal Tat signal peptide fused to the protein of interest, and the known or putative partner protein fused to mature TEM-1 β-lactamase. The efficiency with which co-localized β-lactamase chimeras are exported in the periplasm, and thus confer ampicillin resistance to cells, is directly linked to the relative binding affinity of the protein-ligand system. Thus, ampicillin resistance can be used as a convenient readout for identifying and optimizing protein interactions in E. coli. Furthermore, because Tat substrates must be correctly folded for export, our method favors the identification of soluble, non-aggregating, protease-resistant protein pairs. Overall, we anticipate that this new selection tool will be useful for discovering and engineering protein drugs, protein complexes for structural biology, factors that inhibit PPIs, and components for synthetic biology.
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Affiliation(s)
- Dujduan Waraho
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA
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Karlsson AJ, Lim HK, Xu H, Rocco MA, Bratkowski MA, Ke A, DeLisa MP. Engineering antibody fitness and function using membrane-anchored display of correctly folded proteins. J Mol Biol 2011; 416:94-107. [PMID: 22197376 DOI: 10.1016/j.jmb.2011.12.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/06/2011] [Accepted: 12/09/2011] [Indexed: 10/14/2022]
Abstract
A hallmark of the bacterial twin-arginine translocation (Tat) pathway is its ability to export folded proteins. Here, we discovered that overexpressed Tat substrate proteins form two distinct, long-lived translocation intermediates that are readily detected by immunolabeling methods. Formation of the early translocation intermediate Ti-1, which exposes the N- and C-termini to the cytoplasm, did not require an intact Tat translocase, a functional Tat signal peptide, or a correctly folded substrate. In contrast, formation of the later translocation intermediate, Ti-2, which exhibits a bitopic topology with the N-terminus in the cytoplasm and C-terminus in the periplasm, was much more particular, requiring an intact translocase, a functional signal peptide, and a correctly folded substrate protein. The ability to directly detect Ti-2 intermediates was subsequently exploited for a new protein engineering technology called MAD-TRAP (membrane-anchored display for Tat-based recognition of associating proteins). Through the use of just two rounds of mutagenesis and screening with MAD-TRAP, the intracellular folding and antigen-binding activity of a human single-chain antibody fragment were simultaneously improved. This approach has several advantages for library screening, including the unique involvement of the Tat folding quality control mechanism that ensures only native-like proteins are displayed, thus eliminating poorly folded sequences from the screening process.
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Affiliation(s)
- Amy J Karlsson
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
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25
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Appraisal of translocation pathways for displaying ankyrin repeat protein on phage particles. Protein Expr Purif 2010; 74:156-61. [DOI: 10.1016/j.pep.2010.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 08/20/2010] [Accepted: 08/20/2010] [Indexed: 01/01/2023]
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26
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Lim HK, Mansell TJ, Linderman SW, Fisher AC, Dyson MR, DeLisa MP. Mining mammalian genomes for folding competent proteins using Tat-dependent genetic selection in Escherichia coli. Protein Sci 2010; 18:2537-49. [PMID: 19830686 DOI: 10.1002/pro.262] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recombinant expression of eukaryotic proteins in Escherichia coli is often limited by poor folding and solubility. To address this problem, we employed a recently developed genetic selection for protein folding and solubility based on the bacterial twin-arginine translocation (Tat) pathway to rapidly identify properly folded recombinant proteins or soluble protein domains of mammalian origin. The coding sequences for 29 different mammalian polypeptides were cloned as sandwich fusions between an N-terminal Tat export signal and a C-terminal selectable marker, namely beta-lactamase. Hence, expression of the selectable marker and survival on selective media was linked to Tat export of the target mammalian protein. Since the folding quality control feature of the Tat pathway prevents export of misfolded proteins, only correctly folded fusion proteins reached the periplasm and conferred cell survival. In general, the ability to confer growth was found to relate closely to the solubility profile and molecular weight of the protein, although other features such as number of contiguous hydrophobic amino acids and cysteine content may also be important. These results highlight the capacity of Tat selection to reveal the folding potential of mammalian proteins and protein domains without the need for structural or functional information about the target protein.
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Affiliation(s)
- Hyung-Kwon Lim
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
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27
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Kostecki JS, Li H, Turner RJ, DeLisa MP. Visualizing interactions along the Escherichia coli twin-arginine translocation pathway using protein fragment complementation. PLoS One 2010; 5:e9225. [PMID: 20169075 PMCID: PMC2821923 DOI: 10.1371/journal.pone.0009225] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Accepted: 01/18/2010] [Indexed: 11/23/2022] Open
Abstract
The twin-arginine translocation (Tat) pathway is well known for its ability to export fully folded substrate proteins out of the cytoplasm of Gram-negative and Gram-positive bacteria. Studies of this mechanism in Escherichia coli have identified numerous transient protein-protein interactions that guide export-competent proteins through the Tat pathway. To visualize these interactions, we have adapted bimolecular fluorescence complementation (BiFC) to detect protein-protein interactions along the Tat pathway of living cells. Fragments of the yellow fluorescent protein (YFP) were fused to soluble and transmembrane factors that participate in the translocation process including Tat substrates, Tat-specific proofreading chaperones and the integral membrane proteins TatABC that form the translocase. Fluorescence analysis of these YFP chimeras revealed a wide range of interactions such as the one between the Tat substrate dimethyl sulfoxide reductase (DmsA) and its dedicated proofreading chaperone DmsD. In addition, BiFC analysis illuminated homo- and hetero-oligomeric complexes of the TatA, TatB and TatC integral membrane proteins that were consistent with the current model of translocase assembly. In the case of TatBC assemblies, we provide the first evidence that these complexes are co-localized at the cell poles. Finally, we used this BiFC approach to capture interactions between the putative Tat receptor complex formed by TatBC and the DmsA substrate or its dedicated chaperone DmsD. Our results demonstrate that BiFC is a powerful approach for studying cytoplasmic and inner membrane interactions underlying bacterial secretory pathways.
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Affiliation(s)
- Jan S. Kostecki
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America
| | - Haiming Li
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Raymond J. Turner
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Matthew P. DeLisa
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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