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Khoury F, Su Z, Banta S. Rare Earth Element Binding and Recovery by a Beta Roll-Forming RTX Domain. Inorg Chem 2024; 63:13223-13230. [PMID: 38986039 DOI: 10.1021/acs.inorgchem.4c00420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
The Block V of the RTX domain of the adenylate cyclase protein from Bordetella pertussis is disordered, and upon binding eight calcium ions, it folds into a beta roll domain with a C-terminal capping group. Due to their similar ionic radii and coordination geometries, trivalent lanthanide ions have been used to probe and identify calcium-binding sites in many proteins. Here, we report using a FRET-based assay that the RTX domain can bind rare earth elements (REEs) with higher affinities than calcium. The apparent disassociation constants for lanthanide ions ranged from 20 to 75 μM, which are an order of magnitude higher than the affinity for calcium, with a higher selectivity toward heavy REEs over light REEs. Most proteins release bound ions at mildly acidic conditions (pH 5-6), and the high affinity REE-binding lanmodulin protein can bind 3-4 REE ions at pH as low as ∼2.5. Circular dichroism (CD) spectra of the RTX domain demonstrate pH-induced folding of the beta roll domain in the absence of ions, indicating that protonation of key amino acids enables structure formation in low pH solutions. The beta roll domain coordinates up to four ions in extreme pH conditions (pH < 1), as determined by equilibrium ultrafiltration experiments. Finally, to demonstrate a potential application of the RTX domain, REE ions (Nd3+ and Dy3+) were recovered from other non-REEs (Fe2+ and Co2+) in a NdFeB magnet simulant solution (at pH 6).
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Affiliation(s)
- Farid Khoury
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Zihang Su
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
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2
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Jung H, Su Z, Inaba Y, West AC, Banta S. Genetic Modification of Acidithiobacillus ferrooxidans for Rare-Earth Element Recovery under Acidic Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:19902-19911. [PMID: 37983372 DOI: 10.1021/acs.est.3c05772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
As global demands for rare-earth elements (REEs) continue to grow, the biological recovery of REEs has been explored as a promising strategy, driven by potential economic and environmental benefits. It is known that calcium-binding domains, including helix-loop-helix EF hands and repeats-in-toxin (RTX) domains, can bind lanthanide ions due to their similar ionic radii and coordination preference to calcium. Recently, the lanmodulin protein from Methylorubrum extorquens was reported, which has evolved a high affinity for lanthanide ions over calcium. Acidithiobacillus ferrooxidans is a chemolithoautotrophic acidophile, which has been explored for use in bioleaching for metal recovery. In this report, A. ferrooxidans was engineered for the recombinant intracellular expression of lanmodulin. In addition, an RTX domain from the adenylate cyclase protein of Bordetella pertussis, which has previously been shown to bind Tb3+, was expressed periplasmically via fusion with the endogenous rusticyanin protein. The binding of lanthanides (Tb3+, Pr3+, Nd3+, and La3+) was improved by up to 4-fold for cells expressing lanmodulin and 13-fold for cells expressing the RTX domains in both pure and mixed metal solutions. Interestingly, the presence of lanthanides in the growth media enhanced protein expression, likely by influencing protein stability. Both engineered cell lines exhibited higher recoveries and selectivities for four tested lanthanides (Tb3+, Pr3+, Nd3+, and La3+) over non-REEs (Fe2+ and Co2+) in a synthetic magnet leachate, demonstrating the potential of these new strains for future REE reclamation and recycling applications.
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Affiliation(s)
- Heejung Jung
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, United States
| | - Zihang Su
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, United States
| | - Yuta Inaba
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, United States
| | - Alan C West
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, New York 10027, United States
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3
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Agaras BC, Grossi CEM, Ulloa RM. Unveiling the Secrets of Calcium-Dependent Proteins in Plant Growth-Promoting Rhizobacteria: An Abundance of Discoveries Awaits. PLANTS (BASEL, SWITZERLAND) 2023; 12:3398. [PMID: 37836138 PMCID: PMC10574481 DOI: 10.3390/plants12193398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/20/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023]
Abstract
The role of Calcium ions (Ca2+) is extensively documented and comprehensively understood in eukaryotic organisms. Nevertheless, emerging insights, primarily derived from studies on human pathogenic bacteria, suggest that this ion also plays a pivotal role in prokaryotes. In this review, our primary focus will be on unraveling the intricate Ca2+ toolkit within prokaryotic organisms, with particular emphasis on its implications for plant growth-promoting rhizobacteria (PGPR). We undertook an in silico exploration to pinpoint and identify some of the proteins described in the existing literature, including prokaryotic Ca2+ channels, pumps, and exchangers that are responsible for regulating intracellular Calcium concentration ([Ca2+]i), along with the Calcium-binding proteins (CaBPs) that play a pivotal role in sensing and transducing this essential cation. These investigations were conducted in four distinct PGPR strains: Pseudomonas chlororaphis subsp. aurantiaca SMMP3, P. donghuensis SVBP6, Pseudomonas sp. BP01, and Methylobacterium sp. 2A, which have been isolated and characterized within our research laboratories. We also present preliminary experimental data to evaluate the influence of exogenous Ca2+ concentrations ([Ca2+]ex) on the growth dynamics of these strains.
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Affiliation(s)
- Betina Cecilia Agaras
- Laboratory of Physiology and Genetics of Plant Probiotic Bacteria (LFGBBP), Centre of Biochemistry and Microbiology of Soils, National University of Quilmes, Bernal B1876BXD, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
| | - Cecilia Eugenia María Grossi
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
- Laboratory of Plant Signal Transduction, Institute of Genetic Engineering and Molecular Biology (INGEBI), National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
| | - Rita María Ulloa
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
- Laboratory of Plant Signal Transduction, Institute of Genetic Engineering and Molecular Biology (INGEBI), National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
- Biochemistry Department, Faculty of Exact and Natural Sciences, University of Buenos Aires (FCEN-UBA), Buenos Aires C1428EGA, Argentina
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4
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Filipi K, Rahman WU, Osickova A, Osicka R. Kingella kingae RtxA Cytotoxin in the Context of Other RTX Toxins. Microorganisms 2022; 10:518. [PMID: 35336094 PMCID: PMC8953716 DOI: 10.3390/microorganisms10030518] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/04/2022] Open
Abstract
The Gram-negative bacterium Kingella kingae is part of the commensal oropharyngeal flora of young children. As detection methods have improved, K. kingae has been increasingly recognized as an emerging invasive pathogen that frequently causes skeletal system infections, bacteremia, and severe forms of infective endocarditis. K. kingae secretes an RtxA cytotoxin, which is involved in the development of clinical infection and belongs to an ever-growing family of cytolytic RTX (Repeats in ToXin) toxins secreted by Gram-negative pathogens. All RTX cytolysins share several characteristic structural features: (i) a hydrophobic pore-forming domain in the N-terminal part of the molecule; (ii) an acylated segment where the activation of the inactive protoxin to the toxin occurs by a co-expressed toxin-activating acyltransferase; (iii) a typical calcium-binding RTX domain in the C-terminal portion of the molecule with the characteristic glycine- and aspartate-rich nonapeptide repeats; and (iv) a C-proximal secretion signal recognized by the type I secretion system. RTX toxins, including RtxA from K. kingae, have been shown to act as highly efficient 'contact weapons' that penetrate and permeabilize host cell membranes and thus contribute to the pathogenesis of bacterial infections. RtxA was discovered relatively recently and the knowledge of its biological role remains limited. This review describes the structure and function of RtxA in the context of the most studied RTX toxins, the knowledge of which may contribute to a better understanding of the action of RtxA in the pathogenesis of K. kingae infections.
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Affiliation(s)
| | | | | | - Radim Osicka
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic; (K.F.); (W.U.R.); (A.O.)
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5
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Chang MP, Huang W, Mai DJ. Monomer‐scale design of functional protein polymers using consensus repeat sequences. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Marina P. Chang
- Department of Materials Science and Engineering Stanford University Stanford California USA
| | - Winnie Huang
- Department of Chemical Engineering Stanford University Stanford California USA
| | - Danielle J. Mai
- Department of Chemical Engineering Stanford University Stanford California USA
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6
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Structural basis for antibody binding to adenylate cyclase toxin reveals RTX linkers as neutralization-sensitive epitopes. PLoS Pathog 2021; 17:e1009920. [PMID: 34547035 PMCID: PMC8486122 DOI: 10.1371/journal.ppat.1009920] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 10/01/2021] [Accepted: 08/27/2021] [Indexed: 11/19/2022] Open
Abstract
RTX leukotoxins are a diverse family of prokaryotic virulence factors that are secreted by the type 1 secretion system (T1SS) and target leukocytes to subvert host defenses. T1SS substrates all contain a C-terminal RTX domain that mediates recruitment to the T1SS and drives secretion via a Brownian ratchet mechanism. Neutralizing antibodies against the Bordetella pertussis adenylate cyclase toxin, an RTX leukotoxin essential for B. pertussis colonization, have been shown to target the RTX domain and prevent binding to the αMβ2 integrin receptor. Knowledge of the mechanisms by which antibodies bind and neutralize RTX leukotoxins is required to inform structure-based design of bacterial vaccines, however, no structural data are available for antibody binding to any T1SS substrate. Here, we determine the crystal structure of an engineered RTX domain fragment containing the αMβ2-binding site bound to two neutralizing antibodies. Notably, the receptor-blocking antibodies bind to the linker regions of RTX blocks I–III, suggesting they are key neutralization-sensitive sites within the RTX domain and are likely involved in binding the αMβ2 receptor. As the engineered RTX fragment contained these key epitopes, we assessed its immunogenicity in mice and showed that it elicits similar neutralizing antibody titers to the full RTX domain. The results from these studies will support the development of bacterial vaccines targeting RTX leukotoxins, as well as next-generation B. pertussis vaccines. Diverse bacterial pathogens use the type 1 secretion system (T1SS) to secrete RTX leukotoxins, which target host leukocytes during infection. T1SS substrates all contain a repetitive C-terminal ‘RTX’ domain that adopts a characteristic β-roll fold and is involved in secretion. Notably, The RTX domain of Bordetella pertussis adenylate cyclase toxin (ACT) mediates leukocyte targeting via binding to the αMβ2 integrin receptor, and antibodies that block receptor binding neutralize toxin activity. However, ACT also contains multiple non-neutralizing epitopes, and precise knowledge of the sites targeted by neutralizing antibodies is desirable for vaccine design. Here we determine the crystal structure of an ACT fragment in complex with two neutralizing antibodies and define the key neutralization-sensitive sites within the RTX domain. This first structure of a heterotypic protein–protein interaction formed by an RTX domain suggests the linker regions between β-roll segments engage binding partners.
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7
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Recent advances in tuning the expression and regulation of genes for constructing microbial cell factories. Biotechnol Adv 2021; 50:107767. [PMID: 33974979 DOI: 10.1016/j.biotechadv.2021.107767] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/29/2021] [Accepted: 05/05/2021] [Indexed: 12/14/2022]
Abstract
To overcome environmental problems caused by the use of fossil resources, microbial cell factories have become a promising technique for the sustainable and eco-friendly development of valuable products from renewable resources. Constructing microbial cell factories with high titers, yields, and productivity requires a balance between growth and production; to this end, tuning gene expression and regulation is necessary to optimise and precisely control complicated metabolic fluxes. In this article, we review the current trends and advances in tuning gene expression and regulation and consider their engineering at each of the three stages of gene regulation: genomic, mRNA, and protein. In particular, the technological approaches utilised in a diverse range of genetic-engineering-based tools for the construction of microbial cell factories are reviewed and representative applications of these strategies are presented. Finally, the prospects for strategies and systems for tuning gene expression and regulation are discussed.
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8
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Ali NSM, Salleh AB, Leow TC, Rahman RNZRA, Ali MSM. The Influence of Calcium toward Order/Disorder Conformation of Repeat-in-Toxin (RTX) Structure of Family I.3 Lipase from Pseudomonas fluorescens AMS8. Toxins (Basel) 2020; 12:toxins12090579. [PMID: 32916891 PMCID: PMC7551394 DOI: 10.3390/toxins12090579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/10/2020] [Accepted: 08/17/2020] [Indexed: 11/16/2022] Open
Abstract
Calcium-binding plays a decisive role in the folding and stabilization of many RTX proteins, especially for the RTX domain. Although many studies have been conducted to prove the contribution of Ca2+ ion toward the folding and stabilization of RTX proteins, its functional dynamics and conformational structural changes remain elusive. Here, molecular docking and molecular dynamics (MD) simulations were performed to analyze the contribution of Ca2+ ion toward the folding and stabilization of the RTX lipase (AMS8 lipase) structure. AMS8 lipase contains six Ca2+ ions (Ca1–Ca6). Three Ca2+ ions (Ca3, Ca4, and Ca5) were bound to the RTX parallel β-roll motif repeat structure (RTX domain). The metal ion (Ca2+) docking analysis gives a high binding energy, especially for Ca4 and Ca5 which are tightly bound to the RTX domain. The function of each Ca2+ ion is further analyzed using the MD simulation. The removal of Ca3, Ca4, and Ca5 caused the AMS8 lipase structure to become unstable and unfolded. The results suggested that Ca3, Ca4, and Ca5 stabilized the RTX domain. In conclusion, Ca3, Ca4, and Ca5 play a crucial role in the folding and stabilization of the RTX domain, which sustain the integrity of the overall AMS8 lipase structure.
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Affiliation(s)
- Nur Shidaa Mohd Ali
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (N.S.M.A.); (A.B.S.); (T.C.L.); (R.N.Z.R.A.R.)
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Abu Bakar Salleh
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (N.S.M.A.); (A.B.S.); (T.C.L.); (R.N.Z.R.A.R.)
| | - Thean Chor Leow
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (N.S.M.A.); (A.B.S.); (T.C.L.); (R.N.Z.R.A.R.)
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Raja Noor Zaliha Raja Abd Rahman
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (N.S.M.A.); (A.B.S.); (T.C.L.); (R.N.Z.R.A.R.)
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Mohd Shukuri Mohamad Ali
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (N.S.M.A.); (A.B.S.); (T.C.L.); (R.N.Z.R.A.R.)
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
- Correspondence:
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Baumann U. Structure-Function Relationships of the Repeat Domains of RTX Toxins. Toxins (Basel) 2019; 11:toxins11110657. [PMID: 31718085 PMCID: PMC6891781 DOI: 10.3390/toxins11110657] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/07/2019] [Accepted: 11/09/2019] [Indexed: 01/08/2023] Open
Abstract
RTX proteins are a large family of polypeptides of mainly Gram-negative origin that are secreted into the extracellular medium by a type I secretion system featuring a non-cleavable C-terminal secretion signal, which is preceded by a variable number of nine-residue tandem repeats. The three-dimensional structure forms a parallel β-roll, where β-strands of two parallel sheets are connected by calcium-binding linkers in such a way that a right-handed spiral is built. The Ca2+ ions are an integral part of the structure, which cannot form without them. The structural determinants of this unique architecture will be reviewed with its conservations and variations together with the implication for secretion and folding of these proteins. The general purpose of the RTX domains appears to act as an internal chaperone that keeps the polypeptide unfolded in the calcium-deprived cytosol and triggers folding in the calcium-rich extracellular medium. A rather recent addition to the structural biology of the RTX toxin is a variant occurring in a large RTX adhesin, where this non-canonical β-roll binds to ice and diatoms.
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Affiliation(s)
- Ulrich Baumann
- Institute of Biochemistry, University of Cologne, Zülpicherstrasse 47, D-50674 Cologne, Germany
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10
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Abstract
Type I secretion systems (T1SS) are widespread in Gram-negative bacteria, especially in pathogenic bacteria, and they secrete adhesins, iron-scavenger proteins, lipases, proteases, or pore-forming toxins in the unfolded state in one step across two membranes without any periplasmic intermediate into the extracellular space. The substrates of T1SS are in general characterized by a C-terminal secretion sequence and nonapeptide repeats, so-called GG repeats, located N terminal to the secretion sequence. These GG repeats bind Ca2+ ions in the extracellular space, which triggers folding of the entire protein. Here we summarize our current knowledge of how Gram-negative bacteria secrete these substrates, which can possess a molecular mass of up to 1,500 kDa. We also describe recent findings that demonstrate that the absence of periplasmic intermediates, the "classic" mode of action, does not hold true for all T1SS and that we are beginning to realize modifications of a common theme.
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Bulutoglu B, Banta S. Calcium-Dependent RTX Domains in the Development of Protein Hydrogels. Gels 2019; 5:E10. [PMID: 30823512 PMCID: PMC6473919 DOI: 10.3390/gels5010010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 12/12/2022] Open
Abstract
The RTX domains found in some pathogenic proteins encode repetitive peptide sequences that reversibly bind calcium and fold into the unique the β-roll secondary structure. Several of these domains have been studied in isolation, yielding key insights into their structure/function relationships. These domains are increasingly being used in protein engineering applications, where the calcium-induced control over structure can be exploited to gain new functions. Here we review recent advances in the use of RTX domains in the creation of calcium responsive biomaterials.
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Affiliation(s)
- Beyza Bulutoglu
- Department of Chemical Engineering, Columbia University, 500 W 120th Street, New York, NY 10027, USA.
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, 500 W 120th Street, New York, NY 10027, USA.
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12
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Abdallah W, Solanki K, Banta S. Insertion of a Calcium-Responsive β-Roll Domain into a Thermostable Alcohol Dehydrogenase Enables Tunable Control over Cofactor Selectivity. ACS Catal 2018. [DOI: 10.1021/acscatal.7b03809] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Walaa Abdallah
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Kusum Solanki
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
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13
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Liu L, Wang H, Han Y, Lv S, Chen J. Using single molecule force spectroscopy to facilitate a rational design of Ca2+-responsive β-roll peptide-based hydrogels. J Mater Chem B 2018; 6:5303-5312. [DOI: 10.1039/c8tb01511b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mechanical stability of Ca2+-responsive β-roll peptides (RTX) is largely responsible for the Ca2+-dependent mechanical properties of the RTX-based hydrogels.
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Affiliation(s)
- Lichao Liu
- State Key Laboratory of Organic–Inorganic Composite Materials
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Han Wang
- Department of Chemistry
- The University of British Columbia
- Vancouver
- Canada
| | - Yueying Han
- State Key Laboratory of Organic–Inorganic Composite Materials
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Shanshan Lv
- State Key Laboratory of Organic–Inorganic Composite Materials
- Beijing University of Chemical Technology
- Beijing 100029
- China
- Department of Chemistry
| | - Jianfeng Chen
- State Key Laboratory of Organic–Inorganic Composite Materials
- Beijing University of Chemical Technology
- Beijing 100029
- China
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Type I Protein Secretion-Deceptively Simple yet with a Wide Range of Mechanistic Variability across the Family. EcoSal Plus 2017; 7. [PMID: 28084193 DOI: 10.1128/ecosalplus.esp-0019-2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A very large type I polypeptide begins to reel out from a ribosome; minutes later, the still unidentifiable polypeptide, largely lacking secondary structure, is now in some cases a thousand or more residues longer. Synthesis of the final hundred C-terminal residues commences. This includes the identity code, the secretion signal within the last 50 amino acids, designed to dock with a waiting ATP binding cassette (ABC) transporter. What happens next is the subject of this review, with the main, but not the only focus on hemolysin HlyA, an RTX protein toxin secreted by the type I system. Transport substrates range from small peptides to giant proteins produced by many pathogens. These molecules, without detectable cellular chaperones, overcome enormous barriers, crossing two membranes before final folding on the cell surface, involving a unique autocatalytic process.Unfolded HlyA is extruded posttranslationally, C-terminal first. The transenvelope "tunnel" is formed by HlyB (ABC transporter), HlyD (membrane fusion protein) straddling the inner membrane and periplasm and TolC (outer membrane). We present a new evaluation of the C-terminal secretion code, and the structure function of HlyD and HlyB at the heart of this nanomachine. Surprisingly, key details of the secretion mechanism are remarkably variable in the many type I secretion system subtypes. These include alternative folding processes, an apparently distinctive secretion code for each type I subfamily, and alternative forms of the ABC transporter; most remarkably, the ABC protein probably transports peptides or polypeptides by quite different mechanisms. Finally, we suggest a putative structure for the Hly-translocon, HlyB, the multijointed HlyD, and the TolC exit.
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15
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Bulutoglu B, Banta S. Block V RTX Domain of Adenylate Cyclase from Bordetella pertussis: A Conformationally Dynamic Scaffold for Protein Engineering Applications. Toxins (Basel) 2017; 9:E289. [PMID: 28926974 PMCID: PMC5618222 DOI: 10.3390/toxins9090289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/12/2017] [Accepted: 09/12/2017] [Indexed: 01/27/2023] Open
Abstract
The isolated Block V repeats-in-toxin (RTX) peptide domain of adenylate cyclase (CyaA) from Bordetella pertussis reversibly folds into a β-roll secondary structure upon calcium binding. In this review, we discuss how the conformationally dynamic nature of the peptide is being engineered and employed as a switching mechanism to mediate different protein functions and protein-protein interactions. The peptide has been used as a scaffold for diverse applications including: a precipitation tag for bioseparations, a cross-linking domain for protein hydrogel formation and as an alternative scaffold for biomolecular recognition applications. Proteins and peptides such as the RTX domains that exhibit natural stimulus-responsive behavior are valuable building blocks for emerging synthetic biology applications.
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Affiliation(s)
- Beyza Bulutoglu
- Department of Chemical Engineering, Columbia University, 500 W 120th Street, New York, NY 10027, USA
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, 500 W 120th Street, New York, NY 10027, USA.
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16
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Bulutoglu B, Dooley K, Szilvay G, Blenner M, Banta S. Catch and Release: Engineered Allosterically Regulated β-Roll Peptides Enable On/Off Biomolecular Recognition. ACS Synth Biol 2017; 6:1732-1741. [PMID: 28520402 DOI: 10.1021/acssynbio.7b00089] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alternative scaffolds for biomolecular recognition are being developed to overcome some of the limitations associated with immunoglobulin domains. The repeat-in-toxin (RTX) domain is a repeat protein sequence that reversibly adopts the β-roll secondary structure motif specifically upon calcium binding. This conformational change was exploited for controlled biomolecular recognition. Using ribosome display, an RTX peptide library was selected to identify binders to a model protein, lysozyme, exclusively in the folded state of the peptide. Several mutants were identified with low micromolar dissociation constants. After concatenation of the mutants, a 500-fold increase in the overall affinity for lysozyme was achieved leading to a peptide with an apparent dissociation constant of 65 nM. This mutant was immobilized for affinity chromatography experiments, and the on/off nature of the molecular recognition was demonstrated as the target is captured from a mixture in the presence of calcium and is released in the absence of calcium as the RTX peptides lose their β-roll structure. This work presents the design of a new stimulus-responsive scaffold that can be used for environmentally responsive specific molecular recognition and self-assembly.
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Affiliation(s)
- Beyza Bulutoglu
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Kevin Dooley
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Géza Szilvay
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Mark Blenner
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
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17
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Hepp C, Maier B. Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules. Bioessays 2017; 39. [PMID: 28895164 DOI: 10.1002/bies.201700099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/02/2017] [Indexed: 12/20/2022]
Abstract
Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism.
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Affiliation(s)
- Christof Hepp
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
| | - Berenike Maier
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
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18
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Bulutoglu B, Yang SJ, Banta S. Conditional Network Assembly and Targeted Protein Retention via Environmentally Responsive, Engineered β-Roll Peptides. Biomacromolecules 2017; 18:2139-2145. [PMID: 28578565 DOI: 10.1021/acs.biomac.7b00457] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Beyza Bulutoglu
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, Room 801, New York, New York 10027, United States
| | - Sarah J. Yang
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, Room 801, New York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, Room 801, New York, New York 10027, United States
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19
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Wang X, Stapleton JA, Klesmith JR, Hewlett EL, Whitehead TA, Maynard JA. Fine Epitope Mapping of Two Antibodies Neutralizing the Bordetella Adenylate Cyclase Toxin. Biochemistry 2017; 56:1324-1336. [PMID: 28177609 DOI: 10.1021/acs.biochem.6b01163] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adenylate cyclase toxin (ACT) is an important Bordetella pertussis virulence factor that is not included in current acellular pertussis vaccines. We previously demonstrated that immunization with the repeat-in-toxin (RTX) domain of ACT elicits neutralizing antibodies in mice and discovered the first two antibodies to neutralize ACT activities by occluding the receptor-binding site. Here, we fully characterize these antibodies and their epitopes. Both antibodies bind ACT with low nanomolar affinity and cross-react with ACT homologues produced by B. parapertussis and B. bronchiseptica. Antibody M1H5 binds B. pertussis RTX751 ∼100-fold tighter than RTX751 from the other two species, while antibody M2B10 has similar affinity for all three variants. To initially map the antibody epitopes, we generated a series of ACT chimeras and truncation variants, which implicated the repeat blocks II-III. To identify individual epitope residues, we displayed randomly mutated RTX751 libraries on yeast and isolated clones with decreased antibody binding by flow cytometry. Next-generation sequencing identified candidate epitope residues on the basis of enrichment of clones with mutations at specific positions. These epitopes form two adjacent surface patches on a predicted structural model of the RTX751 domain, one for each antibody. Notably, the cellular receptor also binds within blocks II-III and shares at least one residue with the M1H5 epitope. The RTX751 model supports the notion that the antibody and receptor epitopes overlap. These data provide insight into mechanisms of ACT neutralization and guidance for engineering more stable RTX variants that may be more appropriate vaccine antigens.
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Affiliation(s)
- Xianzhe Wang
- Department of Chemical Engineering, University of Texas at Austin , Austin, Texas 78712, United States
| | - James A Stapleton
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan 48824, United States
| | - Justin R Klesmith
- Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States
| | - Erik L Hewlett
- Department of Medicine, University of Virginia , Charlottesville, Virginia 22906, United States
| | - Timothy A Whitehead
- Department of Chemical Engineering and Materials Science, Michigan State University , East Lansing, Michigan 48824, United States.,Department of Biosystems and Agricultural Engineering, Michigan State University , East Lansing, Michigan 48824, United States
| | - Jennifer A Maynard
- Department of Chemical Engineering, University of Texas at Austin , Austin, Texas 78712, United States
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20
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Lenders MHH, Beer T, Smits SHJ, Schmitt L. In vivo quantification of the secretion rates of the hemolysin A Type I secretion system. Sci Rep 2016; 6:33275. [PMID: 27616645 PMCID: PMC5018854 DOI: 10.1038/srep33275] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/24/2016] [Indexed: 01/08/2023] Open
Abstract
Type 1 secretion systems (T1SS) of Gram-negative bacteria secrete a broad range of substrates into the extracellular space. Common to all substrates is a C-terminal secretion sequence and nonapeptide repeats in the C-terminal part that bind Ca2+ in the extracellular space, to trigger protein folding. Like all T1SS, the hemolysin A (HlyA) T1SS of Escherichia coli consists of an ABC transporter, a membrane fusion protein and an outer membrane protein allowing the one step translocation of the substrate across both membranes. Here, we analyzed the secretion rate of the HlyA T1SS. Our results demonstrate that the rate is independent of substrate-size and operates at a speed of approximately 16 amino acids per transporter per second. We also demonstrate that the rate is independent of the extracellular Ca2+ concentration raising the question of the driving force of substrate secretion by T1SS in general.
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Affiliation(s)
- Michael H H Lenders
- Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany
| | - Tobias Beer
- Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany
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21
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Bumba L, Masin J, Macek P, Wald T, Motlova L, Bibova I, Klimova N, Bednarova L, Veverka V, Kachala M, Svergun D, Barinka C, Sebo P. Calcium-Driven Folding of RTX Domain β-Rolls Ratchets Translocation of RTX Proteins through Type I Secretion Ducts. Mol Cell 2016; 62:47-62. [DOI: 10.1016/j.molcel.2016.03.018] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 12/31/2015] [Accepted: 03/15/2016] [Indexed: 11/17/2022]
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22
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Tang C, Lew S, He D. Using a second-order differential model to fit data without baselines in protein isothermal chemical denaturation. Protein Sci 2016; 25:898-904. [PMID: 26757366 DOI: 10.1002/pro.2878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/21/2015] [Accepted: 12/23/2015] [Indexed: 11/06/2022]
Abstract
In vitro protein stability studies are commonly conducted via thermal or chemical denaturation/renaturation of protein. Conventional data analyses on the protein unfolding/(re)folding require well-defined pre- and post-transition baselines to evaluate Gibbs free-energy change associated with the protein unfolding/(re)folding. This evaluation becomes problematic when there is insufficient data for determining the pre- or post-transition baselines. In this study, fitting on such partial data obtained in protein chemical denaturation is established by introducing second-order differential (SOD) analysis to overcome the limitations that the conventional fitting method has. By reducing numbers of the baseline-related fitting parameters, the SOD analysis can successfully fit incomplete chemical denaturation data sets with high agreement to the conventional evaluation on the equivalent completed data, where the conventional fitting fails in analyzing them. This SOD fitting for the abbreviated isothermal chemical denaturation further fulfills data analysis methods on the insufficient data sets conducted in the two prevalent protein stability studies.
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Affiliation(s)
- Chuanning Tang
- Key Laboratory of Cell Proliferation and Regulation of Ministry of Education, Beijing Normal University, Beijing, 100875, China
| | - Scott Lew
- Neotein Therapeutics, New York, New York, 10706, USA
| | - Dacheng He
- Key Laboratory of Cell Proliferation and Regulation of Ministry of Education, Beijing Normal University, Beijing, 100875, China
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23
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Gavin HE, Satchell KJF. MARTX toxins as effector delivery platforms. Pathog Dis 2015; 73:ftv092. [PMID: 26472741 DOI: 10.1093/femspd/ftv092] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2015] [Indexed: 12/14/2022] Open
Abstract
Bacteria frequently manipulate their host environment via delivery of microbial 'effector' proteins to the cytosol of eukaryotic cells. In the case of the multifunctional autoprocessing repeats-in-toxins (MARTX) toxin, this phenomenon is accomplished by a single, >3500 amino acid polypeptide that carries information for secretion, translocation, autoprocessing and effector activity. MARTX toxins are secreted from bacteria by dedicated Type I secretion systems. The released MARTX toxins form pores in target eukaryotic cell membranes for the delivery of up to five cytopathic effectors, each of which disrupts a key cellular process. Targeted cellular processes include modulation or modification of small GTPases, manipulation of host cell signaling and disruption of cytoskeletal integrity. More recently, MARTX toxins have been shown to be capable of heterologous protein translocation. Found across multiple bacterial species and genera--frequently in pathogens lacking Type 3 or Type 4 secretion systems--MARTX toxins in multiple cases function as virulence factors. Innovative research at the intersection of toxin biology and bacterial genetics continues to elucidate the intricacies of the toxin as well as the cytotoxic mechanisms of its diverse effector collection.
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Affiliation(s)
- Hannah E Gavin
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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24
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Distinct roles of the repeat-containing regions and effector domains of the Vibrio vulnificus multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin. mBio 2015; 6:mBio.00324-15. [PMID: 25827415 PMCID: PMC4453568 DOI: 10.1128/mbio.00324-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Vibrio vulnificus is a seafood-borne pathogen that destroys the intestinal epithelium, leading to rapid bacterial dissemination and death. The most important virulence factor is the multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin comprised of effector domains in the center region flanked by long repeat-containing regions which are well conserved among MARTX toxins and predicted to translocate effector domains. Here, we examined the role of the repeat-containing regions using a modified V. vulnificus MARTX (MARTXVv) toxin generated by replacing all the internal effector domains with β-lactamase (Bla). Bla activity was detected in secretions from the bacterium and also in the cytosol of intoxicated epithelial cells. The modified MARTXVv toxin without effector domains retained its necrotic activity but lost its cell-rounding activity. Further, deletion of the carboxyl-terminal repeat-containing region blocked toxin secretion from the bacterium. Deletion of the amino-terminal repeat-containing region had no effect on secretion but completely abolished translocation and necrosis. Neither secretion nor translocation was affected by enzymatically inactivating the cysteine protease domain of the toxin. These data demonstrate that the amino-terminal and carboxyl-terminal repeat-containing regions of the MARTXVv toxin are necessary and sufficient for the delivery of effector domains and epithelial cell lysis in vitro but that effector domains are required for other cytopathic functions. Furthermore, Ca2+-dependent secretion of the modified MARTXVv toxin suggests that nonclassical RTX-like repeats found in the carboxyl-terminal repeat-containing region are functionally similar to classical RTX repeats found in other RTX proteins. Up to 95% of deaths from seafood-borne infections in the United States are due solely to one pathogen, V. vulnificus. Among its various virulence factors, the MARTXVv toxin has been characterized as a critical exotoxin for successful pathogenesis of V. vulnificus in mouse infection models. Similarly to MARTX toxins of other pathogens, MARTXVv toxin is comprised of repeat-containing regions, central effector domains, and an autoprocessing cysteine protease domain. Yet how each of these regions contributes to essential activities of the toxins has not been fully identified for any of MARTX toxins. Using modified MARTXVv toxin fused with β-lactamase as a reporter enzyme, the portion(s) responsible for toxin secretion from bacteria, effector domain translocation into host cells, rapid host cell rounding, and necrotic host cell death was identified. The results are relevant for understanding how MARTXVv toxin serves as both a necrotic pore-forming toxin and an effector delivery platform.
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25
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Disorder-to-order transition in the CyaA toxin RTX domain: implications for toxin secretion. Toxins (Basel) 2014; 7:1-20. [PMID: 25559101 PMCID: PMC4303809 DOI: 10.3390/toxins7010001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 12/24/2014] [Indexed: 11/23/2022] Open
Abstract
The past decade has seen a fundamental reappraisal of the protein structure-to-function paradigm because it became evident that a significant fraction of polypeptides are lacking ordered structures under physiological conditions. Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by RTX (Repeat in ToXin) motifs found in more than 250 virulence factors secreted by Gram-negative pathogenic bacteria. We have investigated several RTX-containing polypeptides of different lengths, all derived from the Bordetella pertussis adenylate cyclase toxin, CyaA. Using a combination of experimental approaches, we showed that the RTX proteins exhibit the hallmarks of intrinsically disordered proteins in the absence of calcium. This intrinsic disorder mainly results from internal electrostatic repulsions between negatively charged residues of the RTX motifs. Calcium binding triggers a strong reduction of the mean net charge, dehydration and compaction, folding and stabilization of secondary and tertiary structures of the RTX proteins. We propose that the intrinsically disordered character of the RTX proteins may facilitate the uptake and secretion of virulence factors through the bacterial secretion machinery. These results support the hypothesis that the folding reaction is achieved upon protein secretion and, in the case of proteins containing RTX motifs, could be finely regulated by the calcium gradient across bacterial cell wall.
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26
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Hendrix J, Read T, Lalonde JF, Jensen PK, Heymann W, Lovelace E, Zimmermann SA, Brasino M, Rokicki J, Dowell RD. Engineered calcium-precipitable restriction enzyme. ACS Synth Biol 2014; 3:969-71. [PMID: 25524101 DOI: 10.1021/sb500042m] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed a simple system for tagging and purifying proteins. Recent experiments have demonstrated that RTX (Repeat in Toxin) motifs from the adenylate cyclase toxin gene (CyaA) of B. pertussis undergo a conformational change upon binding calcium, resulting in precipitation of fused proteins and making this method a viable alternative for bioseparation. We have designed an iGEM Biobrick comprised of an RTX tag that can be easily fused to any protein of interest. In this paper, we detail the process of creating an RTX tagged version of the restriction enzyme EcoRI and describe a method for expression and purification of the functional enzyme.
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Affiliation(s)
- Josephina Hendrix
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Timothy Read
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Jean-Francois Lalonde
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Phillip K. Jensen
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - William Heymann
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Elijah Lovelace
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Sarah A. Zimmermann
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Michael Brasino
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Joseph Rokicki
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Robin D. Dowell
- Department
of Molecular, Cellular, and Developmental Biology, ‡Department of Chemical
and Biological Engineering, §Department of Chemistry and Biochemistry, ∥BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, United States
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27
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Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2014; 57:151-65. [PMID: 25555683 DOI: 10.1016/j.ceca.2014.12.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.
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28
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Wang X, Gray MC, Hewlett EL, Maynard JA. The Bordetella adenylate cyclase repeat-in-toxin (RTX) domain is immunodominant and elicits neutralizing antibodies. J Biol Chem 2014; 290:3576-91. [PMID: 25505186 DOI: 10.1074/jbc.m114.585281] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The adenylate cyclase toxin (ACT) is a multifunctional virulence factor secreted by Bordetella species. Upon interaction of its C-terminal hemolysin moiety with the cell surface receptor αMβ2 integrin, the N-terminal cyclase domain translocates into the host cell cytosol where it rapidly generates supraphysiological cAMP concentrations, which inhibit host cell anti-bacterial activities. Although ACT has been shown to induce protective immunity in mice, it is not included in any current acellular pertussis vaccines due to protein stability issues and a poor understanding of its role as a protective antigen. Here, we aimed to determine whether any single domain could recapitulate the antibody responses induced by the holo-toxin and to characterize the dominant neutralizing antibody response. We first immunized mice with ACT and screened antibody phage display libraries for binding to purified ACT. The vast majority of unique antibodies identified bound the C-terminal repeat-in-toxin (RTX) domain. Representative antibodies binding two nonoverlapping, neutralizing epitopes in the RTX domain prevented ACT association with J774A.1 macrophages and soluble αMβ2 integrin, suggesting that these antibodies inhibit the ACT-receptor interaction. Sera from mice immunized with the RTX domain showed similar neutralizing activity as ACT-immunized mice, indicating that this domain induced an antibody response similar to that induced by ACT. These data demonstrate that RTX can elicit neutralizing antibodies and suggest it may present an alternative to ACT.
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Affiliation(s)
| | - Mary C Gray
- Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Erik L Hewlett
- Division of Infectious Diseases and International Health, Deparment of Medicine, University of Virginia, Charlottesville, Virginia, 22908
| | - Jennifer A Maynard
- Division of Infectious Diseases and International Health, Deparment of Medicine, University of Virginia, Charlottesville, Virginia, 22908
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29
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Dooley K, Bulutoglu B, Banta S. Doubling the cross-linking interface of a rationally designed beta roll peptide for calcium-dependent proteinaceous hydrogel formation. Biomacromolecules 2014; 15:3617-24. [PMID: 25226243 DOI: 10.1021/bm500870a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We have rationally engineered a stimulus-responsive cross-linking domain based on a repeats-in-toxin (RTX) peptide to enable calcium-dependent formation of supramolecular hydrogel networks. The peptide isolated from the RTX domain is intrinsically disordered in the absence of calcium. In calcium rich environments, the peptide binds Ca(2+) ions and folds into a beta roll (β-roll) secondary structure composed to two parallel β-sheet faces. Previously, we mutated one of the faces to contain solvent exposed leucine side chains which are localized only in the calcium-bound β-roll conformation. We demonstrated the ability of this mutant peptide to self-assemble into hydrogels in the presence of calcium with the aid of additional peptide-based cross-linking moieties. Here, we have expanded this approach by engineering both β-roll faces to contain leucine residues, thereby doubling the cross-linking interface for each monomeric building block. These leucine rich surfaces impart a hydrophobic driving force for self-assembly. Extensive characterization was performed on this double-faced mutant to ensure the retention of calcium affinity and subsequent structural rearrangement similar to that of the wild type domain. We genetically fused an α-helical leucine zipper capable of forming tetrameric coiled-coil bundles to the peptide and the resulting chimeric protein self-assembles into a hydrogel only in calcium rich environments. Since this new mutant peptide enables cross-linking on both surfaces simultaneously, a higher oligomerization state was achieved. To further investigate the cross-linking capability, we constructed concatemers of the β-roll with maltose binding protein (MBP), a monomeric globular protein, without the leucine zipper domains. These concatemers show a similar sol-gel transition in response to calcium. Several biophysical techniques were used to probe the structural and mechanical properties of the mutant β-roll domain and the resulting supramolecular networks including circular dichroism, fluorescence resonance energy transfer, bis-ANS binding, and microrheology. These results demonstrate that the engineered β-roll peptides can mediate calcium-dependent cross-linking for protein hydrogel formation without the need for any other cross-linking moieties.
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Affiliation(s)
- Kevin Dooley
- Department of Chemical Engineering, Columbia University , New York, New York 10027, United States
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30
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Thomas S, Bakkes PJ, Smits SHJ, Schmitt L. Equilibrium folding of pro-HlyA from Escherichia coli reveals a stable calcium ion dependent folding intermediate. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1500-10. [PMID: 24865936 DOI: 10.1016/j.bbapap.2014.05.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 11/17/2022]
Abstract
HlyA from Escherichia coli is a member of the repeats in toxin (RTX) protein family, produced by a wide range of Gram-negative bacteria and secreted by a dedicated Type 1 Secretion System (T1SS). RTX proteins are thought to be secreted in an unfolded conformation and to fold upon secretion by Ca(2+) binding. However, the exact mechanism of secretion, ion binding and folding to the correct native state remains largely unknown. In this study we provide an easy protocol for high-level pro-HlyA purification from E. coli. Equilibrium folding studies, using intrinsic tryptophan fluorescence, revealed the well-known fact that Ca(2+) is essential for stability as well as correct folding of the whole protein. In the absence of Ca(2+), pro-HlyA adopts a non-native conformation. Such molecules could however be rescued by Ca(2+) addition, indicating that these are not dead-end species and that Ca(2+) drives pro-HlyA folding. More importantly, pro-HlyA unfolded via a two-state mechanism, whereas folding was a three-state process. The latter is indicative of the presence of a stable folding intermediate. Analysis of deletion and Trp mutants revealed that the first folding transition, at 6-7M urea, relates to Ca(2+) dependent structural changes at the extreme C-terminus of pro-HlyA, sensed exclusively by Trp914. Since all Trp residues of HlyA are located outside the RTX domain, our results demonstrate that Ca(2+) induced folding is not restricted to the RTX domain. Taken together, Ca(2+) binding to the pro-HlyA RTX domain is required to drive the folding of the entire protein to its native conformation.
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Affiliation(s)
- Sabrina Thomas
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr 1, 40225 Düsseldorf, Germany
| | - Patrick J Bakkes
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr 1, 40225 Düsseldorf, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr 1, 40225 Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr 1, 40225 Düsseldorf, Germany.
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31
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Charge-dependent secretion of an intrinsically disordered protein via the autotransporter pathway. Proc Natl Acad Sci U S A 2013; 110:E4246-55. [PMID: 24145447 DOI: 10.1073/pnas.1310345110] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Autotransporters are a large class of virulence proteins produced by Gram-negative bacteria. They contain an N-terminal extracellular ("passenger") domain that folds into a β-helical structure and a C-terminal β-barrel ("β") domain that anchors the protein to the outer membrane. Because the periplasm lacks ATP, the source of energy that drives passenger domain secretion is unknown. The prevailing model postulates that vectorial folding of the β-helix in the extracellular space facilitates unidirectional secretion of the passenger domain. In this study we used a chimeric protein composed of the 675-residue receptor-binding domain (RD) of the Bordetella pertussis adenylate cyclase toxin CyaA fused to the C terminus of the Escherichia coli O157:H7 autotransporter EspP to test this hypothesis. The RD is a highly acidic, repetitive polypeptide that is intrinsically disordered in the absence of calcium. Surprisingly, we found that the RD moiety was efficiently secreted when it remained in an unfolded conformation. Furthermore, we found that neutralizing or reversing the charge of acidic amino acid clusters stalled translocation in the vicinity of the altered residues. These results challenge the vectorial folding model and, together with the finding that naturally occurring passenger domains are predominantly acidic, provide evidence that a net negative charge plays a significant role in driving the translocation reaction.
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32
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Zhou XR, Ge R, Luo SZ. Self-assembly of pH and calcium dual-responsive peptide-amphiphilic hydrogel. J Pept Sci 2013; 19:737-44. [DOI: 10.1002/psc.2569] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 08/28/2013] [Accepted: 09/02/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Xi-Rui Zhou
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Rui Ge
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Shi-Zhong Luo
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
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A designed, phase changing RTX-based peptide for efficient bioseparations. Biotechniques 2013; 54:197-8, 200, 202, 204, 206. [PMID: 23581466 DOI: 10.2144/000114010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 03/13/2013] [Indexed: 11/23/2022] Open
Abstract
Typically, chromatography is the most costly and time-consuming step in protein purification. As a result, alternative methods have been sought for bioseparations, including the use of stimulus-responsive tags that can reversibly precipitate out of solution in response to the appropriate stimulus. While effective, stimulus-responsive tags tend to require temperature changes or relatively harsh buffer conditions to induce precipitation. Here we describe a synthetic peptide, based on the natural repeat-in-toxin (RTX) domain that undergoes gentler calcium-responsive, reversible precipitation. When coupled to the maltose binding protein (MBP), our calcium-responsive tag efficiently purified the fusion protein. Furthermore, when the MBP was appended to green fluorescent protein (GFP), β-lactamase, or a thermostable alcohol dehydrogenase (AdhD), these constructs could also be purified by calcium-induced precipitation. Finally, protease cleavage of the precipitating tag enables the recovery of pure and active target protein by cycling precipitation before and after cleavage.
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Affiliation(s)
- Scott Banta
- Department of Chemical Engineering, Columbia University, New York, NY 10027;
| | - Kevin Dooley
- Department of Chemical Engineering, Columbia University, New York, NY 10027;
| | - Oren Shur
- Department of Chemical Engineering, Columbia University, New York, NY 10027;
- Current affiliation: Boston Consulting Group, New York, NY 10022
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35
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Shur O, Banta S. Rearranging and concatenating a native RTX domain to understand sequence modularity. Protein Eng Des Sel 2012; 26:171-80. [PMID: 23173179 DOI: 10.1093/protein/gzs092] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The use of repetitive peptide sequences forming predictable secondary structures has been a key paradigm in recent efforts to engineer biomolecular recognition. The modularity and predictability of these scaffolds enables precise identification and mutation of the active interface, providing a level of control which non-repetitive scaffolds often lack. However, the majority of these scaffolds are well-folded stable structures. If the structures had a stimulus-responsive character, this would enable the allosteric regulation of their function. The calcium-responsive beta roll-forming repeats in toxin (RTX) domain potentially offer both of these properties. To further develop this scaffold, we synthesized a set of RTX peptides ranging in size from 5 to 17 repeats, with and without C-terminal capping. We found that while the number of repeats can be altered to tune the size of the RTX face, repeat ordering and C-terminal capping are critical for successful folding. Comparing all of the constructs, we also observed that native configuration with nine repeats exhibited the highest affinity for calcium. In addition, we performed a comparison on a set of known RTX-containing proteins and find that C-terminal repeats often possess deviations from the consensus RTX sequence which may be essential for proper folding. We further find that there seems to be a narrow size range in which RTX domains exist. These results demonstrate that the deviations from the consensus RTX sequence that are observed in natural proteins are important for high-affinity calcium binding and folding. Therefore, the RTX scaffolds will be less modular as compared with other, non-responsive scaffolds, and the sequence-dependent interactions between different repeats will need to be retained in these scaffolds as they are developed in future protein-engineering efforts.
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Affiliation(s)
- Oren Shur
- Department of Chemical Engineering, Columbia University in the City of New York, New York, NY 10027, USA
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36
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Blocquel D, Habchi J, Costanzo S, Doizy A, Oglesbee M, Longhi S. Interaction between the C-terminal domains of measles virus nucleoprotein and phosphoprotein: a tight complex implying one binding site. Protein Sci 2012; 21:1577-85. [PMID: 22887965 DOI: 10.1002/pro.2138] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/27/2012] [Accepted: 07/17/2012] [Indexed: 11/09/2022]
Abstract
The intrinsically disordered C-terminal domain (N(TAIL) ) of the measles virus (MeV) nucleoprotein undergoes α-helical folding upon binding to the C-terminal X domain (XD) of the phosphoprotein. The N(TAIL) region involved in binding coupled to folding has been mapped to a conserved region (Box2) encompassing residues 489-506. In the previous studies published in this journal, we obtained experimental evidence supporting a K(D) for the N(TAIL) -XD binding reaction in the nM range and also showed that an additional N(TAIL) region (Box3, aa 517-525) plays a role in binding to XD. In striking contrast with these data, studies published in this journal by Kingston and coworkers pointed out a much less stable complex (K(D) in the μM range) and supported lack of involvement of Box3 in complex formation. The objective of this study was to critically re-evaluate the role of Box3 in N(TAIL) -XD binding. Since our previous studies relied on N(TAIL) -truncated forms possessing an irrelevant Flag sequence appended at their C-terminus, we, herein, generated an N(TAIL) devoid of Box3 and any additional C-terminal residues, as well as a form encompassing only residues 482-525. We then used isothermal titration calorimetry to characterize the binding reactions between XD and these N(TAIL) forms. Results effectively argue for the presence of a single XD-binding site located within Box2, in agreement with the results by Kingston et al., while providing clear experimental support for a high-affinity complex. Altogether, the present data provide mechanistic insights into the replicative machinery of MeV and clarify a hitherto highly debated point.
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Affiliation(s)
- David Blocquel
- CNRS, Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques (AFMB) UMR 7257, 13288 Marseille, France
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Park Y, Moon Y, Ryoo J, Kim N, Cho H, Ahn JH. Identification of the minimal region in lipase ABC transporter recognition domain of Pseudomonas fluorescens for secretion and fluorescence of green fluorescent protein. Microb Cell Fact 2012; 11:60. [PMID: 22578275 PMCID: PMC3430570 DOI: 10.1186/1475-2859-11-60] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 04/11/2012] [Indexed: 11/22/2022] Open
Abstract
Background TliA is a thermostable lipase secreted by the type 1 secretion system (T1SS) of Pseudomonas fluorescens. The secretion is promoted by its secretion/chaperone domain located near the C-terminus, which is composed mainly of four Repeat-in-Toxin (RTX) repeats. In order to identify the minimal region of TliA responsible for its secretion, five different copies of the secretion/chaperone domain, each involving truncated N-terminal residues and a common C-terminus, were acquired and named as lipase ABC transporter recognition domains (LARDs). Each LARD was fused to epidermal growth factor (EGF) or green fluorescent protein (GFP), and the secretion of EGF-LARD or GFP-LARD fusion proteins was assessed in Escherichia coli with ABC transporter. Results Among the fusion proteins, GFP or EGF with 105-residue LARD3 was most efficiently secreted. In addition, GFP-LARD3 emitted wild type GFP fluorescence. Structurally, LARD3 had the 4 RTX repeats exposed at the N-terminus, while other LARDs had additional residues prior to them or missed some of the RTX repeats. LARD3 was both necessary and sufficient for efficient secretion and maintenance of GFP fluorescence in E. coli, which was also confirmed in P. fluorescens and P. fluorescens ▵tliA, a knock-out mutant of tliA. Conclusion LARD3 was a potent secretion signal in T1SS for its fusion flanking RTX motif, which enhanced secretion and preserved the fluorescence of GFP. LARD3-mediated secretion in E. coli or P. fluorescens will enable the development of enhanced protein manufacturing factory and recombinant microbe secreting protein of interest in situ.
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Affiliation(s)
- Yeonwoo Park
- Korea Science Academy of KAIST, 899 Tanggam 3-Dong, Busanjin-Gu, Busan, 614-822, Korea
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38
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Dooley K, Kim YH, Lu HD, Tu R, Banta S. Engineering of an environmentally responsive beta roll peptide for use as a calcium-dependent cross-linking domain for peptide hydrogel formation. Biomacromolecules 2012; 13:1758-64. [PMID: 22545587 DOI: 10.1021/bm3002446] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have created a set of rationally designed peptides that form calcium-dependent hydrogels based on the beta roll peptide domain. In the absence of calcium, the beta roll domain is intrinsically disordered. Upon the addition of calcium, the peptide forms a beta helix secondary structure. We have designed two variations of our beta roll domain. First, we have mutated one face of the beta roll domain to contain leucine residues so that the calcium-dependent structural formation leads to dimerization through hydrophobic interactions. Second, an α-helical leucine zipper domain is appended to the engineered beta roll domain as an additional means of forming intermolecular cross-links. This full peptide construct forms a hydrogel only in calcium-rich environments. The resulting structural and mechanical properties of the supramolecular assemblies are compared with the wild-type domain using several biophysical techniques including circular dichroism, FRET, bis-ANS binding and microrheology. The calcium responsiveness and rheological properties of the leucine beta roll containing construct confirm the potential of this allosterically regulated scaffold to serve as a cross-linking domain for stimulus-responsive biomaterials development.
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Affiliation(s)
- Kevin Dooley
- Department of Chemical Engineering, Columbia University, New York, New York, United States
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39
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Lotti M, Longhi S. Mutual effects of disorder and order in fusion proteins between intrinsically disordered domains and fluorescent proteins. ACTA ACUST UNITED AC 2012; 8:105-13. [DOI: 10.1039/c1mb05244f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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40
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Shur O, Wu J, Cropek DM, Banta S. Monitoring the conformational changes of an intrinsically disordered peptide using a quartz crystal microbalance. Protein Sci 2011; 20:925-30. [PMID: 21416544 DOI: 10.1002/pro.625] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/04/2011] [Accepted: 03/07/2011] [Indexed: 11/05/2022]
Abstract
Intrinsically disordered peptides (IDPs) have recently garnered much interest because of their role in biological processes such as molecular recognition and their ability to undergo stimulus-responsive conformational changes. The block V repeat-in-toxin motif of the Bordetella pertussis adenylate cyclase is an example of an IDP that undergoes a transition from a disordered state to an ordered beta roll conformation in the presence of calcium ions. In solution, a C-terminal capping domain is necessary for this transition to occur. To further explore the conformational behavior and folding requirements of this IDP, we have cysteine modified three previously characterized constructs, allowing for attachment to the gold surface of a quartz crystal microbalance (QCM). We demonstrate that, while immobilized, the C-terminally capped peptide exhibits similar calcium-binding properties to what have been observed in solution. In addition, immobilization on the solid surface appears to enable calcium-responsiveness in the uncapped peptides, in contrast to the behavior observed in solution. This work demonstrates the power of QCM as a tool to study the conformational changes of IDPs immobilized on surfaces and has implications for a range of potential applications where IDPs may be engineered and used including protein purification, biosensors, and other bionanotechnology applications.
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Affiliation(s)
- Oren Shur
- Department of Chemical Engineering, Columbia University, New York, New York, USA
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41
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Sotomayor-Pérez AC, Ladant D, Chenal A. Calcium-induced folding of intrinsically disordered repeat-in-toxin (RTX) motifs via changes of protein charges and oligomerization states. J Biol Chem 2011; 286:16997-7004. [PMID: 21454565 DOI: 10.1074/jbc.m110.210393] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by so-called RTX (repeat-in-toxin) motifs found in many virulence factors secreted by numerous gram-negative pathogenic bacteria: RTX proteins are natively disordered in the absence of calcium but fold upon calcium binding. The adenylate cyclase toxin (CyaA) produced by Bordetella pertussis, the causative agent of whooping cough, contains ∼40 RTX motifs organized in five successive blocks separated by non-RTX flanking regions. This RTX domain mediates toxin binding to its eukaryotic cell receptor. We previously showed that the last block of the RTX domain, block V, which is critical for CyaA toxicity, exhibits the hallmarks of intrinsically disordered proteins in the absence of calcium. Moreover, the C-terminal flanking region of CyaA block V is required for its calcium-induced folding. Here, we describe a comprehensive analysis of the hydrodynamic and electrophoretic properties of several block V RTX polypeptides that differ in the presence and/or length of the flanking regions. Our results indicate that the length of the C-terminal flanking region not only controls the calcium-induced folding but also the calcium-induced multimerization of the RTX polypeptides. Moreover, we showed that calcium binding is accompanied by a strong reduction of the net charge of the RTX polypeptides. These data indicate that the disorder-to-order transition in RTX proteins is controlled by a calcium-induced change of the polypeptide charges and stabilized by multimerization.
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Affiliation(s)
- Ana Cristina Sotomayor-Pérez
- Institut Pasteur, CNRS URA 2185, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, 75724 Paris Cedex 15, France
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42
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Frunzi M, Baldwin AM, Shibata N, Iwamatsu SI, Lawler RG, Turro NJ. Kinetics and Solvent-Dependent Thermodynamics of Water Capture by a Fullerene-Based Hydrophobic Nanocavity. J Phys Chem A 2011; 115:735-40. [DOI: 10.1021/jp110832m] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Frunzi
- Department of Chemistry, Columbia University, New York, New York 10027, United States of America
| | - Anne M. Baldwin
- Department of Chemistry, Columbia University, New York, New York 10027, United States of America
| | - Nobuyuki Shibata
- Graduate School of Environmental Studies, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Sho-Ichi Iwamatsu
- Graduate School of Environmental Studies, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Ronald G. Lawler
- Department of Chemistry, Brown University, Providence, Rhode Island 02912-9108, United States of America
| | - Nicholas J. Turro
- Department of Chemistry, Columbia University, New York, New York 10027, United States of America
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43
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Banta S, Wheeldon IR, Blenner M. Protein Engineering in the Development of Functional Hydrogels. Annu Rev Biomed Eng 2010; 12:167-86. [PMID: 20420519 DOI: 10.1146/annurev-bioeng-070909-105334] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York 10027;
| | - Ian R. Wheeldon
- Department of Chemical Engineering, Columbia University, New York, New York 10027;
| | - Mark Blenner
- Current address: Department of Medicine, Center for Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115;
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