1
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Romero‐Casañas A, García‐Lizarribar A, Castro J, Vilanova M, Benito A, Ribó M. Ligation of multiple protein domains using orthogonal inteins with non-native splice junctions. Protein Sci 2024; 33:e5070. [PMID: 38864750 PMCID: PMC11168065 DOI: 10.1002/pro.5070] [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: 10/06/2023] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/13/2024]
Abstract
Protein splicing is a self-catalyzed process in which an internal protein domain (the intein) is excised from its flanking sequences, linking them together with a canonical peptide bond. Trans-inteins are separated in two different precursor polypeptide chains that must assemble to catalytically self-excise and ligate the corresponding flanking exteins to join even when expressed separately either in vitro or in vivo. They are very interesting to construct full proteins from separate domains because their common small size favors chemical synthesis approaches. Therefore, trans-inteins have multiple applications such as protein modification and purification, structural characterization of protein domains or production of intein-based biosensors, among others. For many of these applications, when using more than one trans-intein, orthogonality between them is a critical issue to ensure the proper ligation of the exteins. Here, we confirm the orthogonality (lack of cross-reactivity) of four different trans- or split inteins, gp41-1, gp41-8, IMPDH-1 and NrdJ-1 both in vivo and in vitro, and built different constructs that allow for the sequential fusion of up to four protein fragments into one final spliced product. We have characterized the splicing efficiency of these constructs. All harbor non-native extein residues at the splice junction between the trans-intein and the neighboring exteins, except for the essential Ser + 1. Our results show that it is possible to ligate four different protein domains using inteins gp41-1, IMPDH-1 and NrdJ-1 with non-native extein residues to obtain a final four-domain spliced product with a not negligible yield that keeps its native sequence.
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Affiliation(s)
| | | | - Jessica Castro
- Laboratori d'Enginyeria de Proteïnes, Departament de BiologiaUniversitat de GironaGironaSpain
- Institut d'Investigació Biomèdica de Girona Josep Trueta (IdIBGi)SaltSpain
| | - Maria Vilanova
- Laboratori d'Enginyeria de Proteïnes, Departament de BiologiaUniversitat de GironaGironaSpain
- Institut d'Investigació Biomèdica de Girona Josep Trueta (IdIBGi)SaltSpain
| | - Antoni Benito
- Laboratori d'Enginyeria de Proteïnes, Departament de BiologiaUniversitat de GironaGironaSpain
- Institut d'Investigació Biomèdica de Girona Josep Trueta (IdIBGi)SaltSpain
| | - Marc Ribó
- Laboratori d'Enginyeria de Proteïnes, Departament de BiologiaUniversitat de GironaGironaSpain
- Institut d'Investigació Biomèdica de Girona Josep Trueta (IdIBGi)SaltSpain
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2
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Diptiman D, Jalan A, Pal R, Dodwani S, Bandyopadhyay D. Hist-i-fy-a multiple histidine post-translational-modification (PTM) prediction server based on protein sequences using convolution neural network: a case study on mass spectroscopy data. J Biomol Struct Dyn 2024:1-10. [PMID: 38285683 DOI: 10.1080/07391102.2024.2310200] [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: 07/24/2023] [Accepted: 01/19/2024] [Indexed: 01/31/2024]
Abstract
Computational characterization of multiple Histidine (His) post-translational-modifications (PTM) at enzyme active sites complements tedious experimental characterization in proteins-of-unknown-functions (PUFs) and domain-of-unknown-functions (DUFs). There are only a handful of Histidine-PTM-prediction-tools and those also annotate only a single function. Here, we addressed the problem using artificial neural networks on functional histidine dataset curated from enzyme (protein) sequences available in UniProt database (sample size n = 1584). The convolution-neural-network (CNN) model ('Hist-i-fy') performed the best with 75% overall accuracy/F1-score. A case study was performed on histidine-phosphorylation (n = 34) obtained from mass spectroscopy data. For the first time, we report multiple His-PTM-prediction-tool (https://histify.streamlit.app/& https://github.com/dibyansu24-maker/Histify), with optimal performance. The inputs to the tool are (i) protein sequence containing histidine, and (ii) the histidine residue number. Prediction output is one out of the eight histidine functions-acetylation, ribosylation, glycosylation, hydroxylation, methylation, oxidation, phosphorylation, and protein splicing.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Dibyansu Diptiman
- Department of Biological Sciences, Birla Institute of Technology and Science, Hyderabad, India
| | - Abhishek Jalan
- Department of Biological Sciences, Birla Institute of Technology and Science, Hyderabad, India
| | - Rishabh Pal
- Department of Biological Sciences, Birla Institute of Technology and Science, Hyderabad, India
| | - Sachin Dodwani
- Department of Biological Sciences, Birla Institute of Technology and Science, Hyderabad, India
| | - Debashree Bandyopadhyay
- Department of Biological Sciences, Birla Institute of Technology and Science, Hyderabad, India
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3
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Boral S, Sen S, Kushwaha T, Inampudi KK, De S. Extein residues regulate the catalytic function of Spl DnaX intein enzyme by restricting the near-attack conformations of the active-site residues. Protein Sci 2023; 32:e4699. [PMID: 37313648 PMCID: PMC10288555 DOI: 10.1002/pro.4699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023]
Abstract
Intein enzymes catalyze the splicing of their flanking polypeptide chains and have found tremendous biotechnological applications. Their terminal residues form the catalytic core and participate in the splicing reaction. Hence, the neighboring N- and C-terminal extein residues influence the catalytic rate. As these extein residues vary depending on the substrate identity, we tested the influence of 20 amino acids at these sites in the Spl DnaX intein and observed significant variation of spliced product as well as N- and C-terminus cleavage product formation. We investigated the dependence of these reactions on the extein residues by molecular dynamics (MD) simulations on eight extein variants, and found that the conformational sampling of the active-site residues of the intein enzyme differed among these extein variants. We found that the extein variants that sample higher population of near-attack conformers (NACs) of the active-site residues undergo higher product formation in our activity assays. Ground state conformers that closely resemble the transition state are referred to as NACs. Very good correlation was observed between the NAC populations from the MD simulations of eight extein variants and the corresponding product formation from our activity assays. Furthermore, this molecular detail enabled us to elucidate the mechanistic roles of several conserved active-site residues in the splicing reaction. Overall, this study shows that the catalytic power of Spl DnaX intein enzyme, and most likely other inteins, depends on the efficiency of formation of NACs in the ground state, which is further modulated by the extein residues.
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Affiliation(s)
- Soumendu Boral
- School of BioscienceIndian Institute of Technology KharagpurKharagpurIndia
| | - Srijon Sen
- School of BioscienceIndian Institute of Technology KharagpurKharagpurIndia
| | - Tushar Kushwaha
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Krishna K. Inampudi
- Department of BiophysicsAll India Institute of Medical SciencesNew DelhiIndia
| | - Soumya De
- School of BioscienceIndian Institute of Technology KharagpurKharagpurIndia
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4
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Pasch T, Schröder A, Kattelmann S, Eisenstein M, Pietrokovski S, Kümmel D, Mootz HD. Structural and biochemical analysis of a novel atypically split intein reveals a conserved histidine specific to cysteine-less inteins. Chem Sci 2023; 14:5204-5213. [PMID: 37206380 PMCID: PMC10189870 DOI: 10.1039/d3sc01200j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 04/23/2023] [Indexed: 05/21/2023] Open
Abstract
Protein trans-splicing mediated by a split intein reconstitutes a protein backbone from two parts. This virtually traceless autoprocessive reaction provides the basis for numerous protein engineering applications. Protein splicing typically proceeds through two thioester or oxyester intermediates involving the side chains of cysteine or serine/threonine residues. A cysteine-less split intein has recently attracted particular interest as it can splice under oxidizing conditions and is orthogonal to disulfide or thiol bioconjugation chemistries. Here, we report the split PolB16 OarG intein, a second such cysteine-independent intein. As a unique trait, it is atypically split with a short intein-N precursor fragment of only 15 amino acids, the shortest characterized to date, which was chemically synthesized to enable protein semi-synthesis. By rational engineering we obtained a high-yielding, improved split intein mutant. Structural and mutational analysis revealed the dispensability of the usually crucial conserved motif N3 (block B) histidine as an obvious peculiar property. Unexpectedly, we identified a previously unnoticed histidine in hydrogen-bond forming distance to the catalytic serine 1 as critical for splicing. This histidine has been overlooked so far in multiple sequence alignments and is highly conserved only in cysteine-independent inteins as a part of a newly discovered motif NX. The motif NX histidine is thus likely of general importance to the specialized environment in the active site required in this intein subgroup. Together, our study advances the toolbox as well as the structural and mechanistic understanding of cysteine-less inteins.
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Affiliation(s)
- Tim Pasch
- Institute of Biochemistry, University of Münster Corrensstr. 36 48149 Münster Germany
| | - Alexander Schröder
- Institute of Biochemistry, University of Münster Corrensstr. 36 48149 Münster Germany
| | - Sabrina Kattelmann
- Institute of Biochemistry, University of Münster Corrensstr. 36 48149 Münster Germany
| | - Miriam Eisenstein
- Department of Molecular Genetics, Weizmann Institute of Science Rehovot 76100 Israel
| | - Shmuel Pietrokovski
- Department of Molecular Genetics, Weizmann Institute of Science Rehovot 76100 Israel
| | - Daniel Kümmel
- Institute of Biochemistry, University of Münster Corrensstr. 36 48149 Münster Germany
| | - Henning D Mootz
- Institute of Biochemistry, University of Münster Corrensstr. 36 48149 Münster Germany
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5
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Sekar G, Stevens AJ, Mostafavi AZ, Sashi P, Muir TW, Cowburn D. A Conserved Histidine Residue Drives Extein Dependence in an Enhanced Atypically Split Intein. J Am Chem Soc 2022; 144:19196-19203. [PMID: 36194550 PMCID: PMC10241006 DOI: 10.1021/jacs.2c08985] [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] [Indexed: 11/30/2022]
Abstract
Split intein-mediated protein trans-splicing (PTS) is widely applied in chemical biology and biotechnology to carry out traceless and specific protein ligation. However, the external residues immediately flanking the intein (exteins) can reduce the splicing rate, thereby limiting certain applications of PTS. Splicing by a recently developed intein with atypical split architecture ("Cat") exhibits a stark dependence on the sequence of its N-terminal extein residues. Here, we further developed Cat using error-prone polymerase chain reaction (PCR) and a cell-based selection assay to produce Cat*, which exhibits greatly enhanced PTS activity in the presence of unfavorable N-extein residues. We then applied solution nuclear magnetic resonance spectroscopy and molecular dynamics simulations to explore how the dynamics of a conserved B-block histidine residue (His78) contribute to this extein dependence. The enhanced extein tolerance of Cat* reported here should expand the applicability of atypically split inteins, and the mechanism highlights common principles that contribute to extein dependence.
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Affiliation(s)
- Giridhar Sekar
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Adam J. Stevens
- Department of Chemistry, Princeton University, Frick Laboratory, Princeton, New Jersey 08544, USA
| | - Anahita Z. Mostafavi
- Department of Chemistry, Princeton University, Frick Laboratory, Princeton, New Jersey 08544, USA
| | - Pulikallu Sashi
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Tom W. Muir
- Department of Chemistry, Princeton University, Frick Laboratory, Princeton, New Jersey 08544, USA
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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6
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SufB intein splicing in Mycobacterium tuberculosis is influenced by two remote conserved N-extein histidines. Biosci Rep 2022; 42:230724. [PMID: 35234249 PMCID: PMC8891592 DOI: 10.1042/bsr20212207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 01/11/2022] [Accepted: 01/27/2022] [Indexed: 11/24/2022] Open
Abstract
Inteins are auto-processing domains that implement a multistep biochemical reaction termed protein splicing, marked by cleavage and formation of peptide bonds. They excise from a precursor protein, generating a functional protein via covalent bonding of flanking exteins. We report the kinetic study of splicing and cleavage reaction in [Fe–S] cluster assembly protein SufB from Mycobacterium tuberculosis (Mtu). Although it follows a canonical intein splicing pathway, distinct features are added by extein residues present in the active site. Sequence analysis identified two conserved histidines in the N-extein region; His-5 and His-38. Kinetic analyses of His-5Ala and His-38Ala SufB mutants exhibited significant reductions in splicing and cleavage rates relative to the SufB wildtype (WT) precursor protein. Structural analysis and molecular dynamics (MD) simulations suggested that Mtu SufB displays a unique mechanism where two remote histidines work concurrently to facilitate N-terminal cleavage reaction. His-38 is stabilized by the solvent-exposed His-5, and can impact N–S acyl shift by direct interaction with the catalytic Cys1. Development of inteins as biotechnological tools or as pathogen-specific novel antimicrobial targets requires a more complete understanding of such unexpected roles of conserved extein residues in protein splicing.
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7
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Nanda A, Nasker SS, Kushwaha AK, Ojha DK, Dearden AK, Nayak SK, Nayak S. Gold Nanoparticles Augment N-Terminal Cleavage and Splicing Reactions in Mycobacterium tuberculosis SufB. Front Bioeng Biotechnol 2021; 9:773303. [PMID: 35004641 PMCID: PMC8735848 DOI: 10.3389/fbioe.2021.773303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/12/2021] [Indexed: 11/13/2022] Open
Abstract
Protein splicing is a self-catalyzed event where the intervening sequence intein cleaves off, joining the flanking exteins together to generate a functional protein. Attempts have been made to regulate the splicing rate through variations in temperature, pH, and metals. Although metal-regulated protein splicing has been more captivating to researchers, metals were shown to only inhibit splicing reactions that confine their application. This is the first study to show the effect of nanoparticles (NPs) on protein splicing. We found that gold nanoparticles (AuNPs) of various sizes can increase the splicing efficiency by more than 50% and the N-terminal cleavage efficiency by more than 45% in Mycobacterium tuberculosis SufB precursor protein. This study provides an effective strategy for engineering splicing-enhanced intein platforms. UV-vis absorption spectroscopy, isothermal titration calorimetry (ITC), and transmission electron microscopy (TEM) confirmed AuNP interaction with the native protein. Quantum mechanics/molecular mechanics (QM/MM) analysis suggested a significant reduction in the energy barrier at the N-terminal cleavage site in the presence of gold atom, strengthening our experimental evidence on heightened the N-terminal cleavage reaction. The encouraging observation of enhanced N-terminal cleavage and splicing reaction can have potential implementations from developing a rapid drug delivery system to designing a contemporary protein purification system.
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Affiliation(s)
- Ananya Nanda
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, India
| | - Sourya Subhra Nasker
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, India
| | - Anoop K. Kushwaha
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
| | - Deepak Kumar Ojha
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, India
| | - Albert K. Dearden
- Departments of Physics and Astronomy, College of Arts and Sciences, University of South Carolina, Columbia, SC, United States
| | - Saroj K. Nayak
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
| | - Sasmita Nayak
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, India
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8
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Panda S, Nanda A, Nasker SS, Sen D, Mehra A, Nayak S. Metal effect on intein splicing: A review. Biochimie 2021; 185:53-67. [PMID: 33727137 DOI: 10.1016/j.biochi.2021.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 02/08/2023]
Abstract
Inteins are intervening polypeptides that interrupt the functional domains of several important proteins across the three domains of life. Inteins excise themselves from the precursor protein, ligating concomitant extein residues in a process called protein splicing. Post-translational auto-removal of inteins remain critical for the generation of active proteins. The perspective of inteins in science is a robust field of research, however fundamental studies centralized upon splicing regulatory mechanism are imperative for addressing more intricate issues. Controlled engineering of intein splicing has many applications; intein inhibition can facilitate novel drug design, while activation of intein splicing is exploited in protein purification. This paper provides a comprehensive review of the past and recent advances in the splicing regulation via metal-intein interaction. We compare the behavior of different metal ions on diverse intein systems. Though metals such as Zn, Cu, Pt, Cd, Co, Ni exhibit intein inhibitory effect heterogeneously on different inteins, divalent metal ions such as Ca and Mg fail to do so. The observed diversity in the metal-intein interaction arises mostly due to intein polymorphism and variations in atomic structure of metals. A mechanistic understanding of intein regulation by metals in native as well as synthetically engineered intein systems may yield potent intein inhibitors via direct or indirect approach.
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Affiliation(s)
- Sunita Panda
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Ananya Nanda
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Sourya Subhra Nasker
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Debjani Sen
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Ashwaria Mehra
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India
| | - Sasmita Nayak
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, 751024, India.
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9
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Inteins in Science: Evolution to Application. Microorganisms 2020; 8:microorganisms8122004. [PMID: 33339089 PMCID: PMC7765530 DOI: 10.3390/microorganisms8122004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/20/2022] Open
Abstract
Inteins are mobile genetic elements that apply standard enzymatic strategies to excise themselves post-translationally from the precursor protein via protein splicing. Since their discovery in the 1990s, recent advances in intein technology allow for them to be implemented as a modern biotechnological contrivance. Radical improvement in the structure and catalytic framework of cis- and trans-splicing inteins devised the development of engineered inteins that contribute to various efficient downstream techniques. Previous literature indicates that implementation of intein-mediated splicing has been extended to in vivo systems. Besides, the homing endonuclease domain also acts as a versatile biotechnological tool involving genetic manipulation and control of monogenic diseases. This review orients the understanding of inteins by sequentially studying the distribution and evolution pattern of intein, thereby highlighting a role in genetic mobility. Further, we include an in-depth summary of specific applications branching from protein purification using self-cleaving tags to protein modification, post-translational processing and labelling, followed by the development of intein-based biosensors. These engineered inteins offer a disruptive approach towards research avenues like biomaterial construction, metabolic engineering and synthetic biology. Therefore, this linear perspective allows for a more comprehensive understanding of intein function and its diverse applications.
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10
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Hoffmann S, Terhorst TME, Singh RK, Kümmel D, Pietrokovski S, Mootz HD. Biochemical and Structural Characterization of an Unusual and Naturally Split Class 3 Intein. Chembiochem 2020; 22:364-373. [PMID: 32813312 PMCID: PMC7891396 DOI: 10.1002/cbic.202000509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/19/2020] [Indexed: 12/31/2022]
Abstract
Split inteins are indispensable tools for protein engineering because their ligation and cleavage reactions enable unique modifications of the polypeptide backbone. Three different classes of inteins have been identified according to the nature of the covalent intermediates resulting from the acyl rearrangements in the multistep protein‐splicing pathway. Class 3 inteins employ a characteristic internal cysteine for a branched thioester intermediate. A bioinformatic database search of non‐redundant protein sequences revealed the absence of split variants in 1701 class 3 inteins. We have discovered the first reported split class 3 intein in a metagenomics data set and report its biochemical, mechanistic and structural analysis. The AceL NrdHF intein exhibits low sequence conservation with other inteins and marked deviations in residues at conserved key positions, including a variation of the typical class‐3 WCT triplet motif. Nevertheless, functional analysis confirmed the class 3 mechanism of the intein and revealed excellent splicing yields within a few minutes over a wide range of conditions and with barely detectable cleavage side reactions. A high‐resolution crystal structure of the AceL NrdHF precursor and a mutagenesis study explained the importance and roles of several residues at the key positions. Tolerated substitutions in the flanking extein residues and a high affinity between the split intein fragments further underline the intein's future potential as a ligation tool.
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Affiliation(s)
- Simon Hoffmann
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149, Münster, Germany
| | - Tobias M E Terhorst
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149, Münster, Germany
| | - Rohit K Singh
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149, Münster, Germany
| | - Daniel Kümmel
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149, Münster, Germany
| | - Shmuel Pietrokovski
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Henning D Mootz
- Institute of Biochemistry, University of Muenster, Corrensstraße 36, 48149, Münster, Germany
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11
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Zhao J, Du Z, Wang C, Mills KV. Methods to Study the Structure and Catalytic Activity of cis-Splicing Inteins. Methods Mol Biol 2020; 2133:55-73. [PMID: 32144663 PMCID: PMC7325523 DOI: 10.1007/978-1-0716-0434-2_4] [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] [Indexed: 05/26/2024]
Abstract
The autocatalytic process of protein splicing is facilitated by an intein, which interrupts flanking polypeptides called exteins. The mechanism of protein splicing has been studied by overexpression in E. coli of intein fusion proteins with nonnative exteins. Inteins can be used to generate reactive α-thioesters, as well as proteins with N-terminal Cys residues, to facilitate expressed protein ligation. As such, a more detailed understanding of the function of inteins can have significant impact for biotechnology applications. Here, we provide biochemical methods to study splicing activity and NMR methods to study intein structure and the catalytic mechanism.
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Affiliation(s)
- Jing Zhao
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Zhenming Du
- Department of Chemistry, Georgia State University, Atlanta, GA, USA
| | - Chunyu Wang
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Kenneth V Mills
- Department of Chemistry, College of the Holy Cross, Worcester, MA, USA.
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12
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Zhao J, Ciulla DA, Xie J, Wagner AG, Castillo DA, Zwarycz AS, Lin Z, Beadle S, Giner JL, Li Z, Li H, Banavali N, Callahan BP, Wang C. General Base Swap Preserves Activity and Expands Substrate Tolerance in Hedgehog Autoprocessing. J Am Chem Soc 2019; 141:18380-18384. [PMID: 31682419 PMCID: PMC7106946 DOI: 10.1021/jacs.9b08914] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hedgehog (Hh) autoprocessing converts Hh precursor protein to cholesterylated Hh ligand for downstream signaling. A conserved active-site aspartate residue, D46, plays a key catalytic role in Hh autoprocessing by serving as a general base to activate substrate cholesterol. Here we report that a charge-altering Asp-to-His mutant (D46H) expands native cholesterylation activity and retains active-site conformation. Native activity toward cholesterol was established for D46H in vitro using a continuous FRET-based autoprocessing assay and in cellulo with stable expression in human 293T cells. The catalytic efficiency of cholesterylation with D46H is similar to that with wild type (WT), with kmax/KM = 2.1 × 103 and 3.7 × 103 M-1 s-1, respectively, and an identical pKa = 5.8 is obtained for both residues by NMR. To our knowledge this is the first example where a general base substitution of an Asp for His preserves both the structure and activity as a general base. Surprisingly, D46H exhibits increased catalytic efficiency toward non-native substrates, especially coprostanol (>200-fold) and epicoprostanol (>300-fold). Expanded substrate tolerance is likely due to stabilization by H46 of the negatively charged tetrahedral intermediate using electrostatic interactions, which are less constrained by geometry than H-bond stabilization by D46. In addition to providing fundamental insights into Hh autoprocessing, our findings have important implications for protein engineering and enzyme design.
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Affiliation(s)
- Jing Zhao
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Daniel A. Ciulla
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Jian Xie
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Andrew G. Wagner
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Drew A. Castillo
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Allison S. Zwarycz
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Zhongqian Lin
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Seth Beadle
- Department of Chemistry, State University of New York-ESF, Syracuse, New York 13210, United States
| | - José-Luis Giner
- Department of Chemistry, State University of New York-ESF, Syracuse, New York 13210, United States
| | - Zhong Li
- Wadsworth Center, New York State Department of Health, Albany, New York 12201, United States
| | - Hongmin Li
- Wadsworth Center, New York State Department of Health, Albany, New York 12201, United States
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York 12222, United States
| | - Nilesh Banavali
- Wadsworth Center, New York State Department of Health, Albany, New York 12201, United States
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York 12222, United States
| | - Brian P. Callahan
- Department of Chemistry, Binghamton University, State University of New York, Binghamton, New York 13902, United States
| | - Chunyu Wang
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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13
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Lin Z, Zhao Q, Wang X, Zhou B, Xing L, Wang J, Pistolozzi M, Zhao L, Wang T. Engineered pH‐inducible intein
Mtu
ΔI‐CM variants with markedly reduced premature cleavage activity. AIChE J 2019. [DOI: 10.1002/aic.16806] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Zhanglin Lin
- School of Biology and Biological EngineeringSouth China University of Technology Guangzhou China
- Department of Chemical EngineeringTsinghua University Beijing China
| | - Qing Zhao
- Department of Chemical EngineeringTsinghua University Beijing China
| | - Xu Wang
- Department of Chemical EngineeringTsinghua University Beijing China
| | - Bihong Zhou
- Department of Chemical EngineeringTsinghua University Beijing China
| | - Lei Xing
- Department of Chemical EngineeringTsinghua University Beijing China
| | - Jiangyun Wang
- Institute of BiophysicsChinese Academy of Sciences Beijing China
| | - Marco Pistolozzi
- School of Biology and Biological EngineeringSouth China University of Technology Guangzhou China
| | - Lei Zhao
- School of Biology and Biological EngineeringSouth China University of Technology Guangzhou China
| | - Tingting Wang
- School of Biology and Biological EngineeringSouth China University of Technology Guangzhou China
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14
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Shi Y, Hong X, Fan H, Wu Z, Liu A. Characterizing Novel Modifications of a Therapeutic Protein Using Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry, Sedimentation Velocity Analytical Ultracentrifugation, and Structural Modeling. Anal Chem 2018; 90:12870-12877. [PMID: 30295031 DOI: 10.1021/acs.analchem.8b03459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heterogeneity of biopharmaceutical products is common due to various co- and post-translational modifications and degradation events that occur during the biological production process and throughout the shelf life. Product-related variants resulting from these modifications potentially affect a product's biological activity and safety, and thus, their detailed structure characterization is of great importance for successful development of protein therapeutics. Specifically, in this study, two novel low-level product variants in a recombinant therapeutic protein were characterized via chromatographic enrichment followed by proteolytic digestion and analysis using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). One of the variants was identified to be the therapeutic protein missing a 61-amino-acid fragment from its N-terminus. Consequently, the other variant was found to be the therapeutic protein carrying the 61-amino-acid long peptide. Furthermore, detailed structure at the modification site of the latter variant was determined as that amino group from the protein's N-terminus linked to side chain carbonyl carbon at Asp 61 residue of the peptide, based on the complementary information from collision induced dissociation and electron transfer dissociation MS/MS analysis. Results from sedimentation velocity analytical ultracentrifugation and computational structural modeling supported the hypothesis that formation of these two variants was a result of protein self-association. In dimeric state, the head-to-toe stacking conformation of two therapeutic protein molecules allowed spatial closeness between the N-terminus of one molecule and the 61st amino acid of the other molecule, resulting in a novel peptide transfer between the two protein molecules.
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15
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Friedel K, Popp MA, Matern JCJ, Gazdag EM, Thiel IV, Volkmann G, Blankenfeldt W, Mootz HD. A functional interplay between intein and extein sequences in protein splicing compensates for the essential block B histidine. Chem Sci 2018; 10:239-251. [PMID: 30713635 PMCID: PMC6333167 DOI: 10.1039/c8sc01074a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/03/2018] [Indexed: 01/28/2023] Open
Abstract
Steric bulk can compensate for a catalytically critical histidine in an intein's active site and promote the N–S acyl shift.
Inteins remove themselves from a precursor protein by protein splicing. Due to the concomitant structural changes of the host protein, this self-processing reaction has enabled many applications in protein biotechnology and chemical biology. We show that the evolved M86 mutant of the Ssp DnaB intein displays a significantly improved tolerance towards non-native amino acids at the N-terminally flanking (–1) extein position compared to the parent intein, in the form of both an artificially trans-splicing split intein and the cis-splicing mini-intein. Surprisingly, side chains with increased steric bulk compared to the native Gly(–1) residue, including d-amino acids, were found to compensate for the essential block B histidine in His73Ala mutants in the initial N–S acyl shift of the protein splicing pathway. In the case of the M86 intein, large (–1) side chains can even rescue protein splicing activity as a whole. With the comparison of three crystal structures, namely of the M86 intein as well as of its Gly(–1)Phe and Gly(–1)Phe/His73Ala mutants, our data supports a model in which the intein's active site can exert a strain by varying mechanisms on the different angles of the scissile bond at the extein–intein junction to effect a ground-state destabilization. The compensatory mechanism of the block B histidine is the first example for the direct functional role of an extein residue in protein splicing. It sheds new light on the extein–intein interplay and on possible consequences of their co-evolution as well as on the laboratory engineering of improved inteins.
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Affiliation(s)
- Kristina Friedel
- Institute of Biochemistry , University of Muenster , Wilhelm-Klemm-Str. 2 , 48149 Münster , Germany .
| | - Monika A Popp
- Structure and Function of Proteins , Helmholtz Centre for Infection Research , Inhoffenstraße 7 , 38124 , Braunschweig , Germany
| | - Julian C J Matern
- Institute of Biochemistry , University of Muenster , Wilhelm-Klemm-Str. 2 , 48149 Münster , Germany .
| | - Emerich M Gazdag
- Structure and Function of Proteins , Helmholtz Centre for Infection Research , Inhoffenstraße 7 , 38124 , Braunschweig , Germany
| | - Ilka V Thiel
- Institute of Biochemistry , University of Muenster , Wilhelm-Klemm-Str. 2 , 48149 Münster , Germany .
| | - Gerrit Volkmann
- Institute of Biochemistry , University of Muenster , Wilhelm-Klemm-Str. 2 , 48149 Münster , Germany .
| | - Wulf Blankenfeldt
- Structure and Function of Proteins , Helmholtz Centre for Infection Research , Inhoffenstraße 7 , 38124 , Braunschweig , Germany.,Institute for Biochemistry, Biotechnology and Bioinformatics , Technische Universität Braunschweig , Spielmannstraße 7 , 38106 Braunschweig , Germany
| | - Henning D Mootz
- Institute of Biochemistry , University of Muenster , Wilhelm-Klemm-Str. 2 , 48149 Münster , Germany .
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16
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Gordo V, Aparicio D, Pérez-Luque R, Benito A, Vilanova M, Usón I, Fita I, Ribó M. Structural Insights into Subunits Assembly and the Oxyester Splicing Mechanism of Neq pol Split Intein. Cell Chem Biol 2018; 25:871-879.e2. [PMID: 29754955 DOI: 10.1016/j.chembiol.2018.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/28/2018] [Accepted: 04/08/2018] [Indexed: 11/28/2022]
Abstract
Split inteins are expressed as two separated subunits (N-intein and C-intein) fused to the corresponding exteins. The specific association of both intein subunits precedes protein splicing, which results in excision of the intein subunits and in ligation, by a peptide bond, of the concomitant exteins. Catalytically active intein precursors are typically too reactive for crystallization or even isolation. Neq pol is the trans-intein of the B-type DNA polymerase I split gene from hyperthermophile Nanoarchaeum equitans. We have determined the crystal structures of both the isolated NeqN and the complex of NeqN and NeqC subunits carrying the wild-type sequences, including the essential catalytic residues Ser1 and Thr+1, in addition to seven and three residues of the N- and C-exteins, respectively. These structures provide detailed information on the unique oxyester chemistry of the splicing mechanism of Neq pol and of the extensive rearrangements that occur in NeqN during the association step.
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Affiliation(s)
- Verónica Gordo
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 40, 17003 Girona, Spain; IdIBGi Hospital Universitari Josep Trueta, Girona, Spain
| | - David Aparicio
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Cientific de Barcelona, Baldiri i Reixac 10, 08028 Barcelona, Spain
| | - Rosa Pérez-Luque
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Cientific de Barcelona, Baldiri i Reixac 10, 08028 Barcelona, Spain
| | - Antoni Benito
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 40, 17003 Girona, Spain; IdIBGi Hospital Universitari Josep Trueta, Girona, Spain
| | - Maria Vilanova
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 40, 17003 Girona, Spain; IdIBGi Hospital Universitari Josep Trueta, Girona, Spain
| | - Isabel Usón
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Cientific de Barcelona, Baldiri i Reixac 10, 08028 Barcelona, Spain; ICREA Lluís Companys 23, 08003 Barcelona, Spain
| | - Ignacio Fita
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Cientific de Barcelona, Baldiri i Reixac 10, 08028 Barcelona, Spain.
| | - Marc Ribó
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 40, 17003 Girona, Spain; IdIBGi Hospital Universitari Josep Trueta, Girona, Spain.
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17
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Kick LM, Harteis S, Koch MF, Schneider S. Mechanistic Insights into Cyclic Peptide Generation by DnaE Split-Inteins through Quantitative and Structural Investigation. Chembiochem 2017; 18:2242-2246. [DOI: 10.1002/cbic.201700503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Leonhard M. Kick
- Center for Integrated Protein Science; Department of Chemistry; Technische Universität München; Lichtenbergstrasse 4 85748 Garching Germany
| | - Sabrina Harteis
- Center for Integrated Protein Science; Department of Chemistry; Technische Universität München; Lichtenbergstrasse 4 85748 Garching Germany
| | - Maximilian F. Koch
- Center for Integrated Protein Science; Department of Chemistry; Technische Universität München; Lichtenbergstrasse 4 85748 Garching Germany
| | - Sabine Schneider
- Center for Integrated Protein Science; Department of Chemistry; Technische Universität München; Lichtenbergstrasse 4 85748 Garching Germany
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18
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Mujika JI, Lopez X. Unveiling the Catalytic Role of B-Block Histidine in the N–S Acyl Shift Step of Protein Splicing. J Phys Chem B 2017; 121:7786-7796. [DOI: 10.1021/acs.jpcb.7b04276] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. I. Mujika
- Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Euskadi Spain
| | - X. Lopez
- Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Euskadi Spain
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19
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Burke HM, McSweeney L, Scanlan EM. Exploring chemoselective S-to-N acyl transfer reactions in synthesis and chemical biology. Nat Commun 2017; 8:15655. [PMID: 28537277 PMCID: PMC5458133 DOI: 10.1038/ncomms15655] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 04/13/2017] [Indexed: 12/16/2022] Open
Abstract
S -to-N acyl transfer is a high-yielding chemoselective process for amide bond formation. It is widely utilized by chemists for synthetic applications, including peptide and protein synthesis, chemical modification of proteins, protein-protein ligation and the development of probes and molecular machines. Recent advances in our understanding of S -to-N acyl transfer processes in biology and innovations in methodology for thioester formation and desulfurization, together with an extension of the size of cyclic transition states, have expanded the boundaries of this process well beyond peptide ligation. As the field develops, this chemistry will play a central role in our molecular understanding of Biology. The conversion of thioesters to amides via acyl transfer has become one of the most important synthetic techniques for the chemical synthesis and modification of proteins. This review discusses this S-to-N acyl transfer process, and highlights some of the key applications across chemistry and biology.
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Affiliation(s)
- Helen M. Burke
- School of Chemistry, Trinity College Dublin, Dublin D2, Ireland
| | | | - Eoin M. Scanlan
- School of Chemistry, Trinity College Dublin, Dublin D2, Ireland
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20
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Zwarycz AS, Fossat M, Akanyeti O, Lin Z, Rosenman DJ, Garcia AE, Royer CA, Mills KV, Wang C. V67L Mutation Fills an Internal Cavity To Stabilize RecA Mtu Intein. Biochemistry 2017; 56:2715-2722. [PMID: 28488863 DOI: 10.1021/acs.biochem.6b01264] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inteins mediate protein splicing, which has found extensive applications in protein science and biotechnology. In the Mycobacterium tuberculosis RecA mini-mini intein (ΔΔIhh), a single valine to leucine substitution at position 67 (V67L) dramatically increases intein stability and activity. However, crystal structures show that the V67L mutation causes minimal structural rearrangements, with a root-mean-square deviation of 0.2 Å between ΔΔIhh-V67 and ΔΔIhh-L67. Thus, the structural mechanisms for V67L stabilization and activation remain poorly understood. In this study, we used intrinsic tryptophan fluorescence, high-pressure nuclear magnetic resonance (NMR), and molecular dynamics (MD) simulations to probe the structural basis of V67L stabilization of the intein fold. Guanidine hydrochloride denaturation monitored by fluorescence yielded free energy changes (ΔGf°) of -4.4 and -6.9 kcal mol-1 for ΔΔIhh-V67 and ΔΔIhh-L67, respectively. High-pressure NMR showed that ΔΔIhh-L67 is more resistant to pressure-induced unfolding than ΔΔIhh-V67 is. The change in the volume of folding (ΔVf) was significantly larger for V67 (71 ± 2 mL mol-1) than for L67 (58 ± 3 mL mol-1) inteins. The measured difference in ΔVf (13 ± 3 mL mol-1) roughly corresponds to the volume of the additional methylene group for Leu, supporting the notion that the V67L mutation fills a nearby cavity to enhance intein stability. In addition, we performed MD simulations to show that V67L decreases side chain dynamics and conformational entropy at the active site. It is plausible that changes in cavities in V67L can also mediate allosteric effects to change active site dynamics and enhance intein activity.
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Affiliation(s)
- Allison S Zwarycz
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Martin Fossat
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Otar Akanyeti
- Department of Computer Science, Aberystwyth University , Ceredigion SY23 3FL, Wales, U.K
| | - Zhongqian Lin
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - David J Rosenman
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Angel E Garcia
- Center of Nonlinear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Catherine A Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Kenneth V Mills
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | - Chunyu Wang
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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21
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Minteer CJ, Siegart NM, Colelli KM, Liu X, Linhardt RJ, Wang C, Gomez AV, Reitter JN, Mills KV. Intein-Promoted Cyclization of Aspartic Acid Flanking the Intein Leads to Atypical N-Terminal Cleavage. Biochemistry 2017; 56:1042-1050. [PMID: 28165720 DOI: 10.1021/acs.biochem.6b00894] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein splicing is a post-translational reaction facilitated by an intein, or intervening protein, which involves the removal of the intein and the ligation of the flanking polypeptides, or exteins. A DNA polymerase II intein from Pyrococcus abyssi (Pab PolII intein) can promote protein splicing in vitro on incubation at high temperature. Mutation of active site residues Cys1, Gln185, and Cys+1 to Ala results in an inactive intein precursor, which cannot promote the steps of splicing, including cleavage of the peptide bond linking the N-extein and intein (N-terminal cleavage). Surprisingly, coupling the inactivating mutations to a change of the residue at the C-terminus of the N-extein (N-1 residue) from the native Asn to Asp reactivates N-terminal cleavage at pH 5. Similar "aspartic acid effects" have been observed in other proteins and peptides but usually only occur at lower pH values. In this case, however, the unusual N-terminal cleavage is abolished by mutations to catalytic active site residues and unfolding of the intein, indicating that this cleavage effect is mediated by the intein active site and the intein fold. We show via mass spectrometry that the reaction proceeds through cyclization of Asp resulting in anhydride formation coupled to peptide bond cleavage. Our results add to the richness of the understanding of the mechanism of protein splicing and provide insight into the stability of proteins at moderately low pH. The results also explain, and may help practitioners avoid, a side reaction that may complicate intein applications in biotechnology.
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Affiliation(s)
- Christopher J Minteer
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | - Nicolle M Siegart
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | - Kathryn M Colelli
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | | | | | | | - Alvin V Gomez
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | - Julie N Reitter
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
| | - Kenneth V Mills
- Department of Chemistry, College of the Holy Cross , Worcester, Massachusetts 01610, United States
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22
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Stevens AJ, Brown ZZ, Shah NH, Sekar G, Cowburn D, Muir TW. Design of a Split Intein with Exceptional Protein Splicing Activity. J Am Chem Soc 2016; 138:2162-5. [PMID: 26854538 PMCID: PMC4894280 DOI: 10.1021/jacs.5b13528] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein trans-splicing (PTS) by split inteins has found widespread use in chemical biology and biotechnology. Herein, we describe the use of a consensus design approach to engineer a split intein with enhanced stability and activity that make it more robust than any known PTS system. Using batch mutagenesis, we first conduct a detailed analysis of the difference in splicing rates between the Npu (fast) and Ssp (slow) split inteins of the DnaE family and find that most impactful residues lie on the second shell of the protein, directly adjacent to the active site. These residues are then used to generate an alignment of 73 naturally occurring DnaE inteins that are predicted to be fast. The consensus sequence from this alignment (Cfa) demonstrates both rapid protein splicing and unprecedented thermal and chaotropic stability. Moreover, when fused to various proteins including antibody heavy chains, the N-terminal fragment of Cfa exhibits increased expression levels relative to other N-intein fusions. The durability and efficiency of Cfa should improve current intein based technologies and may provide a platform for the development of new protein chemistry techniques.
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Affiliation(s)
- Adam J Stevens
- Department of Chemistry, Princeton University , Frick Laboratory, Princeton, New Jersey 08544, United States
| | - Zachary Z Brown
- Department of Chemistry, Princeton University , Frick Laboratory, Princeton, New Jersey 08544, United States
| | - Neel H Shah
- Department of Chemistry, Princeton University , Frick Laboratory, Princeton, New Jersey 08544, United States
| | - Giridhar Sekar
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Tom W Muir
- Department of Chemistry, Princeton University , Frick Laboratory, Princeton, New Jersey 08544, United States
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23
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SufB intein of Mycobacterium tuberculosis as a sensor for oxidative and nitrosative stresses. Proc Natl Acad Sci U S A 2015; 112:10348-53. [PMID: 26240361 DOI: 10.1073/pnas.1512777112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inteins are mobile genetic elements that self-splice at the protein level. Mycobacteria have inteins inserted into several important genes, including those corresponding to the iron-sulfur cluster assembly protein SufB. Curiously, the SufB inteins are found primarily in mycobacterial species that are potential human pathogens. Here we discovered an exceptional sensitivity of Mycobacterium tuberculosis SufB intein splicing to oxidative and nitrosative stresses when expressed in Escherichia coli. This effect results from predisposition of the intein's catalytic cysteine residues to oxidative and nitrosative modifications. Experiments with a fluorescent reporter system revealed that reactive oxygen species and reactive nitrogen species inhibit SufB extein ligation by forcing either precursor accumulation or N-terminal cleavage. We propose that splicing inhibition is an immediate, posttranslational regulatory response that can be either reversible, by inducing precursor accumulation, or irreversible, by inducing N-terminal cleavage, which may potentially channel mycobacteria into dormancy under extreme oxidative and nitrosative stresses.
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24
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Chung LW, Sameera WMC, Ramozzi R, Page AJ, Hatanaka M, Petrova GP, Harris TV, Li X, Ke Z, Liu F, Li HB, Ding L, Morokuma K. The ONIOM Method and Its Applications. Chem Rev 2015; 115:5678-796. [PMID: 25853797 DOI: 10.1021/cr5004419] [Citation(s) in RCA: 743] [Impact Index Per Article: 82.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lung Wa Chung
- †Department of Chemistry, South University of Science and Technology of China, Shenzhen 518055, China
| | - W M C Sameera
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Romain Ramozzi
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Alister J Page
- §Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan 2308, Australia
| | - Miho Hatanaka
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
| | - Galina P Petrova
- ∥Faculty of Chemistry and Pharmacy, University of Sofia, Bulgaria Boulevard James Bourchier 1, 1164 Sofia, Bulgaria
| | - Travis V Harris
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan.,⊥Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States
| | - Xin Li
- #State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhuofeng Ke
- ∇School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Fengyi Liu
- ○Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Hai-Bei Li
- ■School of Ocean, Shandong University, Weihai 264209, China
| | - Lina Ding
- ▲School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, Henan 450001, China
| | - Keiji Morokuma
- ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan
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25
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Bastiaansen KC, van Ulsen P, Wijtmans M, Bitter W, Llamas MA. Self-cleavage of the Pseudomonas aeruginosa Cell-surface Signaling Anti-sigma Factor FoxR Occurs through an N-O Acyl Rearrangement. J Biol Chem 2015; 290:12237-46. [PMID: 25809487 DOI: 10.1074/jbc.m115.643098] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Indexed: 11/06/2022] Open
Abstract
The Fox system of Pseudomonas aeruginosa is a cell-surface signaling (CSS) pathway employed by the bacterium to sense and respond to the presence of the heterologous siderophore ferrioxamine in the environment. This regulatory pathway controls the transcription of the foxA ferrioxamine receptor gene through the extracytoplasmic function sigma factor σ(FoxI). In the absence of ferrioxamine, the activity of σ(FoxI) is inhibited by the transmembrane anti-sigma factor FoxR. Upon binding of ferrioxamine by the FoxA receptor, FoxR is processed by a complex proteolytic cascade leading to the release and activation of σ(FoxI). Interestingly, we have recently shown that FoxR undergoes self-cleavage between the periplasmic Gly-191 and Thr-192 residues independent of the perception of ferrioxamine. This autoproteolytic event, which is widespread among CSS anti-sigma factors, produces two distinct domains that interact and function together to transduce the presence of the signal. In this work, we provide evidence that the self-cleavage of FoxR is not an enzyme-dependent process but is induced by an N-O acyl rearrangement. Mutation analysis showed that the nucleophilic side chain of the Thr-192 residue at +1 of the cleavage site is required for an attack on the preceding Gly-191, after which the resulting ester bond is likely hydrolyzed. Because the cleavage site is well preserved and the hydrolysis of periplasmic CSS anti-sigma factors is widely observed, we hypothesize that cleavage via an N-O acyl rearrangement is a conserved feature of these proteins.
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Affiliation(s)
- Karlijn C Bastiaansen
- From the Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada E-18008, Spain and Section of Molecular Microbiology, Department of Molecular Cell Biology and
| | - Peter van Ulsen
- Section of Molecular Microbiology, Department of Molecular Cell Biology and
| | - Maikel Wijtmans
- Division of Medicinal Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | - Wilbert Bitter
- Section of Molecular Microbiology, Department of Molecular Cell Biology and
| | - María A Llamas
- From the Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada E-18008, Spain and
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26
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Cronin M, Coolbaugh MJ, Nellis D, Zhu J, Wood DW, Nussinov R, Ma B. Dynamics differentiate between active and inactive inteins. Eur J Med Chem 2015; 91:51-62. [PMID: 25087201 PMCID: PMC4308580 DOI: 10.1016/j.ejmech.2014.07.094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/21/2014] [Accepted: 07/25/2014] [Indexed: 11/29/2022]
Abstract
The balance between stability and dynamics for active enzymes can be somewhat quantified by studies of intein splicing and cleaving reactions. Inteins catalyze the ligation of flanking host exteins while excising themselves. The potential for applications led to engineering of a mini-intein splicing domain, where the homing endonuclease domain of the Mycobacterium tuberculosis RecA (Mtu recA) intein was removed. The remaining domains were linked by several short peptides, but splicing activity in all was substantially lower than the full-length intein. Native splicing activity was restored in some cases by a V67L mutation. Using computations and experiments, we examine the impact of this mutation on the stability and conformational dynamics of the mini-intein splicing domain. Molecular dynamics simulations were used to delineate the factors that determine the active state, including the V67L mini-intein mutant, and peptide linker. We found that (1) the V67L mutation lowers the global fluctuations in all modeled mini-inteins, stabilizing the mini-intein constructs; (2) the connecting linker length affects intein dynamics; and (3) the flexibilities of the linker and intein core are higher in the active structure. We have observed that the interaction of the linker region and a turn region around residues 35-41 provides the pathway for the allostery interaction. Our experiments reveal that intein catalysis is characterized by non-linear Arrhenius plot, confirming the significant contribution of protein conformational dynamics to intein function. We conclude that while the V67L mutation stabilizes the global structure, cooperative dynamics of all intein regions appear more important for intein function than high stability. Our studies suggest that effectively quenching the conformational dynamics of an intein through engineered allosteric interactions could deactivate intein splicing or cleaving.
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Affiliation(s)
- Melissa Cronin
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA
| | - Michael J Coolbaugh
- Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, OH 43210, USA
| | - David Nellis
- Biopharmaceutical Development Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Jianwei Zhu
- School of Pharmacy, Shanghai Jiao Tong University, 800 DongChuan Road, Shanghai 200240, China
| | - David W Wood
- Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, OH 43210, USA
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA; Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.
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27
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Xie J, Du Z, Callahan B, Belfort M, Wang C. ¹H, ¹³C and ¹⁵N NMR assignments of a Drosophila Hedgehog autoprocessing domain. BIOMOLECULAR NMR ASSIGNMENTS 2014; 8:279-281. [PMID: 23765287 PMCID: PMC3884045 DOI: 10.1007/s12104-013-9500-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/03/2013] [Indexed: 06/02/2023]
Abstract
The Hedgehog (Hh) signaling pathway plays important roles in embryonic growth and patterning in different organisms. Abnormal activity of the Hh signaling pathway has been associated to cancers, holoprosencephaly and autism spectrum disorders. The backbone and side chain resonance assignments of a Drosophila Hh autoprocessing domain have been determined based on triple-resonance experiments with the [(13)C, (15)N]-labeled and [(2)H, (13)C, (15)N])-labeled proteins.
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Affiliation(s)
- Jian Xie
- Biochemistry and Biophysics Graduate Program, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Zhenming Du
- Biochemistry and Biophysics Graduate Program, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Brian Callahan
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Marlene Belfort
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA
| | - Chunyu Wang
- Biochemistry and Biophysics Graduate Program, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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28
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Abstract
The first crystal trans-structure of a naturally occurring split intein has been determined for the Npu (Nostoc punctiforme PCC73102) DnaE split intein. Guided by this structure, the residues NArg50 and CSer35, well conserved in DnaE split inteins, are identified to be critical in the trans-splicing of Npu DnaE split intein. An in vitro splicing assay demonstrates that NArg50 and CSer35 play synergistic roles in modulating its intein activity. The C-terminal CAsn36 exhibits two orientations of its side chain and interacts with both NArg50 and CSer35 through hydrogen bonding. These interactions likely facilitate the cyclization of asparagine in the course of protein splicing. The mutation of either residue reduces intein activity, and correlates with the low activity of the Ssp (Cyanobacterium synechocystis sp. strain PCC6803) DnaE split intein. On the other hand, NArg50 also forms a hydrogen bond with the highly conserved F-block CAsp17, thus influencing the N-S acyl shift during N-terminal cleavage. Sequence alignments show that residues NArg50 and CSer35 are rather conserved in those split inteins that lack a penultimate histidine residue. The conserved non-catalytic residues of split inteins modulate the efficiency of protein trans-splicing by hydrogen-bond interactions with the catalytic residues at the splice junction.
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29
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Yang C, Xue XS, Li X, Cheng JP. Computational Study on the Acidic Constants of Chiral Brønsted Acids in Dimethyl Sulfoxide. J Org Chem 2014; 79:4340-51. [DOI: 10.1021/jo500158e] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Chen Yang
- State Key
Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, and Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xiao-Song Xue
- State Key
Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, and Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xin Li
- State Key
Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, and Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Jin-Pei Cheng
- State Key
Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, and Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
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30
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Abstract
Inteins are nature's escape artists; they facilitate their excision from flanking polypeptides (exteins) concomitant with extein ligation to produce a mature host protein. Splicing requires sequential nucleophilic displacement reactions catalyzed by strategies similar to proteases and asparagine lyases. Inteins require precise reaction coordination rather than rapid turnover or tight substrate binding because they are single turnover enzymes with covalently linked substrates. This has allowed inteins to explore alternative mechanisms with different steps or to use different methods for activation and coordination of the steps. Pressing issues include understanding the underlying details of catalysis and how the splicing steps are controlled.
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Affiliation(s)
- Kenneth V Mills
- From the Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610
| | - Margaret A Johnson
- the Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, and
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31
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Mihaylov TT, Parac-Vogt TN, Pierloot K. A computational study of the glycylserine hydrolysis at physiological pH: a zwitterionic versus anionic mechanism. Org Biomol Chem 2014; 12:1395-404. [PMID: 24430931 DOI: 10.1039/c3ob42372g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hydrolysis of GlySer at physiological pH was investigated by modeling the most feasible reaction mechanisms in aqueous phase at the MP2/6-311+(2df,2p)//SMD-M06/6-311+(2df,2p) level of the theory. To refine the energies of the most relevant transition states along the reaction paths the cluster-continuum concept was adopted. The hydrolytic process could proceed through two competitive mechanisms involving either the zwitterionic or the anionic form of GlySer. The calculations suggest that at physiological pH the actual mechanism is most probably mixed, anionic-zwitterionic. In this reaction scheme the first stage of N→O acyl transfer involves the anionic form whereas the second stage, during which the resultant ester is hydrolyzed, most likely involves the zwitterionic ester form of GlySer. The energy requirement for the first reaction stage is estimated to be slightly lower than for the second one. The calculated activation parameters (e.g. ΔG(#) = 27.8 kcal mol(-1)) for the nucleophilic addition of a water molecule to the ester carbonyl group of the zwitterionic ester are in good agreement with the experimentally determined values at pD 7.4 (ΔG(#) = 28.7 kcal mol(-1)).
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Affiliation(s)
- Tzvetan T Mihaylov
- KU Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001, Leuven, Belgium.
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32
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Mihaylov TT, Parac-Vogt TN, Pierloot K. A Mechanistic Study of the Spontaneous Hydrolysis of Glycylserine as the Simplest Model for Protein Self-Cleavage. Chemistry 2013; 20:456-66. [DOI: 10.1002/chem.201303564] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Indexed: 11/05/2022]
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33
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Abstract
Inteins are intervening protein sequences that undergo self-excision from a precursor protein with the concomitant ligation of the flanking polypeptides. Split inteins are expressed in two separated halves, and the recognition and association of two halves are the first crucial step for initiating trans-splicing. In the present study, we carried out the structural and thermodynamic analysis on the interaction of two halves of DnaE split intein from Synechocystis sp. PCC6803. Both isolated halves (IN and IC) are disordered and undergo conformational transition from disorder to order upon association. ITC (isothermal titration calorimetry) reveals that the highly favourable enthalpy change drives the association of the two halves, overcoming the unfavourable entropy change. The high flexibility of two fragments and the marked thermodynamic preference provide a robust association for the formation of the well-folded IN/IC complex, which is the basis for reconstituting the trans-splicing activity of DnaE split intein.
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34
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Volkmann G, Mootz HD. Recent progress in intein research: from mechanism to directed evolution and applications. Cell Mol Life Sci 2013; 70:1185-206. [PMID: 22926412 PMCID: PMC11113529 DOI: 10.1007/s00018-012-1120-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 07/23/2012] [Accepted: 08/06/2012] [Indexed: 10/27/2022]
Abstract
Inteins catalyze a post-translational modification known as protein splicing, where the intein removes itself from a precursor protein and concomitantly ligates the flanking protein sequences with a peptide bond. Over the past two decades, inteins have risen from a peculiarity to a rich source of applications in biotechnology, biomedicine, and protein chemistry. In this review, we focus on developments of intein-related research spanning the last 5 years, including the three different splicing mechanisms and their molecular underpinnings, the directed evolution of inteins towards improved splicing in exogenous protein contexts, as well as novel applications of inteins for cell biology and protein engineering, which were made possible by a clearer understanding of the protein splicing mechanism.
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Affiliation(s)
- Gerrit Volkmann
- Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
| | - Henning D. Mootz
- Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
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35
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Dearden AK, Callahan B, Roey PV, Li Z, Kumar U, Belfort M, Nayak SK. A conserved threonine spring-loads precursor for intein splicing. Protein Sci 2013; 22:557-63. [PMID: 23423655 DOI: 10.1002/pro.2236] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 11/12/2022]
Abstract
Protein splicing is an autocatalytic process where an "intein" self-cleaves from a precursor and ligates the flanking N- and C-"extein" polypeptides. Inteins occur in all domains of life and have myriad uses in biotechnology. Although the reaction steps of protein splicing are known, mechanistic details remain incomplete, particularly the initial peptide rearrangement at the N-terminal extein/intein junction. Recently, we proposed that this transformation, an N-S acyl shift, is accelerated by a localized conformational strain, between the intein's catalytic cysteine (Cys1) and the neighboring glycine (Gly-1) in the N-extein. That proposal was based on the crystal structure of a catalytically competent trapped precursor. Here, we define the structural origins and mechanistic relevance of the conformational strain using a combination of quantum mechanical simulations, mutational analysis, and X-ray crystallography. Our results implicate a conserved, but largely unstudied, threonine residue of the Ssp DnaE intein (Thr69) as the mediator of conformational strain through hydrogen bonding. Further, the strain imposed by this residue is shown to position the splice junction in a manner that enhances the rate of the N-S acyl shift substantially. Taken together, our results not only provide fundamental understanding of the control of the first step of protein splicing but also have important implications in various biotechnological applications that require precursor manipulation.
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Affiliation(s)
- Albert K Dearden
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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36
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Binschik J, Mootz HD. Chemical bypass of intein-catalyzed N-S acyl shift in protein splicing. Angew Chem Int Ed Engl 2013; 52:4260-4. [PMID: 23468274 DOI: 10.1002/anie.201208863] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/13/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Jens Binschik
- Institute of Biochemistry, University of Muenster, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
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37
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Binschik J, Mootz HD. Chemischer “Bypass” des Intein-katalysierten N-S-Acyltransfers im Proteinspleißen. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201208863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Roca M, Aranda J, Moliner V, Tuñón I. Modeling methods for studying post-translational and transcriptional modifying enzymes. Curr Opin Chem Biol 2012; 16:465-71. [PMID: 23127358 DOI: 10.1016/j.cbpa.2012.10.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/20/2012] [Accepted: 10/11/2012] [Indexed: 10/27/2022]
Abstract
Biological catalysis is a complex chemical process that involves not only electronic reorganization in the substrate but also the reorganization of the catalyst. This complexity is even larger in the case of post-transcriptional and post-translational modifications which may involve the interaction between two biomacromolecules. However, the development over the past decades of new computational methods and strategies is offering a detailed molecular picture of the catalytic event and a deep understanding of the mechanisms of chemical reactions in biological environments. Here we review the efforts made in the last years to model catalysis in post-transcriptional and post-translational processes. We stress on the advantages and problems of the different computational strategies and their applicability in different cases.
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Affiliation(s)
- Maite Roca
- Departamento de Química Física, Universitat de València, 46100 Burjassot, Spain
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39
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Zhu X, Lopes PEM, Shim J, MacKerell AD. Intrinsic energy landscapes of amino acid side-chains. J Chem Inf Model 2012; 52:1559-72. [PMID: 22582825 PMCID: PMC3398815 DOI: 10.1021/ci300079j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Amino acid side-chain conformational properties influence the overall structural and dynamic properties of proteins and, therefore, their biological functions. In this study, quantum mechanical (QM) potential energy surfaces for the rotation of side-chain χ(1) and χ(2) torsions in dipeptides in the alphaR, beta, and alphaL backbone conformations were calculated. The QM energy surfaces provide a broad view of the intrinsic conformational properties of each amino acid side-chain. The extent to which intrinsic energetics dictates side-chain orientation was studied through comparisons of the QM energy surfaces with χ(1) and χ(2) free energy surfaces from probability distributions obtained from a survey of high resolution crystal structures. In general, the survey probability maxima are centered in minima of the QM surfaces as expected for sp(3) (or sp(2) for χ(2) of Asn, Phe, Trp, and Tyr) atom centers with strong variations between amino acids occurring in the energies of the minima indicating intrinsic differences in rotamer preferences. High correlations between the QM and survey data were found for hydrophobic side-chains except Met, suggesting minimal influence of the protein and solution environments on their conformational distributions. Conversely, low correlations for polar or charged side-chains indicate a dominant role of the environment in stabilizing conformations that are not intrinsically favored. Data also link the presence of off-rotamers in His and Trp to favorable interactions with the backbone. Results also suggest that the intrinsic energetics of the side-chains of Phe and Tyr may play important roles in protein folding and stability. Analyses on whether intrinsic side-chain energetics can influence backbone preference identified a strong correlation for residues in the alphaL backbone conformation. It is suggested that this correlation reflects the intrinsic instability of the alphaL backbone such that assumption of this backbone conformation is facilitated by intrinsically favorable side-chain conformations. Together our results offer a broad overview of the conformational properties of amino acid side-chains and the QM data may be used as target data for force field optimization.
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Affiliation(s)
- Xiao Zhu
- Department of Pharmaceutical Sciences, University of Maryland, School of Pharmacy, 20 Penn Street HSFII, Baltimore, Maryland 21201, USA
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40
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Tori K, Cheriyan M, Pedamallu CS, Contreras MA, Perler FB. The Thermococcus kodakaraensis Tko CDC21-1 intein activates its N-terminal splice junction in the absence of a conserved histidine by a compensatory mechanism. Biochemistry 2012; 51:2496-505. [PMID: 22380677 DOI: 10.1021/bi201840k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inteins and other self-catalytic enzymes, such as glycosylasparaginases and hedgehog precursors, initiate autocleavage by converting a peptide bond to a (thio)ester bond when Ser, Thr, or Cys undergoes an N-[S/O] acyl migration assisted by residues within the precursor. Previous studies have shown that a His at position 10 in intein Block B is essential for this initial acyl migration and N-terminal splice junction cleavage. This His is present in all inteins identified to date except the Thermococcus kodakaraensis Tko CDC21-1 intein orthologs and the inactive Arthrobacter species FB24 Arth_1007 intein. This study demonstrates that the Tko CDC21-1 intein is fully active and has replaced the lost catalytic function normally provided by the Block B His using a compensatory mechanism involving a conserved ortholog-specific basic residue (Lys(58)) present outside the standard intein conserved motifs. We propose that Lys(58) catalyzes the initial N-S acyl migration by stabilizing the thiazolidine-tetrahedral intermediate, allowing it to be resolved by water-mediated hydrolysis rather than by protonating the leaving group as His is theorized to do in many other inteins. Autoprocessing enzymes may have more flexibility in evolving catalytic variations because high reaction rates are not required when performing single-turnover reactions on "substrates" that are covalently attached to the enzyme. Consequently, inteins have more flexibility to sample catalytic mechanisms, providing insight into various strategies that enzymes use to accomplish catalysis.
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Affiliation(s)
- Kazuo Tori
- New England BioLabs, Ipswich, Massachusetts 01938, United States
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41
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Schwarzer D, Ludwig C, Thiel IV, Mootz HD. Probing intein-catalyzed thioester formation by unnatural amino acid substitutions in the active site. Biochemistry 2011; 51:233-42. [PMID: 22182201 DOI: 10.1021/bi2014823] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inteins are single-turnover catalysts that splice themselves out of a precursor polypeptide chain. For most inteins, the first step of protein splicing is the formation of a thioester through an N-S acyl shift at the upstream splice junction. However, the mechanism by which this reaction is achieved and the impact of mutations in and close to the active site remain unclear on the atomic level. To investigate these questions, we have further explored a split variant of the Ssp DnaB intein by introducing substitutions with unnatural amino acids within the short synthetic N-terminal fragment. A previously reported collapse of the oxythiazolidine anion intermediate into a thiazoline ring was found to be specificially dependent on the methyl side chain of the flanking Ala(-1). The stereoisomer d-Ala and the constitutional isomers β-Ala and sarcosine did not lead to this side reaction but rather supported splicing. Substitution of the catalytic Cys1 with homocysteine strongly inhibited protein splicing; however, thioester formation was not impaired. These results argue against the requirement of a base to deprotonate the catalytic thiol group prior to the N-S acyl shift, because it should be misaligned for optimal proton abstraction. A previously described mutant intein evolved for more general splicing in different sequence contexts could even rather efficiently splice with this homocysteine. Our findings show the large impact of some subtle structural changes on the protein splicing pathway, but also the remarkable tolerance toward other changes. Such insights will also be important for the biotechnological exploitation of inteins.
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Affiliation(s)
- Dirk Schwarzer
- Institute of Biochemistry, University of Muenster, Wilhelm-Klemm-Strasse 2, 48149 Münster, Germany
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42
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Mujika JI, Lopez X, Mulholland AJ. Mechanism of C-terminal intein cleavage in protein splicing from QM/MM molecular dynamics simulations. Org Biomol Chem 2011; 10:1207-18. [PMID: 22179261 DOI: 10.1039/c1ob06444d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protein splicing is a post-translational process in which a biologically inactive protein is activated by the release of a segment denoted as an intein. The process involves four steps. In the third, the scission of the intein takes place after the cyclization of the last amino acid of the segment, an asparagine. Little is known about the chemical reaction necessary for this cyclization. Experiments demonstrate that two histidines (the penultimate amino acid of the intein, and a histidine located 10 amino acids upstream) are relevant in the cyclization of the asparagine. We have investigated the mechanism and determinants of reaction in the GyrA intein focusing on the requirements for asparagine activation for its cyclization. First, the influence that the protonation states of these two histidines have on the orientation of the asparagine side chain is investigated by means of molecular dynamics simulation. Molecular dynamics simulations using the CHARMM27 force field were carried out on the three possible protonation states for each of these two histidines. The results indicate that the only protonation state in which the conformation of the system is suitable for cyclization is when the penultimate histidine is fully protonated (positively charged), and the upstream histidine is in the His(ε) neutral tautomeric form. The free energy profile for the reaction in which the asparagine is activated by a proton transfer to the upstream histidine is presented, computed by hybrid quantum mechanics/molecular mechanics (QM/MM) umbrella sampling molecular dynamics at the SCCDFTB/CHARMM27 level of theory. The calculated free energy barrier for the reaction is 19.0 kcal mol(-1). B3LYP/6-31+G(d) QM/MM single-point calculations give a qualitatively a similar energy profile, although with somewhat higher energy barriers, in good agreement with the value derived from experiment of 25 kcal mol(-1) at 60 °C. QM/MM molecular dynamics simulations of the reactant, activated reactant and intermediate states highlight the importance of the Arg181-Val182-Asp183 segment in catalysing the reaction. Overall, the results indicate that nucleophilic activation of the asparagine for its cyclization by the upstream histidine acting as the base is a plausible mechanism for the C-terminal cleavage in protein splicing.
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Affiliation(s)
- Jon I Mujika
- Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center (DIPC, P. K. 1072, 20080, Donostia, Euskadi, Spain.
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43
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Du Z, Liu J, Albracht CD, Hsu A, Chen W, Marieni MD, Colelli KM, Williams JE, Reitter JN, Mills KV, Wang C. Structural and mutational studies of a hyperthermophilic intein from DNA polymerase II of Pyrococcus abyssi. J Biol Chem 2011; 286:38638-38648. [PMID: 21914805 PMCID: PMC3207444 DOI: 10.1074/jbc.m111.290569] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 09/09/2011] [Indexed: 11/06/2022] Open
Abstract
Protein splicing is a precise self-catalyzed process in which an intein excises itself from a precursor with the concomitant ligation of the flanking polypeptides (exteins). Protein splicing proceeds through a four-step reaction but the catalytic mechanism is not fully understood at the atomic level. We report the solution NMR structures of the hyperthermophilic Pyrococcus abyssi PolII intein, which has a noncanonical C-terminal glutamine instead of an asparagine. The NMR structures were determined to a backbone root mean square deviation of 0.46 Å and a heavy atom root mean square deviation of 0.93 Å. The Pab PolII intein has a common HINT (hedgehog intein) fold but contains an extra β-hairpin that is unique in the structures of thermophilic inteins. The NMR structures also show that the Pab PolII intein has a long and disordered loop in place of an endonuclease domain. The N-terminal Cys-1 amide is hydrogen bonded to the Thr-90 hydroxyl in the conserved block-B TXXH motif and the Cys-1 thiol forms a hydrogen bond with the block F Ser-166. Mutating Thr-90 to Ala dramatically slows N-terminal cleavage, supporting its pivotal role in promoting the N-S acyl shift. Mutagenesis also showed that Thr-90 and His-93 are synergistic in catalyzing the N-S acyl shift. The block F Ser-166 plays an important role in coordinating the steps of protein splicing. NMR spin relaxation indicates that the Pab PolII intein is significantly more rigid than mesophilic inteins, which may contribute to the higher optimal temperature for protein splicing.
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Affiliation(s)
- Zhenming Du
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Jiajing Liu
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Clayton D Albracht
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Alice Hsu
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Wen Chen
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Michelle D Marieni
- Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610
| | - Kathryn M Colelli
- Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610
| | - Jennie E Williams
- Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610
| | - Julie N Reitter
- Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610
| | - Kenneth V Mills
- Department of Chemistry, College of the Holy Cross, Worcester, Massachusetts 01610.
| | - Chunyu Wang
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180.
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44
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Liu J, Du Z, Albracht CD, Naidu RO, Mills KV, Wang C. 1H, 13C, and 15N NMR assignments of the Pyrococcus abyssi DNA polymerase II intein. BIOMOLECULAR NMR ASSIGNMENTS 2011; 5:233-235. [PMID: 21519863 PMCID: PMC3166996 DOI: 10.1007/s12104-011-9307-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 04/14/2011] [Indexed: 05/30/2023]
Abstract
Protein splicing is a precise post-translational process mediated by inteins. Inteins are intervening proteins that cleave themselves from a precursor protein while joining the flanking sequences. Here we report the (15)N, (13)C, and (1)H chemical shift assignments of the intein from DNA polymerase II of Pyrococcus abyssi (Pab PolII intein), which has been recombinantly overexpressed and isotopically labeled. The NMR assignments of Pab PolII intein are essential for solution structure determination and protein dynamics study.
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Affiliation(s)
- Jiajing Liu
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Zhenming Du
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Clayton D. Albracht
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Roshni O. Naidu
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Kenneth V. Mills
- Department of Chemistry, College of the Holy Cross, Worcester, MA, 01610
| | - Chunyu Wang
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180
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45
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Volkmann G, Liu XQ. Intein lacking conserved C-terminal motif G retains controllable N-cleavage activity. FEBS J 2011; 278:3431-46. [PMID: 21787376 DOI: 10.1111/j.1742-4658.2011.08266.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A split-intein consists of two complementary fragments (N-intein and C-intein) that can associate to carry out protein trans-splicing. The Ssp GyrB S11 split-intein is an engineered unconventional split-intein consisting of a 150-amino-acid N-intein and an extremely small six-amino-acid C-intein, which comprises the conserved intein motif G. Here, we show that fusion proteins containing the 150-amino-acid N-intein could be triggered to undergo controllable N-cleavage in vitro when the six-amino-acid C-intein or a derivative thereof was added as a synthetic peptide in trans. More importantly, we discovered, unexpectedly, that the 150-amino-acid N-intein could be induced by strong nucleophiles to undergo N-cleavage in vitro, and in Escherichia coli cells, in the absence of the motif G-containing six-amino-acid C-intein. This finding indicated that the first step of the protein splicing mechanism (acyl shift) could occur in the absence of the entire motif G. Extensive kinetic analyses revealed that both the motif G residues and the Ser+1 residue positively influenced N-cleavage rate constants and yields. The 150-amino-acid N-intein could also tolerate various unrelated sequences appended to its C-terminus without disruption of the N-cleavage function, suggesting that the catalytic pocket of the intein has considerable structural flexibility. Our findings reveal interesting insights into intein structure-function relationships, and demonstrate a new and potentially more useful method of controllable, intein-mediated N-cleavage for protein engineering applications.
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Affiliation(s)
- Gerrit Volkmann
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada.
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46
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Lewis CA, Wolfenden R. Amide Bonds to the Nitrogen Atoms of Cysteine and Serine as “Weak Points” in the Backbones of Proteins. Biochemistry 2011; 50:7259-64. [DOI: 10.1021/bi200813s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Charles A. Lewis
- Department
of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Richard Wolfenden
- Department
of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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47
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Qi X, Meng Q, Liu XQ. Spontaneous C-cleavage of a mini-intein without its conserved N-terminal motif A. FEBS Lett 2011; 585:2513-8. [PMID: 21741975 DOI: 10.1016/j.febslet.2011.06.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 06/21/2011] [Accepted: 06/28/2011] [Indexed: 11/26/2022]
Abstract
Previously, the C-terminal fragment of a split intein was known to undergo controllable C-cleavage at its C-terminus only when the N-terminal fragment of the intein was added. Here we constructed a similar split intein from the Ssp DnaX intein, but we unexpectedly observed that its C-terminal 136-aa fragment could undergo spontaneous C-cleavage without the N-terminal fragment that was up to 15 aa long and contained the conserved intein motif A. This C-cleavage activity was significantly decreased by a mutation of the conserved Thr residue in the conserved intein motif B. These findings suggest a robust intein structure in the absence of motif A and a larger role of motif B in the third step of the protein splicing mechanism.
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Affiliation(s)
- Xingmei Qi
- Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai, PR China
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48
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Du Z, Zheng Y, Patterson M, Liu Y, Wang C. pK(a) coupling at the intein active site: implications for the coordination mechanism of protein splicing with a conserved aspartate. J Am Chem Soc 2011; 133:10275-82. [PMID: 21604815 DOI: 10.1021/ja203209f] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein splicing is a robust multistep posttranslational process catalyzed by inteins. In the Mtu RecA intein, a conserved block-F aspartate (D422) coordinates different steps in protein splicing, but the precise mechanism is unclear. Solution NMR shows that D422 has a strikingly high pK(a) of 6.1, two units above the normal pK(a) of aspartate. The elevated pK(a) of D422 is coupled to the depressed pK(a) of another active-site residue, the block-A cysteine (C1). A C1A mutation lowers the D422 pK(a) to normal, while a D422G mutation increases the C1 pK(a) from 7.5 to 8.5. The pK(a) coupling and NMR structure determination demonstrate that protonated D422 serves as a hydrogen bond donor to stabilize the C1 thiolate and promote the N-S acyl shift, the first step of protein splicing. Additionally, in vivo splicing assays with mutations of D422 to Glu, Cys, and Ser show that the deprotonated aspartate is essential for splicing, most likely by deprotonating and activating the downstream nucleophile in transesterification, the second step of protein splicing. We propose that the sequential protonation and deprotonation of the D422 side chain is the coordination mechanism for the first two steps of protein splicing.
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Affiliation(s)
- Zhenming Du
- Biology Department, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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49
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Shemella P, Topilina N, Soga I, Pereira B, Belfort G, Belfort M, Nayak S. Electronic structure of neighboring extein residue modulates intein C-terminal cleavage activity. Biophys J 2011; 100:2217-25. [PMID: 21539790 PMCID: PMC3149237 DOI: 10.1016/j.bpj.2011.02.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 01/25/2011] [Accepted: 02/04/2011] [Indexed: 11/27/2022] Open
Abstract
Protein splicing is an autocatalytic reaction where an intervening element (intein) is excised and the remaining two flanking sequences (exteins) are joined. The reaction requires specific conserved residues, and activity may be affected by both the intein and the extein sequence. Predicting how sequence will affect activity is a challenging task. Based on first-principles density functional theory and multiscale quantum mechanics/molecular mechanics, we report C-terminal cleavage reaction rates for five mutations at the first residue of the C-extein (+1), and describe molecular properties that may be used as predictors for future mutations. Independently, we report on experimental characterization of the same set of mutations at the +1 residue resulting in a wide range of C-terminal cleavage activities. With some exceptions, there is general agreement between computational rates and experimental cleavage, giving molecular insight into previous claims that the +1 extein residue affects intein catalysis. These data suggest utilization of attenuating +1 mutants for intein-mediated protein manipulations because they facilitate precursor accumulation in vivo for standard purification schemes. A more detailed analysis of the "+1 effect" will also help to predict sequence-defined effects on insertion points of the intein into proteins of interest.
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Affiliation(s)
- Philip T. Shemella
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York
| | | | - Ikko Soga
- Wadsworth Center, New York State Department of Health, Albany, New York
| | - Brian Pereira
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
- Wadsworth Center, New York State Department of Health, Albany, New York
| | - Georges Belfort
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
| | - Marlene Belfort
- Wadsworth Center, New York State Department of Health, Albany, New York
| | - Saroj K. Nayak
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York
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50
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Pereira B, Shemella PT, Amitai G, Belfort G, Nayak SK, Belfort M. Spontaneous proton transfer to a conserved intein residue determines on-pathway protein splicing. J Mol Biol 2010; 406:430-42. [PMID: 21185311 DOI: 10.1016/j.jmb.2010.12.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 12/16/2010] [Indexed: 02/06/2023]
Abstract
The discovery of inteins, which are protein-splicing elements, has stimulated interest for various applications in chemical biology, bioseparations, drug delivery, and sensor development. However, for inteins to effectively contribute to these applications, an increased mechanistic understanding of cleavage and splicing reactions is required. While the multistep chemical reaction that leads to splicing is often explored and utilized, it is not clear how the intein navigates through the reaction space. The sequence of reaction steps must progress in concert in order to yield efficient splicing while minimizing off-pathway cleavage reactions. In this study, we demonstrate that formation of a previously identified branched intermediate is the critical step for determining splicing over cleavage products. By combining experimental assays and quantum mechanical simulations, we identify the electrostatic interactions that are important to the dynamics of the reaction steps. We illustrate, via an animated simulation trajectory, a proton transfer from the first C-terminal extein residue to a conserved aspartate, which synchronizes the multistep enzymatic reaction that is key to splicing. This work provides new insights into the complex interplay between critical active-site residues in the protein splicing mechanism, thereby facilitating biotechnological application while shedding light on multistep enzyme activity.
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Affiliation(s)
- Brian Pereira
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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