1
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Pan W, Biswas T, Shahabi S, Suryajaya W, Vasquez A, Du Q, Ghosh G, Wang VYF. Phosphorylation-induced flexibility of proto-oncogenic Bcl3 regulates transcriptional activation by NF-κB p52 homodimer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.30.601400. [PMID: 38979190 PMCID: PMC11230411 DOI: 10.1101/2024.06.30.601400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The overexpression of proto-oncogene Bcl3 is observed in various cancers. Bcl3 is extensively phosphorylated and associates with homodimers of NF-κB p50 and p52 to regulate transcription. Through cellular and biochemical assays, we observed that phospho-mimetic Glu substitution at Ser366 in addition to previously studied Ser33, 114 and 446 is necessary to switch Bcl3 from an IκB-like inhibitor to a transcriptional activator. To study interactive features of p52 and Bcl3, and phosphorylation- mediated changes in Bcl3 that regulate DNA-binding by p52, we performed HDX-MS of both Bcl3 and p52 within various complexes. Nature of interactions within Bcl3:(p52:p52) complex in presence and absence of DNA, differential flexibility of Bcl3, and allosteric changes in Bcl3 upon phospho-modifications revealed why a facile accommodation of DNA requires phosphorylation. The inhibitory nature of unphosphorylated Bcl3 on DNA binding by p52:p52 also relieved by a C-terminal deletion of Bcl3. Overall, this study revealed mechanistic bases of how Bcl3 phosphorylation regulates transcriptional potential of NF-κB and intricate cell physiology, a dysregulation of which can lead to cancers.
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2
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Torres-Paris C, Chen Y, Xiao L, Song HJ, Chen P, Komives EA. The autoactivation of human single-chain urokinase-type plasminogen activator (uPA). J Biol Chem 2023; 299:105179. [PMID: 37607618 PMCID: PMC10520878 DOI: 10.1016/j.jbc.2023.105179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/29/2023] [Accepted: 08/15/2023] [Indexed: 08/24/2023] Open
Abstract
Most serine proteases are synthesized as inactive zymogens that are activated by cleavage by another protease in a tightly regulated mechanism. The urokinase-type plasminogen activator (uPA) and plasmin cleave and activate each other, constituting a positive feedback loop. How this mutual activation cycle begins has remained a mystery. We used hydrogen deuterium exchange mass spectrometry to characterize the dynamic differences between the inactive single-chain uPA (scuPA) and its active form two-chain uPA (tcuPA). The results show that the C-terminal β-barrel and the area around the new N terminus have significantly reduced dynamics in tcuPA as compared with scuPA. We also show that the zymogen scuPA is inactive but can, upon storage, become active in the absence of external proteases. In addition to plasmin, the tcuPA can activate scuPA by cleavage at K158, a process called autoactivation. Unexpectedly, tcuPA can cleave at position 158 even when this site is mutated. TcuPA can also cleave scuPA after K135 or K136 in the disordered linker, which generates the soluble protease domain of uPA. Plasmin cleaves scuPA exclusively after K158 and at a faster rate than tcuPA. We propose a mechanism by which the uPA receptor dimerization could promote autoactivation of scuPA on cell surfaces. These results resolve long-standing controversies in the literature surrounding the mechanism of uPA activation.
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Affiliation(s)
- Constanza Torres-Paris
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Yueyi Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Lufan Xiao
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Harriet J Song
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Pingyu Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA.
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3
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Baughman HER, Narang D, Chen W, Villagrán Suárez AC, Lee J, Bachochin MJ, Gunther TR, Wolynes PG, Komives EA. An intrinsically disordered transcription activation domain increases the DNA binding affinity and reduces the specificity of NFκB p50/RelA. J Biol Chem 2022; 298:102349. [PMID: 35934050 PMCID: PMC9440430 DOI: 10.1016/j.jbc.2022.102349] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 12/03/2022] Open
Abstract
Many transcription factors contain intrinsically disordered transcription activation domains (TADs), which mediate interactions with coactivators to activate transcription. Historically, DNA-binding domains and TADs have been considered as modular units, but recent studies have shown that TADs can influence DNA binding. Whether these results can be generalized to more TADs is not clear. Here, we biophysically characterized the NFκB p50/RelA heterodimer including the RelA TAD and investigated the TAD's influence on NFκB-DNA interactions. In solution, we show the RelA TAD is disordered but compact, with helical tendency in two regions that interact with coactivators. We determined that the presence of the TAD increased the stoichiometry of NFκB-DNA complexes containing promoter DNA sequences with tandem κB recognition motifs by promoting the binding of NFκB dimers in excess of the number of κB sites. In addition, we measured the binding affinity of p50/RelA for DNA containing tandem κB sites and single κB sites. While the presence of the TAD enhanced the binding affinity of p50/RelA for all κB sequences tested, it also increased the affinity for nonspecific DNA sequences by over 10-fold, leading to an overall decrease in specificity for κB DNA sequences. In contrast, previous studies have generally reported that TADs decrease DNA-binding affinity and increase sequence specificity. Our results reveal a novel function of the RelA TAD in promoting binding to nonconsensus DNA, which sheds light on previous observations of extensive nonconsensus DNA binding by NFκB in vivo in response to strong inflammatory signals.
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Affiliation(s)
- Hannah E R Baughman
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Dominic Narang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Wei Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Amalia C Villagrán Suárez
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Joan Lee
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Maxwell J Bachochin
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Tristan R Gunther
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Peter G Wolynes
- Department of Chemistry and Center for Theoretical Biological Physics, Rice University, Houston, Texas, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA.
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4
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Chen W, Lu W, Wolynes PG, Komives E. Single-molecule conformational dynamics of a transcription factor reveals a continuum of binding modes controlling association and dissociation. Nucleic Acids Res 2021; 49:11211-11223. [PMID: 34614173 PMCID: PMC8565325 DOI: 10.1093/nar/gkab874] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 09/10/2021] [Accepted: 09/22/2021] [Indexed: 12/24/2022] Open
Abstract
Binding and unbinding of transcription factors to DNA are kinetically controlled to regulate the transcriptional outcome. Control of the release of the transcription factor NF-κB from DNA is achieved through accelerated dissociation by the inhibitor protein IκBα. Using single-molecule FRET, we observed a continuum of conformations of NF-κB in free and DNA-bound states interconverting on the subseconds to minutes timescale, comparable to in vivo binding on the seconds timescale, suggesting that structural dynamics directly control binding kinetics. Much of the DNA-bound NF-κB is partially bound, allowing IκBα invasion to facilitate DNA dissociation. IκBα induces a locked conformation where the DNA-binding domains of NF-κB are too far apart to bind DNA, whereas a loss-of-function IκBα mutant retains the NF-κB conformational ensemble. Overall, our results suggest a novel mechanism with a continuum of binding modes for controlling association and dissociation of transcription factors.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
| | - Wei Lu
- Center for Theoretical Biological Physics, Departments of Chemistry, Physics, and Biosciences, Rice University, Houston, Texas 77005, USA
| | - Peter G Wolynes
- Center for Theoretical Biological Physics, Departments of Chemistry, Physics, and Biosciences, Rice University, Houston, Texas 77005, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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5
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Scrosati PM, Yin V, Konermann L. Hydrogen/Deuterium Exchange Measurements May Provide an Incomplete View of Protein Dynamics: a Case Study on Cytochrome c. Anal Chem 2021; 93:14121-14129. [PMID: 34644496 DOI: 10.1021/acs.analchem.1c02471] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many aspects of protein function rely on conformational fluctuations. Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) provides a window into these dynamics. Despite the widespread use of HDX-MS, it remains unclear whether this technique provides a truly comprehensive view of protein dynamics. HDX is mediated by H-bond-opening/closing events, implying that HDX methods provide an H-bond-centric view. This raises the question if there could be fluctuations that leave the H-bond network unaffected, thereby rendering them undetectable by HDX-MS. We explore this issue in experiments on cytochrome c (cyt c). Compared to the Fe(II) protein, Fe(III) cyt c shows enhanced deuteration on both the distal and proximal sides of the heme. Previous studies have attributed the enhanced dynamics of Fe(III) cyt c to the facile and reversible rupture of the distal M80-Fe(III) bond. Using molecular dynamics (MD) simulations, we conducted a detailed analysis of various cyt c conformers. Our MD data confirm that rupture of the M80-Fe(III) contact triggers major reorientation of the distal Ω loop. Surprisingly, this event takes place with only miniscule H-bonding alterations. In other words, the distal loop dynamics are almost "HDX-silent". Moreover, distal loop movements cannot account for enhanced dynamics on the opposite (proximal) side of the heme. Instead, enhanced deuteration of Fe(III) cyt c is attributed to sparsely populated conformers where both the distal (M80) and proximal (H18) coordination bonds have been ruptured, along with opening of numerous H-bonds on both sides of the heme. We conclude that there can be major structural fluctuations that are only weakly coupled to changes in H-bonding, making them virtually impossible to track by HDX-MS. In such cases, HDX-MS may provide an incomplete view of protein dynamics.
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Affiliation(s)
- Pablo M Scrosati
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Victor Yin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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James EI, Murphree TA, Vorauer C, Engen JR, Guttman M. Advances in Hydrogen/Deuterium Exchange Mass Spectrometry and the Pursuit of Challenging Biological Systems. Chem Rev 2021; 122:7562-7623. [PMID: 34493042 PMCID: PMC9053315 DOI: 10.1021/acs.chemrev.1c00279] [Citation(s) in RCA: 102] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Solution-phase hydrogen/deuterium
exchange (HDX) coupled to mass
spectrometry (MS) is a widespread tool for structural analysis across
academia and the biopharmaceutical industry. By monitoring the exchangeability
of backbone amide protons, HDX-MS can reveal information about higher-order
structure and dynamics throughout a protein, can track protein folding
pathways, map interaction sites, and assess conformational states
of protein samples. The combination of the versatility of the hydrogen/deuterium
exchange reaction with the sensitivity of mass spectrometry has enabled
the study of extremely challenging protein systems, some of which
cannot be suitably studied using other techniques. Improvements over
the past three decades have continually increased throughput, robustness,
and expanded the limits of what is feasible for HDX-MS investigations.
To provide an overview for researchers seeking to utilize and derive
the most from HDX-MS for protein structural analysis, we summarize
the fundamental principles, basic methodology, strengths and weaknesses,
and the established applications of HDX-MS while highlighting new
developments and applications.
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Affiliation(s)
- Ellie I James
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Taylor A Murphree
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Clint Vorauer
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - John R Engen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Miklos Guttman
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
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7
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Lumpkin RJ, Ahmad AS, Blake R, Condon CJ, Komives EA. The Mechanism of NEDD8 Activation of CUL5 Ubiquitin E3 Ligases. Mol Cell Proteomics 2021; 20:100019. [PMID: 33268465 PMCID: PMC7950132 DOI: 10.1074/mcp.ra120.002414] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/27/2022] Open
Abstract
Cullin RING E3 ligases (CRLs) ubiquitylate hundreds of important cellular substrates. Here we have assembled and purified the Ankyrin repeat and SOCS Box protein 9 CUL5 RBX2 ligase (ASB9-CRL) in vitro and show how it ubiquitylates one of its substrates, CKB. CRLs occasionally collaborate with RING between RING E3 ligases (RBRLs), and indeed, mass spectrometry analysis showed that CKB is specifically ubiquitylated by the ASB9-CRL-ARIH2-UBE2L3 complex. Addition of other E2s such as UBE2R1 or UBE2D2 contributes to polyubiquitylation but does not alter the sites of CKB ubiquitylation. Hydrogen–deuterium exchange mass spectrometry (HDX-MS) analysis revealed that CUL5 neddylation allosterically exposes its ARIH2 binding site, promoting high-affinity binding, and it also sequesters the NEDD8 E2 (UBE2F) binding site on RBX2. Once bound, ARIH2 helices near the Ariadne domain active site are exposed, presumably relieving its autoinhibition. These results allow us to propose a model of how neddylation activates ASB-CRLs to ubiquitylate their substrates. ARIH2 is required for ASB9CRL to polyubiquitylate 4/18 lysines on one creatine kinase subunit. HDX-MS reveals long-range allosteric opening of a cleft in CUL5 where the ARIH2 RBRL binds. HDX-MS reveals that neddylation of CUL5 alters the RBX2 conformation away from binding the E2∼NEDD8. HDX-MS reveals opening of the ARIH2 active site upon binding CUL5, thus releasing its autoinhibition.
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Affiliation(s)
- Ryan J Lumpkin
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Alla S Ahmad
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Rachel Blake
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Christopher J Condon
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA.
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8
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Lumpkin RJ, Baker RW, Leschziner AE, Komives EA. Structure and dynamics of the ASB9 CUL-RING E3 Ligase. Nat Commun 2020; 11:2866. [PMID: 32513959 PMCID: PMC7280518 DOI: 10.1038/s41467-020-16499-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 05/01/2020] [Indexed: 01/23/2023] Open
Abstract
The Cullin 5 (CUL5) Ring E3 ligase uses adaptors Elongins B and C (ELOB/C) to bind different SOCS-box-containing substrate receptors, determining the substrate specificity of the ligase. The 18-member ankyrin and SOCS box (ASB) family is the largest substrate receptor family. Here we report cryo-EM data for the substrate, creatine kinase (CKB) bound to ASB9-ELOB/C, and for full-length CUL5 bound to the RING protein, RBX2, which binds various E2s. To date, no full structures are available either for a substrate-bound ASB nor for CUL5. Hydrogen-deuterium exchange (HDX-MS) mapped onto a full structural model of the ligase revealed long-range allostery extending from the substrate through CUL5. We propose a revised allosteric mechanism for how CUL-E3 ligases function. ASB9 and CUL5 behave as rigid rods, connected through a hinge provided by ELOB/C transmitting long-range allosteric crosstalk from the substrate through CUL5 to the RBX2 flexible linker.
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Affiliation(s)
- Ryan J Lumpkin
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92092-0378, USA
| | - Richard W Baker
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC, USA
| | - Andres E Leschziner
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92092-0378, USA.
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9
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Lumpkin RJ, Komives EA. DECA, A Comprehensive, Automatic Post-processing Program for HDX-MS Data. Mol Cell Proteomics 2019; 18:2516-2523. [PMID: 31594786 PMCID: PMC6885705 DOI: 10.1074/mcp.tir119.001731] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/17/2019] [Indexed: 11/06/2022] Open
Abstract
Amide hydrogen-deuterium exchange mass spectrometry (HDX-MS) has become widely popular for mapping protein-ligand interfaces, for understanding protein-protein interactions, and for discovering dynamic allostery. Several platforms are now available which provide large data sets of amide hydrogen/deuterium exchange mass spectrometry (HDX-MS) data. Although many of these platforms provide some down-stream processing, a comprehensive software that provides the most commonly used down-stream processing tools such as automatic back-exchange correction options, analysis of overlapping peptides, calculations of relative deuterium uptake into regions of the protein after such corrections, rigorous statistical analysis of the significance of uptake differences, and generation of high quality figures for data presentation is not yet available. Here we describe the Deuterium Exchange Correction and Analysis (DECA) software package, which provides all these downstream processing options for data from the most popular mass spectrometry platforms. The major functions of the software are demonstrated on sample data.
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Affiliation(s)
- Ryan J Lumpkin
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92092-0378
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92092-0378.
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10
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Perez-Riba A, Komives E, Main ERG, Itzhaki LS. Decoupling a tandem-repeat protein: Impact of multiple loop insertions on a modular scaffold. Sci Rep 2019; 9:15439. [PMID: 31659184 PMCID: PMC6817815 DOI: 10.1038/s41598-019-49905-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 08/29/2019] [Indexed: 11/25/2022] Open
Abstract
The simple topology and modular architecture of tandem-repeat proteins such as tetratricopeptide repeats (TPRs) and ankyrin repeats makes them straightforward to dissect and redesign. Repeat-protein stability can be manipulated in a predictable way using site-specific mutations. Here we explore a different type of modification - loop insertion - that will enable a simple route to functionalisation of this versatile scaffold. We previously showed that a single loop insertion has a dramatically different effect on stability depending on its location in the repeat array. Here we dissect this effect by a combination of multiple and alternated loop insertions to understand the origins of the context-dependent loss in stability. We find that the scaffold is remarkably robust in that its overall structure is maintained. However, adjacent repeats are now only weakly coupled, and consequently the increase in solvent protection, and thus stability, with increasing repeat number that defines the tandem-repeat protein class is lost. Our results also provide us with a rulebook with which we can apply these principles to the design of artificial repeat proteins with precisely tuned folding landscapes and functional capabilities, thereby paving the way for their exploitation as a versatile and truly modular platform in synthetic biology.
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Affiliation(s)
- Albert Perez-Riba
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
- Donnelly Centre for Cellular & Biomolecular Research, University of Toronto, Toronto, Canada
| | - Elizabeth Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0378, USA
| | - Ewan R G Main
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
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11
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Kopcho N, Chang G, Komives EA. Dynamics of ABC Transporter P-glycoprotein in Three Conformational States. Sci Rep 2019; 9:15092. [PMID: 31641149 PMCID: PMC6805939 DOI: 10.1038/s41598-019-50578-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/10/2019] [Indexed: 12/25/2022] Open
Abstract
We used hydrogen-deuterium exchange mass spectrometry (HDX-MS) to obtain a comprehensive view of transporter dynamics (85.8% sequence coverage) occurring throughout the multidrug efflux transporter P-glycoprotein (P-gp) in three distinct conformational states: predominantly inward-facing apo P-gp, pre-hydrolytic (E552Q/E1197Q) P-gp bound to Mg+2-ATP, and outward-facing P-gp bound to Mg+2-ADP-VO4−3. Nucleotide affinity was measured with bio-layer interferometry (BLI), which yielded kinetics data that fit a two Mg+2-ATP binding-site model. This model has one high affinity site (3.2 ± 0.3 µM) and one low affinity site (209 ± 25 µM). Comparison of deuterium incorporation profiles revealed asymmetry between the changes undergone at the critical interfaces where nucleotide binding domains (NBDs) contact intracellular helices (ICHs). In the pre-hydrolytic state, both interfaces between ICHs and NBDs decreased exchange to similar extents relative to inward-facing P-gp. In the outward-facing state, the ICH-NBD1 interface showed decreased exchange, while the ICH-NBD2 interface showed less of an effect. The extracellular loops (ECLs) showed reduced deuterium uptake in the pre-hydrolytic state, consistent with an occluded conformation. While in the outward-facing state, increased ECL exchange corresponding to EC domain opening was observed. These findings point toward asymmetry between both NBDs, and they suggest that pre-hydrolytic P-gp occupies an occluded conformation.
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Affiliation(s)
- Noah Kopcho
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0378, USA
| | - Geoffrey Chang
- School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Dr, La Jolla, AC, 92093-0754, USA.,Department of Pharmacology, School of Medicine, University of California, San Diego, 9500 Gilman Dr, La Jolla, AC, 92093-0754, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0378, USA.
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12
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Ahdash Z, Pyle E, Allen WJ, Corey RA, Collinson I, Politis A. HDX-MS reveals nucleotide-dependent, anti-correlated opening and closure of SecA and SecY channels of the bacterial translocon. eLife 2019; 8:47402. [PMID: 31290743 PMCID: PMC6639072 DOI: 10.7554/elife.47402] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 07/09/2019] [Indexed: 01/28/2023] Open
Abstract
The bacterial Sec translocon is a multi-protein complex responsible for translocating diverse proteins across the plasma membrane. For post-translational protein translocation, the Sec-channel – SecYEG – associates with the motor protein SecA to mediate the ATP-dependent transport of pre-proteins across the membrane. Previously, a diffusional-based Brownian ratchet mechanism for protein secretion has been proposed; the structural dynamics required to facilitate this mechanism remain unknown. Here, we employ hydrogen-deuterium exchange mass spectrometry (HDX-MS) to reveal striking nucleotide-dependent conformational changes in the Sec protein-channel from Escherichia coli. In addition to the ATP-dependent opening of SecY, reported previously, we observe a counteracting, and ATP-dependent, constriction of SecA around the pre-protein. ATP binding causes SecY to open and SecA to close; while, ADP produced by hydrolysis, has the opposite effect. This alternating behaviour could help impose the directionality of the Brownian ratchet for protein transport through the Sec machinery.
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Affiliation(s)
- Zainab Ahdash
- Department of Chemistry, King's College London, London, United Kingdom
| | - Euan Pyle
- Department of Chemistry, King's College London, London, United Kingdom.,Department of Chemistry, Imperial College London, London, United Kingdom
| | | | - Robin A Corey
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Argyris Politis
- Department of Chemistry, King's College London, London, United Kingdom
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