1
|
Maya-Martinez R, Xu Y, Guthertz N, Walko M, Karamanos TK, Sobott F, Breeze AL, Radford SE. Dimers of D76N-β 2-microglobulin display potent antiamyloid aggregation activity. J Biol Chem 2022; 298:102659. [PMID: 36328246 PMCID: PMC9712992 DOI: 10.1016/j.jbc.2022.102659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/20/2022] [Accepted: 10/28/2022] [Indexed: 11/05/2022] Open
Abstract
Self-association of WT β2-microglobulin (WT-β2m) into amyloid fibrils is associated with the disorder dialysis related amyloidosis. In the familial variant D76N-β2m, the single amino acid substitution enhances the aggregation propensity of the protein dramatically and gives rise to a disorder that is independent of renal dysfunction. Numerous biophysical and structural studies on WT- and D76N-β2m have been performed in order to better understand the structure and dynamics of the native proteins and their different potentials to aggregate into amyloid. However, the structural properties of transient D76N-β2m oligomers and their role(s) in assembly remained uncharted. Here, we have utilized NMR methods, combined with photo-induced crosslinking, to detect, trap, and structurally characterize transient dimers of D76N-β2m. We show that the crosslinked D76N-β2m dimers have different structures from those previously characterized for the on-pathway dimers of ΔN6-β2m and are unable to assemble into amyloid. Instead, the crosslinked D76N-β2m dimers are potent inhibitors of amyloid formation, preventing primary nucleation and elongation/secondary nucleation when added in substoichiometric amounts with D76N-β2m monomers. The results highlight the specificity of early protein-protein interactions in amyloid formation and show how mapping these interfaces can inform new strategies to inhibit amyloid assembly.
Collapse
Affiliation(s)
- Roberto Maya-Martinez
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Yong Xu
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Nicolas Guthertz
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Martin Walko
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, Leeds, United Kingdom
| | - Theodoros K Karamanos
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Alexander L Breeze
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
| |
Collapse
|
2
|
Cawood EE, Guthertz N, Ebo JS, Karamanos TK, Radford SE, Wilson AJ. Modulation of Amyloidogenic Protein Self-Assembly Using Tethered Small Molecules. J Am Chem Soc 2020; 142:20845-20854. [PMID: 33253560 PMCID: PMC7729939 DOI: 10.1021/jacs.0c10629] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
Protein–protein
interactions (PPIs) are involved in many
of life’s essential biological functions yet are also an underlying
cause of several human diseases, including amyloidosis. The modulation
of PPIs presents opportunities to gain mechanistic insights into amyloid
assembly, particularly through the use of methods which can trap specific
intermediates for detailed study. Such information can also provide
a starting point for drug discovery. Here, we demonstrate that covalently
tethered small molecule fragments can be used to stabilize specific
oligomers during amyloid fibril formation, facilitating the structural
characterization of these assembly intermediates. We exemplify the
power of covalent tethering using the naturally occurring truncated
variant (ΔN6) of the human protein β2-microglobulin
(β2m), which assembles into amyloid fibrils associated
with dialysis-related amyloidosis. Using this approach, we have trapped
tetramers formed by ΔN6 under conditions which would normally
lead to fibril formation and found that the degree of tetramer stabilization
depends on the site of the covalent tether and the nature of the protein–fragment
interaction. The covalent protein–ligand linkage enabled structural
characterization of these trapped, off-pathway oligomers using X-ray
crystallography and NMR, providing insight into why tetramer stabilization
inhibits amyloid assembly. Our findings highlight the power of “post-translational
chemical modification” as a tool to study biological molecular
mechanisms.
Collapse
Affiliation(s)
- Emma E Cawood
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Nicolas Guthertz
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Jessica S Ebo
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Theodoros K Karamanos
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Andrew J Wilson
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.,School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
| |
Collapse
|
3
|
Effect of Ionic Strength on Thioflavin-T Affinity to Amyloid Fibrils and Its Fluorescence Intensity. Int J Mol Sci 2020; 21:ijms21238916. [PMID: 33255444 PMCID: PMC7727833 DOI: 10.3390/ijms21238916] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
The formation of amyloid fibrils is linked to multiple neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease. Despite years of research and countless studies on the topic of such aggregate formation, as well as their resulting structure, the current knowledge is still fairly limited. One of the main aspects prohibiting effective aggregation tracking is the environment’s effect on amyloid-specific dyes, namely thioflavin-T (ThT). Currently, there are only a few studies hinting at ionic strength being one of the factors that modulate the dye’s binding affinity and fluorescence intensity. In this work we explore this effect under a range of ionic strength conditions, using insulin, lysozyme, mouse prion protein, and α-synuclein fibrils. We show that ionic strength is an extremely important factor affecting both the binding affinity, as well as the fluorescence intensity of ThT.
Collapse
|
4
|
Loureiro RJS, Faísca PFN. The Early Phase of β2-Microglobulin Aggregation: Perspectives From Molecular Simulations. Front Mol Biosci 2020; 7:578433. [PMID: 33134317 PMCID: PMC7550760 DOI: 10.3389/fmolb.2020.578433] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/08/2020] [Indexed: 11/24/2022] Open
Abstract
Protein β2-microglobulin is the causing agent of two amyloidosis, dialysis related amyloidosis (DRA), affecting the bones and cartilages of individuals with chronic renal failure undergoing long-term hemodialysis, and a systemic amyloidosis, found in one French family, which impairs visceral organs. The protein’s small size and its biomedical significance attracted the attention of theoretical scientists, and there are now several studies addressing its aggregation mechanism in the context of molecular simulations. Here, we review the early phase of β2-microglobulin aggregation, by focusing on the identification and structural characterization of monomers with the ability to trigger aggregation, and initial small oligomers (dimers, tetramers, hexamers etc.) formed in the so-called nucleation phase. We focus our analysis on results from molecular simulations and integrate our views with those coming from in vitro experiments to provide a broader perspective of this interesting field of research. We also outline directions for future computer simulation studies.
Collapse
Affiliation(s)
- Rui J S Loureiro
- Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Patrícia F N Faísca
- Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal.,Department of Physics, Faculty of Sciences, University of Lisboa, Lisbon, Portugal
| |
Collapse
|
5
|
Hoop CL, Zhu J, Bhattacharya S, Tobita CA, Radford SE, Baum J. Collagen I Weakly Interacts with the β-Sheets of β 2-Microglobulin and Enhances Conformational Exchange To Induce Amyloid Formation. J Am Chem Soc 2020; 142:1321-1331. [PMID: 31875390 PMCID: PMC7135851 DOI: 10.1021/jacs.9b10421] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Amyloidogenesis is
significant in both protein function and pathology.
Amyloid formation of folded, globular proteins is commonly initiated
by partial or complete unfolding. However, how this unfolding event
is triggered for proteins that are otherwise stable in their native
environments is not well understood. The accumulation of the immunoglobulin
protein β2-microglobulin (β2m) into
amyloid plaques in the joints of long-term hemodialysis patients is
the hallmark of dialysis-related amyloidosis (DRA). While β2m does not form amyloid unassisted near neutral pH in vitro, the localization of β2m deposits
to joint spaces suggests a role for the local extracellular matrix
(ECM) proteins, specifically collagens, in promoting amyloid formation.
Indeed, collagen and other ECM components have been observed to facilitate
β2m amyloid formation, but the large size and anisotropy
of the complex, combined with the low affinity of these interactions,
have limited atomic-level elucidation of the amyloid-promoting mechanism(s)
by these molecules. Using solution NMR approaches that uniquely probe
weak interactions in large molecular weight complexes, we are able
to map the binding interfaces on β2m for collagen
I and detect collagen I-induced μs–ms time-scale dynamics
in the β2m backbone. By combining solution NMR relaxation
methods and 15N-dark-state exchange saturation transfer
experiments, we propose a model in which weak, multimodal collagen
I−β2m interactions promote exchange with a
minor population of amyloid-competent species to induce fibrillogenesis.
The results portray the intimate role of the environment in switching
an innocuous protein into an amyloid-competent state, rationalizing
the localization of amyloid deposits in DRA.
Collapse
Affiliation(s)
- Cody L Hoop
- Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Jie Zhu
- Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | | | - Caitlyn A Tobita
- Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, Faculty of Biological Sciences , University of Leeds , Leeds LS2 9JT , U.K
| | - Jean Baum
- Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| |
Collapse
|
6
|
Karamanos TK, Jackson MP, Calabrese AN, Goodchild SC, Cawood EE, Thompson GS, Kalverda AP, Hewitt EW, Radford SE. Structural mapping of oligomeric intermediates in an amyloid assembly pathway. eLife 2019; 8:46574. [PMID: 31552823 PMCID: PMC6783270 DOI: 10.7554/elife.46574] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 09/24/2019] [Indexed: 01/02/2023] Open
Abstract
Transient oligomers are commonly formed in the early stages of amyloid assembly. Determining the structure(s) of these species and defining their role(s) in assembly is key to devising new routes to control disease. Here, using a combination of chemical kinetics, NMR spectroscopy and other biophysical methods, we identify and structurally characterize the oligomers required for amyloid assembly of the protein ΔN6, a truncation variant of human β2-microglobulin (β2m) found in amyloid deposits in the joints of patients with dialysis-related amyloidosis. The results reveal an assembly pathway which is initiated by the formation of head-to-head non-toxic dimers and hexamers en route to amyloid fibrils. Comparison with inhibitory dimers shows that precise subunit organization determines amyloid assembly, while dynamics in the C-terminal strand hint to the initiation of cross-β structure formation. The results provide a detailed structural view of early amyloid assembly involving structured species that are not cytotoxic.
Collapse
Affiliation(s)
- Theodoros K Karamanos
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Matthew P Jackson
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Antonio N Calabrese
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Sophia C Goodchild
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Emma E Cawood
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Gary S Thompson
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Arnout P Kalverda
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Eric W Hewitt
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Sheena E Radford
- The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| |
Collapse
|
7
|
Achour A, Broggini L, Han X, Sun R, Santambrogio C, Buratto J, Visentin C, Barbiroli A, De Luca CMG, Sormanni P, Moda F, De Simone A, Sandalova T, Grandori R, Camilloni C, Ricagno S. Biochemical and biophysical comparison of human and mouse beta-2 microglobulin reveals the molecular determinants of low amyloid propensity. FEBS J 2019; 287:546-560. [PMID: 31420997 DOI: 10.1111/febs.15046] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 07/09/2019] [Accepted: 08/15/2019] [Indexed: 01/01/2023]
Abstract
The molecular bases of amyloid aggregation propensity are still poorly understood, especially for proteins that display a stable folded native structure. A prototypic example is human beta-2 microglobulin (β2m), which, when accumulated in patients, gives rise to dialysis-related amyloidosis. Interestingly, although the physiologic concentration of β2m in mice is five times higher than that found in human patients, no amyloid deposits are observed in mice. Moreover, murine β2m (mβ2m) not only displays a lower amyloid propensity both in vivo and in vitro but also inhibits the aggregation of human β2m in vitro. Here, we compared human and mβ2m for their aggregation propensity, ability to form soluble oligomers, stability, three-dimensional structure and dynamics. Our results indicate that mβ2m low-aggregation propensity is due to two concomitant aspects: the low-aggregation propensity of its primary sequence combined with the absence of high-energy amyloid-competent conformations under native conditions. The identification of the specific properties determining the low-aggregation propensity of mouse β2m will help delineate the molecular risk factors which cause a folded protein to aggregate.
Collapse
Affiliation(s)
- Adnane Achour
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, Solna, Sweden.,Division of Infectious Diseases, Karolinska University Hospital, Solna, Sweden
| | - Luca Broggini
- Dipartimento di Bioscienze, Università degli Studi di Milano, Italy
| | - Xiao Han
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, Solna, Sweden.,Division of Infectious Diseases, Karolinska University Hospital, Solna, Sweden
| | - Renhua Sun
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, Solna, Sweden.,Division of Infectious Diseases, Karolinska University Hospital, Solna, Sweden
| | - Carlo Santambrogio
- Dipartimento di Biotecnologie e Bioscienze, Università Milano-Bicocca, Italy
| | - Jeremie Buratto
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, Solna, Sweden.,Division of Infectious Diseases, Karolinska University Hospital, Solna, Sweden
| | | | - Alberto Barbiroli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, Italy
| | - Chiara Maria Giulia De Luca
- Divisione di Neurologia 5 - Neuropatologia, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | | | - Fabio Moda
- Divisione di Neurologia 5 - Neuropatologia, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | | | - Tatyana Sandalova
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, Solna, Sweden.,Division of Infectious Diseases, Karolinska University Hospital, Solna, Sweden
| | - Rita Grandori
- Dipartimento di Biotecnologie e Bioscienze, Università Milano-Bicocca, Italy
| | - Carlo Camilloni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Italy
| | - Stefano Ricagno
- Dipartimento di Bioscienze, Università degli Studi di Milano, Italy
| |
Collapse
|
8
|
J S Loureiro R, Vila-Viçosa D, Machuqueiro M, Shakhnovich EI, F N Faísca P. The Early Phase of β2m Aggregation: An Integrative Computational Study Framed on the D76N Mutant and the ΔN6 Variant. Biomolecules 2019; 9:biom9080366. [PMID: 31416179 PMCID: PMC6722664 DOI: 10.3390/biom9080366] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 08/08/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022] Open
Abstract
Human β2-microglobulin (b2m) protein is classically associated with dialysis-related amyloidosis (DRA). Recently, the single point mutant D76N was identified as the causative agent of a hereditary systemic amyloidosis affecting visceral organs. To get insight into the early stage of the β2m aggregation mechanism, we used molecular simulations to perform an in depth comparative analysis of the dimerization phase of the D76N mutant and the ΔN6 variant, a cleaved form lacking the first six N-terminal residues, which is a major component of ex vivo amyloid plaques from DRA patients. We also provide first glimpses into the tetramerization phase of D76N at physiological pH. Results from extensive protein–protein docking simulations predict an essential role of the C- and N-terminal regions (both variants), as well as of the BC-loop (ΔN6 variant), DE-loop (both variants) and EF-loop (D76N mutant) in dimerization. The terminal regions are more relevant under acidic conditions while the BC-, DE- and EF-loops gain importance at physiological pH. Our results recapitulate experimental evidence according to which Tyr10 (A-strand), Phe30 and His31 (BC-loop), Trp60 and Phe62 (DE-loop) and Arg97 (C-terminus) act as dimerization hot-spots, and further predict the occurrence of novel residues with the ability to nucleate dimerization, namely Lys-75 (EF-loop) and Trp-95 (C-terminus). We propose that D76N tetramerization is mainly driven by the self-association of dimers via the N-terminus and DE-loop, and identify Arg3 (N-terminus), Tyr10, Phe56 (D-strand) and Trp60 as potential tetramerization hot-spots.
Collapse
Affiliation(s)
- Rui J S Loureiro
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Diogo Vila-Viçosa
- BioISI-Biosystems & Integrative Sciences Institute and Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Miguel Machuqueiro
- BioISI-Biosystems & Integrative Sciences Institute and Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Patrícia F N Faísca
- BioISI-Biosystems & Integrative Sciences Institute and Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.
| |
Collapse
|
9
|
Sjekloća L, Ferré-D'Amaré AR. Binding between G Quadruplexes at the Homodimer Interface of the Corn RNA Aptamer Strongly Activates Thioflavin T Fluorescence. Cell Chem Biol 2019; 26:1159-1168.e4. [PMID: 31178406 DOI: 10.1016/j.chembiol.2019.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 03/08/2019] [Accepted: 04/29/2019] [Indexed: 12/21/2022]
Abstract
Thioflavin T (ThT) is widely used for the detection of amyloids. Many unrelated DNAs and RNAs that contain G-quadruplex motifs also bind ThT and strongly activate its fluorescence. To elucidate the structural basis of ThT binding to G quadruplexes and its fluorescence turn-on, we determined its co-crystal structure with the homodimeric RNA Corn, which contains two G quadruplexes. We found that two ThT molecules bind in the dimer interface, constrained by a G quartet from each protomer into a maximally fluorescent planar conformation. The unliganded Corn homodimer crystal structure reveals a collapsed fluorophore-binding site. In solution, Corn must fluctuate between this and an open, binding-competent conformation. A co-crystal structure with another benzothiazole derivate, thiazole orange (TO), also shows binding at the Corn homodimer interface. As the bound ThT and TO make no interactions with the RNA backbone, their Corn co-crystal structures likely explain their fluorescence activation upon sequence-independent DNA and RNA G-quadruplex binding.
Collapse
Affiliation(s)
- Ljiljana Sjekloća
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, 50 South Drive MSC 8012, Bethesda, MD 20892-8012, USA
| | - Adrian R Ferré-D'Amaré
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, 50 South Drive MSC 8012, Bethesda, MD 20892-8012, USA.
| |
Collapse
|
10
|
McPherson A, Larson SB. Investigation into the binding of dyes within protein crystals. Acta Crystallogr F Struct Biol Commun 2018; 74:593-602. [PMID: 30198893 PMCID: PMC6130428 DOI: 10.1107/s2053230x18010300] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/17/2018] [Indexed: 11/10/2022] Open
Abstract
It was found that the crystals of at least a dozen different proteins could be thoroughly stained to an intense color with a panel of dyes. Many, if not most, of the stained protein crystals retained the dyes almost indefinitely when placed in large volumes of dye-free mother liquor. Dialysis experiments showed that most of the dyes that were retained in crystals also bound to the protein when free in solution; less frequently, some dyes bound only in the crystal. The experiments indicated a strong association of the dyes with the proteins. Four protein crystals were investigated by X-ray diffraction to ascertain the mode of binding. These were crystals of lysozyme, thaumatin, trypsin inhibited with benzamidine and satellite tobacco mosaic virus. In 30 X-ray analyses of protein crystal-dye complexes, in only three difference Fourier maps was any difference electron density present that was consistent with the binding of dye molecules, and even in these three cases (thaumatin plus thioflavin T, xylene cyanol and m-cresol purple) the amount of dye observed was inadequate to explain the intense color of the crystals. It was concluded that the dye molecules, which are clearly inside the crystals, are disordered but are paradoxically tightly bound to the protein. It is speculated that the dyes, which exhibit large hydrophobic cores and peripheral charged groups, may interact with the crystalline proteins in the manner of conventional detergents.
Collapse
Affiliation(s)
- Alexander McPherson
- Molecular Biology and Biochemistry, University of California Irvine, 560 Steinhaus Hall, Irvine, CA 92697-3900, USA
| | - Steven B. Larson
- Molecular Biology and Biochemistry, University of California Irvine, 560 Steinhaus Hall, Irvine, CA 92697-3900, USA
| |
Collapse
|
11
|
Rovnyagina NR, Sluchanko NN, Tikhonova TN, Fadeev VV, Litskevich AY, Maskevich AA, Shirshin EA. Binding of thioflavin T by albumins: An underestimated role of protein oligomeric heterogeneity. Int J Biol Macromol 2017; 108:284-290. [PMID: 29208556 DOI: 10.1016/j.ijbiomac.2017.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/30/2017] [Accepted: 12/01/2017] [Indexed: 12/22/2022]
Abstract
Amyloid fibrils formation is the well-known hallmark of various neurodegenerative diseases. Thioflavin T (ThT)-based fluorescence assays are widely used to detect and characterize fibrils, however, if performed in bioliquids, the analysis can be biased due to the presence of other, especially abundant, proteins. Particularly, it is known that albumin may bind ThT, although the binding mechanism remains debatable. Here the role of low-order albumin oligomers in ThT binding is investigated using time-resolved fluorometry and size-exclusion chromatography. Under conditions used, the fraction of dimers in human (HSA) and bovine (BSA) serum albumin solutions is as low as ∼7%, however, it is responsible for ∼50% of ThT binding. For both albumins, the binding affinity was estimated to be ∼200 and ∼40μM for monomeric and dimeric species, respectively. Molecular docking suggested that ThT preferentially binds in the hydrophobic pocket of subdomain IB of albumin monomer in a similar position but with a variable torsion angle, resulting in a lower fluorescence enhancement (∼40-fold) compared to amyloid fibrils (∼1000-fold). Dimerization of albumin presumably creates an extra binding site at the subunit interface. These results demonstrate the underestimated role of low-order albumin oligomers that can be highly relevant when analyzing drugs binding using fluorescence spectroscopy.
Collapse
Affiliation(s)
| | - Nikolai N Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow 119071, Russia; Department of biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
| | - Tatiana N Tikhonova
- International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
| | - Victor V Fadeev
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
| | | | | | - Evgeny A Shirshin
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991, Russia.
| |
Collapse
|
12
|
Loureiro RJS, Vila-Viçosa D, Machuqueiro M, Shakhnovich EI, Faísca PFN. A tale of two tails: The importance of unstructured termini in the aggregation pathway of β2-microglobulin. Proteins 2017; 85:2045-2057. [DOI: 10.1002/prot.25358] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/13/2017] [Accepted: 07/22/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Rui J. S. Loureiro
- BioISI - Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa; Lisboa Portugal
| | - Diogo Vila-Viçosa
- Centro de Química e Bioquímica; Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa; Lisboa Portugal
| | - Miguel Machuqueiro
- Centro de Química e Bioquímica; Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa; Lisboa Portugal
| | - Eugene I. Shakhnovich
- Department of Chemistry and Chemical Biology; Harvard University; Cambridge Massachusetts
| | - Patricia F. N. Faísca
- BioISI - Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa; Lisboa Portugal
- Departamento de Física; Faculdade de Ciências, Universidade de Lisboa; Lisboa Portugal
| |
Collapse
|