1
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Mukunda DC, Basha S, D'Souza MG, Chandra S, Ameera K, Stanley W, Mazumder N, Mahato KK. Label-free visualization of unfolding and crosslinking mediated protein aggregation in nonenzymatically glycated proteins. Analyst 2024; 149:4029-4040. [PMID: 38963259 DOI: 10.1039/d4an00358f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Nonenzymatic glycation (NEG) unfolds and crosslinks proteins, resulting in aggregation. Label-free evaluation of such structural changes, without disturbing molecular integrity, would be beneficial for understanding the fundamental mechanisms of protein aggregation. The current study demonstrates the assessment of NEG-induced protein aggregation by combining autofluorescence (AF) spectroscopy and imaging. The methylglyoxal (MG) induced protein unfolding and the formation of cross-linking advanced glycation end-products (AGEs) leading to aggregation were evaluated using deep-UV-induced-autofluorescence (dUV-AF) spectroscopy in proteins with distinct structural characteristics. Since the AGEs formed on proteins are fluorescent, the study demonstrated the possibility of autofluorescence imaging of NEG-induced protein aggregates. Autofluorescence spectroscopy can potentially reveal molecular alterations such as protein unfolding and cross-linking. In contrast, AGE-based autofluorescence imaging offers a means to visually explore the structural arrangement of aggregates, regardless of whether they are amyloid or non-amyloid in nature.
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Affiliation(s)
| | - Shaik Basha
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - Meagan Gail D'Souza
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - Subhash Chandra
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - K Ameera
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - Weena Stanley
- Department of Medicine, Kasturba Medical College, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Nirmal Mazumder
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| | - Krishna Kishore Mahato
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
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2
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Chikkanayakanahalli Mukunda D, Rodrigues J, Chandra S, Mazumder N, Vitkin A, Kishore Mahato K. Protein classification by autofluorescence spectral shape analysis using machine learning. Talanta 2024; 267:125167. [PMID: 37714041 DOI: 10.1016/j.talanta.2023.125167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 08/23/2023] [Accepted: 09/04/2023] [Indexed: 09/17/2023]
Abstract
Depending on the relative numbers and spatial arrangement of Tryptophan (Trp; W) and Tyrosine (Tyr; Y) residues, different proteins produce distinct autofluorescence (AF) spectral shapes when excited at ∼280 nm. Yet, considering the vast number and heterogeneous forms in nature, visual analysis and precise identification of proteins based on their AF spectra is challenging and further compounded in cases when different proteins produce substantially similar AF spectral shapes. There is, thus, a serious need to develop a methodology to address this problem. The current study proposes a practical technology to quickly identify proteins using machine learning (ML) algorithms based on their AF spectra. Specifically, AF spectra of fifteen different standard proteins of varying origin with distinct structural and Trp/Tyr compositions were recorded; based on the spectral features selected by the Minimum-Redundancy-Maximum-Relevance (mRMR) algorithm, a multiclass Support Vector Machine (SVM) learning model with Radial Basis Function (RBF), Polynomial, and Linear kernels classified the proteins with high accuracy of 99.06%, 99.03%, and 98.29% respectively. Since protein identification is the key to understand biological functions and disease diagnosis, the proposed methodology could offer a viable alternative to and improve the existing protein identification techniques.
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Affiliation(s)
| | - Jackson Rodrigues
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Subhash Chandra
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Nirmal Mazumder
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Alex Vitkin
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | - Krishna Kishore Mahato
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India.
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3
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Gong B, Chen W, Sit PHL, Liu XW, Qian C, Yu HQ. Multiple spectroscopic insights into the interaction mechanisms between proteins and humic acid. WATER RESEARCH 2023; 243:120424. [PMID: 37523922 DOI: 10.1016/j.watres.2023.120424] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 07/01/2023] [Accepted: 07/27/2023] [Indexed: 08/02/2023]
Abstract
Proteins are important constituents of dissolved organic matter (DOM) in aqueous environments, and their interaction with humic acid (HA), another key component of DOM, substantially affects the environmental behaviors of DOM. In this work, the interaction mechanisms between tryptophan-containing proteins and HA were systematically investigated using multiple molecular spectroscopic approaches. The fluorescence quenching tests indicate that bovine serum albumin (BSA) was more readily quenched by HA and the coexisting phenolic, carboxyl, and quinone groups in HA contributed to this process significantly. By comparison, the fluorescence of L-tryptophan (L-Trp) was more stable under the same conditions. Furthermore, with multiple groups in HA, static quenching with the binding constants and the number of sites were calculated in the protein-HA and L-Trp-HA mixtures. In addition, the differential fluorescence spectra, UV‒Vis spectra, and two-dimensional correlation spectroscopy results confirmed that L-tryptophan amino acid could indeed form a complex with HA, while did not lead to fluorescence quenching. Finally, the molecular docking and density functional theory (DFT) simulations highlighted the contribution of multiple residues surrounding the HA groups to their interactions. The direct interaction between the tryptophan residue and HA might not be the prerequisite for the fluorescence response. Therefore, our work provides further insights into protein-HA interactions and implies other reasonable elucidations for further explanation.
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Affiliation(s)
- Bo Gong
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China; School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region, 999077, China
| | - Wei Chen
- School of Metallurgy and Environment, Central South University, Changsha, 410083, China
| | - Patrick H-L Sit
- School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region, 999077, China
| | - Xian-Wei Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Chen Qian
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.
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4
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Unveiling the Metal-Dependent Aggregation Properties of the C-terminal Region of Amyloidogenic Intrinsically Disordered Protein Isoforms DPF3b and DPF3a. Int J Mol Sci 2022; 23:ijms232315291. [PMID: 36499617 PMCID: PMC9738585 DOI: 10.3390/ijms232315291] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/24/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
Double-PHD fingers 3 (DPF3) is a BAF-associated human epigenetic regulator, which is increasingly recognised as a major contributor to various pathological contexts, such as cardiac defects, cancer, and neurodegenerative diseases. Recently, we unveiled that its two isoforms (DPF3b and DPF3a) are amyloidogenic intrinsically disordered proteins. DPF3 isoforms differ from their C-terminal region (C-TERb and C-TERa), containing zinc fingers and disordered domains. Herein, we investigated the disorder aggregation properties of C-TER isoforms. In agreement with the predictions, spectroscopy highlighted a lack of a highly ordered structure, especially for C-TERa. Over a few days, both C-TERs were shown to spontaneously assemble into similar antiparallel and parallel β-sheet-rich fibrils. Altered metal homeostasis being a neurodegeneration hallmark, we also assessed the influence of divalent metal cations, namely Cu2+, Mg2+, Ni2+, and Zn2+, on the C-TER aggregation pathway. Circular dichroism revealed that metal binding does not impair the formation of β-sheets, though metal-specific tertiary structure modifications were observed. Through intrinsic and extrinsic fluorescence, we found that metal cations differently affect C-TERb and C-TERa. Cu2+ and Ni2+ have a strong inhibitory effect on the aggregation of both isoforms, whereas Mg2+ impedes C-TERb fibrillation and, on the contrary, enhances that of C-TERa. Upon Zn2+ binding, C-TERb aggregation is also hindered, and the amyloid autofluorescence of C-TERa is remarkably red-shifted. Using electron microscopy, we confirmed that the metal-induced spectral changes are related to the morphological diversity of the aggregates. While metal-treated C-TERb formed breakable and fragmented filaments, C-TERa fibrils retained their flexibility and packing properties in the presence of Mg2+ and Zn2+ cations.
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5
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Prabhu GRD, Yang TH, Shiu RT, Witek HA, Urban PL. Scanning pH-metry for Observing Reversibility in Protein Folding. Biochemistry 2022; 61:2377-2389. [PMID: 36251331 DOI: 10.1021/acs.biochem.2c00453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One of the main factors affecting protein structure in solution is pH. Traditionally, to study pH-dependent conformational changes in proteins, the concentration of the H+ ions is adjusted manually, complicating real-time analyses, hampering dynamic pH regulation, and consequently leading to a limited number of tested pH levels. Here, we present a programmable device, a scanning pH-meter, that can automatically generate different types of pH ramps and waveforms in a solution. A feedback loop algorithm calculates the required flow rates of the acid/base titrants, allowing one, for example, to generate periodic pH sine waveforms to study the reversibility of protein folding by fluorescence spectroscopy. Interestingly, for some proteins, the fluorescence intensity profiles recorded in such a periodically oscillating pH environment display hysteretic behavior indicating an asymmetry in the sequence of the protein unfolding/refolding events, which can most likely be attributed to their distinct kinetics. Another useful application of the scanning pH-meter concerns coupling it with an electrospray ionization mass spectrometer to observe pH-induced structural changes in proteins as revealed by their varying charge-state distributions. We anticipate a broad range of applications of the scanning pH-meter developed here, including protein folding studies, determination of the optimum pH for achieving maximum fluorescence intensity, and characterization of fluorescent dyes and other synthetic materials.
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Affiliation(s)
- Gurpur Rakesh D Prabhu
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Road, Hsinchu300044, Taiwan
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu300093, Taiwan
| | - Tzu-Hsin Yang
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Road, Hsinchu300044, Taiwan
| | - Ruei-Tzung Shiu
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Road, Hsinchu300044, Taiwan
| | - Henryk A Witek
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu300093, Taiwan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu300093, Taiwan
| | - Pawel L Urban
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Road, Hsinchu300044, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101, Sec 2, Kuang-Fu Road, Hsinchu300044, Taiwan
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6
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Mignon J, Mottet D, Leyder T, Uversky VN, Perpète EA, Michaux C. Structural characterisation of amyloidogenic intrinsically disordered zinc finger protein isoforms DPF3b and DPF3a. Int J Biol Macromol 2022; 218:57-71. [PMID: 35863661 DOI: 10.1016/j.ijbiomac.2022.07.102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/08/2022] [Accepted: 07/13/2022] [Indexed: 11/05/2022]
Abstract
Double PHD fingers 3 (DPF3) is a zinc finger protein, found in the BAF chromatin remodelling complex, and is involved in the regulation of gene expression. Two DPF3 isoforms have been identified, respectively named DPF3b and DPF3a. Very limited structural information is available for these isoforms, and their specific functionality still remains poorly studied. In a previous work, we have demonstrated the first evidence of DPF3a being a disordered protein sensitive to amyloid fibrillation. Intrinsically disordered proteins (IDPs) lack a defined tertiary structure, existing as a dynamic conformational ensemble, allowing them to act as hubs in protein-protein interaction networks. In the present study, we have more thoroughly characterised DPF3a in vitro behaviour, as well as unravelled and compared the structural properties of the DPF3b isoform, using an array of predictors and biophysical techniques. Predictions, spectroscopy, and dynamic light scattering have revealed a high content in disorder: prevalence of random coil, aromatic residues partially to fully exposed to the solvent, and large hydrodynamic diameters. DPF3a appears to be more disordered than DPF3b, and exhibits more expanded conformations. Furthermore, we have shown that they both time-dependently aggregate into amyloid fibrils, as revealed by typical circular dichroism, deep-blue autofluorescence, and amyloid-dye binding assay fingerprints. Although spectroscopic and microscopic analyses have unveiled that they share a similar aggregation pathway, DPF3a fibrillates at a faster rate, likely through reordering of its C-terminal domain.
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Affiliation(s)
- Julien Mignon
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Institute of Structured Matter (NISM), University of Namur, Namur, Belgium; Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
| | - Denis Mottet
- University of Liège, GIGA-Molecular Biology of Diseases, Gene Expression and Cancer Laboratory, B34, Avenue de l'Hôpital, 4000 Liège, Belgium.
| | - Tanguy Leyder
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium.
| | - Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States.
| | - Eric A Perpète
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium; Institute of Life, Earth and Environment (ILEE), University of Namur, Namur, Belgium.
| | - Catherine Michaux
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium; Namur Institute of Structured Matter (NISM), University of Namur, Namur, Belgium; Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
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7
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Mukunda DC, Joshi VK, Chandra S, Siddaramaiah M, Rodrigues J, Gadag S, Nayak UY, Mazumder N, Satyamoorthy K, Mahato KK. Probing nonenzymatic glycation of proteins by deep ultraviolet light emitting diode induced autofluorescence. Int J Biol Macromol 2022; 213:279-296. [DOI: 10.1016/j.ijbiomac.2022.05.151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 03/25/2022] [Accepted: 05/22/2022] [Indexed: 01/03/2023]
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8
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Mukunda DC, Rodrigues J, Joshi VK, Raghushaker CR, Mahato KK. A comprehensive review on LED-induced fluorescence in diagnostic pathology. Biosens Bioelectron 2022; 209:114230. [PMID: 35421670 DOI: 10.1016/j.bios.2022.114230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 03/19/2022] [Accepted: 03/25/2022] [Indexed: 11/02/2022]
Abstract
Sensitivity, specificity, mobility, and affordability are important criteria to consider for developing diagnostic instruments in common use. Fluorescence spectroscopy has been demonstrating substantial potential in the clinical diagnosis of diseases and evaluating the underlying causes of pathogenesis. A higher degree of device integration with appropriate sensitivity and reasonable cost would further boost the value of the fluorescence techniques in clinical diagnosis and aid in the reduction of healthcare expenses, which is a key economic concern in emerging markets. Light-emitting diodes (LEDs), which are inexpensive and smaller are attractive alternatives to conventional excitation sources in fluorescence spectroscopy, are gaining a lot of momentum in the development of affordable, compact analytical instruments of clinical relevance. The commercial availability of a broad range of LED wavelengths (255-4600 nm) has opened up new avenues for targeting a wide range of clinically significant molecules (both endogenous and exogenous), thereby diagnosing a range of clinical illnesses. As a result, we have specifically examined the uses of LED-induced fluorescence (LED-IF) in preclinical and clinical evaluations of pathological conditions, considering the present advancements in the field.
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Affiliation(s)
| | - Jackson Rodrigues
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Vijay Kumar Joshi
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Chandavalli Ramappa Raghushaker
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Krishna Kishore Mahato
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India.
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9
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O'Neil PT, Vasquez-Montes V, Swint-Kruse L, Baldwin MR, Ladokhin AS. Spectroscopic evidence of tetanus toxin translocation domain bilayer-induced refolding and insertion. Biophys J 2021; 120:4763-4776. [PMID: 34555358 PMCID: PMC8595737 DOI: 10.1016/j.bpj.2021.09.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/03/2021] [Accepted: 09/16/2021] [Indexed: 12/21/2022] Open
Abstract
Tetanus neurotoxin (TeNT) is an A-B toxin with three functional domains: endopeptidase, translocation (HCT), and receptor binding. Endosomal acidification triggers HCT to interact with and insert into the membrane, translocating the endopeptidase across the bilayer. Although the function of HCT is well defined, the mechanism by which it accomplishes this task is unknown. To gain insight into the HCT membrane interaction on both local and global scales, we utilized an isolated, beltless HCT variant (bHCT), which retained the ability to release potassium ions from vesicles. To examine which bHCT residues interact with the membrane, we widely sampled the surface of bHCT using 47 single-cysteine variants labeled with the environmentally sensitive fluorophore NBD. At neutral pH, no interaction was observed for any variant. In contrast, all NBD-labeled positions reported environmental change in the presence of acidic pH and membranes containing anionic lipids. We then examined the conformation of inserted bHCT using circular dichroism and intrinsic fluorescence. Upon entering the membrane, bHCT retained predominantly α-helical secondary structure, whereas the tertiary structure exhibited substantial refolding. The use of lipid-attached quenchers revealed that at least one of the three tryptophan residues penetrated deep into the hydrocarbon core of the membrane, suggesting formation of a bHCT transmembrane conformation. The possible conformational topology was further explored with the hydropathy analysis webtool MPEx, which identified a large, potential α-helical transmembrane region. Altogether, the spectroscopic evidence supports a model in which, upon acidification, the majority of TeNT bHCT entered the membrane with a concurrent change in tertiary structure.
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Affiliation(s)
- Pierce T O'Neil
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Victor Vasquez-Montes
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Liskin Swint-Kruse
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Michael R Baldwin
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri
| | - Alexey S Ladokhin
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas.
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10
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Liu Z, Guo Z, Wu D, Fei X, Ei-Seedi HR, Wang C. High-pressure homogenization influences the functional properties of protein from oyster (Crassostrea gigas). Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.112107] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Zaharias S, Zhang Z, Davis K, Fargason T, Cashman D, Yu T, Zhang J. Intrinsically disordered electronegative clusters improve stability and binding specificity of RNA-binding proteins. J Biol Chem 2021; 297:100945. [PMID: 34246632 PMCID: PMC8348266 DOI: 10.1016/j.jbc.2021.100945] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/28/2021] [Accepted: 07/07/2021] [Indexed: 11/25/2022] Open
Abstract
RNA-binding proteins play crucial roles in various cellular functions and contain abundant disordered protein regions. The disordered regions in RNA-binding proteins are rich in repetitive sequences, such as poly-K/R, poly-N/Q, poly-A, and poly-G residues. Our bioinformatic analysis identified a largely neglected repetitive sequence family we define as electronegative clusters (ENCs) that contain acidic residues and/or phosphorylation sites. The abundance and length of ENCs exceed other known repetitive sequences. Despite their abundance, the functions of ENCs in RNA-binding proteins are still elusive. To investigate the impacts of ENCs on protein stability, RNA-binding affinity, and specificity, we selected one RNA-binding protein, the ribosomal biogenesis factor 15 (Nop15), as a model. We found that the Nop15 ENC increases protein stability and inhibits nonspecific RNA binding, but minimally interferes with specific RNA binding. To investigate the effect of ENCs on sequence specificity of RNA binding, we grafted an ENC to another RNA-binding protein, Ser/Arg-rich splicing factor 3. Using RNA Bind-n-Seq, we found that the engineered ENC inhibits disparate RNA motifs differently, instead of weakening all RNA motifs to the same extent. The motif site directly involved in electrostatic interaction is more susceptible to the ENC inhibition. These results suggest that one of functions of ENCs is to regulate RNA binding via electrostatic interaction. This is consistent with our finding that ENCs are also overrepresented in DNA-binding proteins, whereas underrepresented in halophiles, in which nonspecific nucleic acid binding is inhibited by high concentrations of salts.
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Affiliation(s)
- Steve Zaharias
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kenneth Davis
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Derek Cashman
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee, USA
| | - Tao Yu
- Department of Chemistry, University of North Dakota, Grand Forks, North Dakota, USA
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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12
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Asami H, Kawauchi N, Kohno JY. Gas-phase hydration of the lysozyme ion produced by infrared-laser ablation of a droplet beam studied by photodissociation and fluorescence spectroscopy. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4620. [PMID: 32721078 DOI: 10.1002/jms.4620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
Biomolecules function in an aqueous environment. Elucidation of the hydration structures of biomolecules is hence important to understand their functions. Here, we investigated the hydration structure of lysozyme (Lys) in the gas phase by photodissociation and fluorescence spectroscopy in combination with droplet-beam laser ablation mass spectrometry. We found that water molecules are held inside and on the surface of the Lys molecule, and the hydration structure around the tryptophan residue changes by photoexcitation. This study provides a novel method to observe the hydration structures of large biomolecules at the molecular level.
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Affiliation(s)
- Hiroya Asami
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
| | - Norishi Kawauchi
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
| | - Jun-Ya Kohno
- Department of Chemistry, Faculty of Science, Gakushuin University, Tokyo, Japan
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13
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Wang Y, Ye Z, Li J, Zhang Y, Guo Y, Cheng JH. Effects of dielectric barrier discharge cold plasma on the activity, structure and conformation of horseradish peroxidase (HRP) and on the activity of litchi peroxidase (POD). Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.111078] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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14
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Xiong Y, Shi C, Li L, Tang Y, Zhang X, Liao S, Zhang B, Sun C, Ren C. A review on recent advances in amino acid and peptide-based fluorescence and its potential applications. NEW J CHEM 2021. [DOI: 10.1039/d1nj02230j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Fluorescence is widely used to detect functional groups and ions, and peptides are used in various fields due to their excellent biological activity.
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Affiliation(s)
- Yingshuo Xiong
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Changxin Shi
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Lingyi Li
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Yuanhan Tang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Xin Zhang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Sisi Liao
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Beibei Zhang
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Changmei Sun
- School of Chemistry and Materials Science, Ludong University, Yantai 264025, China
| | - Chunguang Ren
- Yantai Institute of Materia Medica, Yantai 264000, China
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15
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Wang Y, Liu Y, Ma L, Yang L, Cong P, Lan H, Xue C, Xu J. Co-oxidation of Antarctic krill oil with whey protein and myofibrillar protein in oil-in-water emulsions. J Food Sci 2020; 85:3797-3805. [PMID: 33067851 DOI: 10.1111/1750-3841.15500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 08/30/2020] [Accepted: 09/24/2020] [Indexed: 11/28/2022]
Abstract
Antarctic krill oil (AKO) is usually encapsulated by the protein materials, enhancing its oxidative stability. Proteins exhibit immense effect on lipid oxidation and induce protein-lipid co-oxidation. This study aimed at elucidating the co-oxidation mechanism of AKO and whey protein (WP) or myofibrillar protein (MP) in oil-in-water emulsions. The estimations of malondialdehyde (MDA) content, phospholipid molecular species, and pyrrole content resulted in increased and decreased oxidation rate of AKO (especially phosphatidylethanolamine) by WP and MP, respectively. Meanwhile, protein concentration, sulfhydryl content, the loss of tryptophan fluorescence intensity, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis results demonstrated that AKO promoted WP oxidation but inhibited MP oxidation. Further, the antioxidative abilities of seven common antioxidants were evaluated. Ascorbyl palmitate showed the most substantial antioxidative effect for both AKO and proteins (about 70% decrease of MDA content and 30% decrease of the decrease ratio of tryptophan fluorescence intensity). This finding supported that different proteins could exhibit different pro/anti-oxidative effects on lipid oxidation, especially for marine lipids abundant in phospholipids and polyunsaturated fatty acids. Besides, MP could also act as antioxidant in MP AKO emulsions, further extending its application from traditional surfactants. PRACTICAL APPLICATION: AKO is usually encapsulated by the protein materials, enhancing its oxidative stability. The results demonstrated MP could inhibit AKO oxidation, and vice versa, especially when ascorbyl palmitate was added at the same time. As a result, this finding explored a new potential wall material with antioxidative ability for the encapsulated products of AKO.
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Affiliation(s)
- Yuliu Wang
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Yanzi Liu
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Lei Ma
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Lu Yang
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Peixu Cong
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Haohui Lan
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
| | - Changhu Xue
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China.,Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, 266235, People's Republic of China
| | - Jie Xu
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, People's Republic of China
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16
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Vattepu R, Klausmeyer RA, Ayella A, Yadav R, Dille JT, Saiz SV, Beck MR. Conserved tryptophan mutation disrupts structure and function of immunoglobulin domain revealing unusual tyrosine fluorescence. Protein Sci 2020; 29:2062-2074. [PMID: 32797644 DOI: 10.1002/pro.3929] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 12/27/2022]
Abstract
Immunoglobulin (Ig) domains are the most prevalent protein domain structure and share a highly conserved folding pattern; however, this structural family of proteins is also the most diverse in terms of biological roles and tissue expression. Ig domains vary significantly in amino acid sequence but share a highly conserved tryptophan in the hydrophobic core of this beta-stranded protein. Palladin is an actin binding and bundling protein that has five Ig domains and plays an important role in normal cell adhesion and motility. Mutation of the core tryptophan in one Ig domain of palladin has been identified in a pancreatic cancer cell line, suggesting a crucial role for this sole tryptophan in palladin Ig domain structure, stability, and function. We found that actin binding and bundling was not completely abolished with removal of this tryptophan despite a partially unfolded structure and significantly reduced stability of the mutant Ig domain as shown by circular dichroism investigations. In addition, this mutant palladin domain displays a tryptophan-like fluorescence attributed to an anomalous tyrosine emission at 341 nm. Our results indicate that this emission originates from a tyrosinate that may be formed in the excited ground state by proton transfer to a nearby aspartic acid residue. Furthermore, this study emphasizes the importance of tryptophan in protein structural stability and illustrates how tyrosinate emission contributions may be overlooked during the interpretation of the fluorescence properties of proteins.
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Affiliation(s)
- Ravi Vattepu
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | | | - Allan Ayella
- Chemistry Department, Wichita State University, Wichita, Kansas, USA.,Chemistry Department, Washburn University, Topeka, Kansas, USA
| | - Rahul Yadav
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Joseph T Dille
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Stan V Saiz
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Moriah R Beck
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
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17
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Zheng H, Zheng YC, Cui Y, Zhu JJ, Zhong JY. Study on effects of co-solvents on the structure of DhaA by molecular dynamics simulation. J Biomol Struct Dyn 2020; 39:5999-6007. [PMID: 32696722 DOI: 10.1080/07391102.2020.1796801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
With the increasing application of enzymes in various research fields, the choices of co-solvents in enzymatic preparations which directly related to the catalytic activity have been attracted attention. Thus, researching on the stabilization or destabilization behaviors of enzymes in different solvents is extremely essential. In this study, the structural changes of DhaA in two typical aprotic co-solvents (acetonitrile and tetrahydrofuran) were firstly investigated by molecular dynamics (MD) simulation. The simulation results revealed the strong van der Waals force between co-solvents and DhaA which could induce the structural change of enzyme. Interestingly, the differences of molecular size and the electrostatic force with enzyme of two co-solvents led to quite different influences on DhaA. As for acetonitrile, solvent molecules could penetrate into the catalytic site of DhaA which promoted by the electrostatic interaction. On the contrary, tetrahydrofuran molecules were mainly distributed around the catalytic site due to the relative weak electrostatic interaction and steric resistance effect. It can be concluded that different co-solvent can affect the key domains, substrate pathway and catalytic pocket of DhaA.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- He Zheng
- State Key Laboratory of NBC Protection for Civilian, Beijing, China
| | - Yong-Chao Zheng
- State Key Laboratory of NBC Protection for Civilian, Beijing, China
| | - Yan Cui
- State Key Laboratory of NBC Protection for Civilian, Beijing, China
| | - Jian-Jun Zhu
- State Key Laboratory of NBC Protection for Civilian, Beijing, China
| | - Jin-Yi Zhong
- State Key Laboratory of NBC Protection for Civilian, Beijing, China
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18
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Gleason PR, Kelly PI, Grisingher DW, Mills JH. An intrinsic FRET sensor of protein-ligand interactions. Org Biomol Chem 2020; 18:4079-4084. [PMID: 32427252 PMCID: PMC7313717 DOI: 10.1039/d0ob00793e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe an approach for the development of fluorescent sensors of metabolite binding in which a genetically encoded fluorescent non-canonical amino acid (fNCAA) containing a 7-hydroxycoumarin moiety (7-HCAA) forms a FRET pair with native tryptophan residues. Although previous studies demonstrated the potential for using 7-HCAA as an acceptor for tryptophan, this approach has not yet been explored within a single protein containing multiple tryptophan residues. A structure-based analysis of a hexokinase enzyme with multiple native tryptophan residues identified glutamate 50 as a potential site of 7-HCAA incorporation; Glu50 moves closer to the native tryptophans upon substrate binding. Substitution of 7-HCAA at residue 50 led to an increase in FRET efficiency in the presence of the substrate; this effect was not observed in a control protein where no change in distance between 7-HCAA and the native tryptophans occurs on substrate binding. This system was then used to directly observe differences in binding affinity of the hexokinase that occur at a number of pH values. Our approach builds on previous research in that it eliminates the need for the incorporation of multiple fNCAAs or fluorescent labels within a target protein and can be used to study substrate binding with native ligands. As such, it serves to expand the versatility of FRET-based techniques.
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Affiliation(s)
- Patrick R Gleason
- School of Molecular Sciences and The Biodesign Center for Molecular Design and Biomimetics, Arizona State University, Tempe, AZ 85287, USA.
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19
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Carvalho Bertozo L, Fernandes AJFC, Yoguim MI, Bolean M, Ciancaglini P, Ximenes VF. Entropy‐driven binding of octyl gallate in albumin: Failure in the application of temperature effect to distinguish dynamic and static fluorescence quenching. J Mol Recognit 2020; 33:e2840. [DOI: 10.1002/jmr.2840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/25/2020] [Accepted: 02/10/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Luiza Carvalho Bertozo
- Department of Chemistry, Faculty of SciencesUNESP—São Paulo State University São Paulo Brazil
| | - Ana J. F. C. Fernandes
- Department of Chemistry, Faculty of SciencesUNESP—São Paulo State University São Paulo Brazil
| | - Maurício I. Yoguim
- Department of Chemistry, Faculty of SciencesUNESP—São Paulo State University São Paulo Brazil
| | - Maytê Bolean
- Department of Chemistry, Faculty of Philosophy, Sciences and Letters at Ribeirão PretoUniversity of São Paulo Ribeirão Preto SP Brazil
| | - Pietro Ciancaglini
- Department of Chemistry, Faculty of Philosophy, Sciences and Letters at Ribeirão PretoUniversity of São Paulo Ribeirão Preto SP Brazil
| | - Valdecir F. Ximenes
- Department of Chemistry, Faculty of SciencesUNESP—São Paulo State University São Paulo Brazil
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20
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Importance of Hypericin-Bcl2 interactions for biological effects at subcellular levels. Photodiagnosis Photodyn Ther 2019; 28:38-52. [PMID: 31430575 DOI: 10.1016/j.pdpdt.2019.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/18/2019] [Accepted: 08/12/2019] [Indexed: 02/06/2023]
Abstract
Hypericin (Hyp) is a naturally occurring compound used as photosensitizer in photodynamic therapy and diagnosis. Recently, we have shown that Hyp presence alone, without illumination, resulted in substantial biological effects at several sub-cellular levels. Hyp induced changes in cellular ultrastructure, mitochondria function and metabolism, and distribution of Bcl2 proteins in malignant and non-malignant cells. The molecular mechanisms that underlie Hyp light-independent effects are still elusive. We have hypothesized that Bcl2-Hyp interactions might be one possible mechanism. We performed molecular docking studies to determine the Hyp-Bcl2 interaction profile. Based on the interaction profiles small Bcl2 peptide segments were selected for further study. We designed small peptides corresponding to Bcl2 BH3 and BH1 domains and tested the binding of Hyp and Bcl2 known inhibitor, ABT263, to the peptides in computer modeling and in vitro binding studies. We employed endogenous tryptophan and tyrosine in the BH3 and BH1 peptides, respectively, and their fluorescent properties to show interaction with Hyp and ABT263. Overall, our results indicate that Hyp can interact with Bcl2 protein at its BH3-BH1 hydrophobic groove, and this interaction may trigger changes in intracellular distribution of Bcl2 proteins. In addition, our computer modeling results suggest that Hyp also interacts with other anti-apoptotic members of Bcl2 family similar to the known BH3 mimetics. Our findings are novel and might contribute to understanding Hyp light-independent effects. In addition, they may substantiate the therapeutic use of Hyp as a BH3 mimetic molecule to enhance other cancer treatments.
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