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Gulati K, Adachi T. Profiling to Probing: Atomic force microscopy to characterize nano-engineered implants. Acta Biomater 2023; 170:15-38. [PMID: 37562516 DOI: 10.1016/j.actbio.2023.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 07/26/2023] [Accepted: 08/03/2023] [Indexed: 08/12/2023]
Abstract
Surface modification of implants in the nanoscale or implant nano-engineering has been recognized as a strategy for augmenting implant bioactivity and achieving long-term implant success. Characterizing and optimizing implant characteristics is crucial to achieving desirable effects post-implantation. Modified implant enables tailored, guided and accelerated tissue integration; however, our understanding is limited to multicellular (bulk) interactions. Finding the nanoscale forces experienced by a single cell on nano-engineered implants will aid in predicting implants' bioactivity and engineering the next generation of bioactive implants. Atomic force microscope (AFM) is a unique tool that enables surface characterization and understanding of the interactions between implant surface and biological tissues. The characterization of surface topography using AFM to gauge nano-engineered implants' characteristics (topographical, mechanical, chemical, electrical and magnetic) and bioactivity (adhesion of cells) is presented. A special focus of the review is to discuss the use of single-cell force spectroscopy (SCFS) employing AFM to investigate the minute forces involved with the adhesion of a single cell (resident tissue cell or bacterium) to the surface of nano-engineered implants. Finally, the research gaps and future perspectives relating to AFM-characterized current and emerging nano-engineered implants are discussed towards achieving desirable bioactivity performances. This review highlights the use of advanced AFM-based characterization of nano-engineered implant surfaces via profiling (investigating implant topography) or probing (using a single cell as a probe to study precise adhesive forces with the implant surface). STATEMENT OF SIGNIFICANCE: Nano-engineering is emerging as a surface modification platform for implants to augment their bioactivity and achieve favourable treatment outcomes. In this extensive review, we closely examine the use of Atomic Force Microscopy (AFM) to characterize the properties of nano-engineered implant surfaces (topography, mechanical, chemical, electrical and magnetic). Next, we discuss Single-Cell Force Spectroscopy (SCFS) via AFM towards precise force quantification encompassing a single cell's interaction with the implant surface. This interdisciplinary review will appeal to researchers from the broader scientific community interested in implants and cell adhesion to implants and provide an improved understanding of the surface characterization of nano-engineered implants.
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Affiliation(s)
- Karan Gulati
- Institute for Life and Medical Sciences, Kyoto University, Sakyo, Kyoto 606-8507, Japan; The University of Queensland, School of Dentistry, Herston QLD 4006, Australia.
| | - Taiji Adachi
- Institute for Life and Medical Sciences, Kyoto University, Sakyo, Kyoto 606-8507, Japan
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Meinhold S, Bauer D, Huber J, Merkel U, Weißl A, Žoldák G, Rief M. An Active, Ligand-Responsive Pulling Geometry Reports on Internal Signaling between Subdomains of the DnaK Nucleotide-Binding Domain in Single-Molecule Mechanical Experiments. Biochemistry 2019; 58:4744-4750. [PMID: 31120736 DOI: 10.1021/acs.biochem.9b00155] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Single-molecule mechanical experiments have proven to be ideal tools for probing the energetics and mechanics of large proteins and domains. In this paper, we investigate the nucleotide-dependent unfolding mechanics of the nucleotide-binding domain (NBD) of the Hsp70 chaperone DnaK. The NBD binds ADP or ATP in the binding cleft formed by lobe I and lobe II, which consists of two subdomains each. When force is applied to the termini of the NBD, the observed unfolding forces are independent of the nucleotide state. In contrast, when force is applied across the nucleotide-binding pocket, the unfolding forces report specifically on the nucleotide-phosphate state. In this active, ligand-responsive pulling geometry, we observed a bifurcation of the unfolding pathway; the pathway proceeds either through a cooperative "coupled pathway" or through a noncooperative "uncoupled pathway". The partitioning between individual unfolding pathways can be effectively tuned by mutation or by the nucleotide exchange factor GrpE, i.e., by the factors affecting the strength of the lobe I-lobe II interactions within the native NBD. These experiments provide important insight into the molecular origin of the internal signaling between the subdomains of the nucleotide-binding domain of Hsp70 proteins and how signals are efficiently transferred inside the protein molecule.
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Affiliation(s)
- Sarah Meinhold
- Physik Department E22 , Technische Universität München , 85748 Garching , Germany
| | - Daniela Bauer
- Physik Department E22 , Technische Universität München , 85748 Garching , Germany
| | - Jonas Huber
- Gene Center , Ludwig-Maximilians-University , 81377 Munich , Germany
| | - Ulrich Merkel
- Physik Department E22 , Technische Universität München , 85748 Garching , Germany
| | - Andreas Weißl
- Physik Department E22 , Technische Universität München , 85748 Garching , Germany
| | - Gabriel Žoldák
- Center for Interdisciplinary Biosciences , P. J. Safarik University , Technology and Innovation Park , 04154 Kosice , Slovakia
| | - Matthias Rief
- Physik Department E22 , Technische Universität München , 85748 Garching , Germany.,Munich Center for Integrated Protein Science , 81377 München , Germany
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Bönisch E, Oh YJ, Anzengruber J, Hager FF, López-Guzmán A, Zayni S, Hinterdorfer P, Kosma P, Messner P, Duda KA, Schäffer C. Lipoteichoic acid mediates binding of a Lactobacillus S-layer protein. Glycobiology 2018; 28:148-158. [PMID: 29309573 PMCID: PMC5993097 DOI: 10.1093/glycob/cwx102] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 12/06/2017] [Indexed: 01/06/2023] Open
Abstract
The Gram-positive lactic acid bacterium Lactobacillus buchneri CD034 is covered by a two-dimensional crystalline, glycoproteinaceous cell surface (S-) layer lattice. While lactobacilli are extensively exploited as cell surface display systems for applied purposes, questions about how they stick their cell wall together are remaining open. This also includes the identification of the S-layer cell wall ligand. In this study, lipoteichoic acid was isolated from the L. buchneri CD034 cell wall as a significant fraction of the bacterium's cell wall glycopolymers, structurally characterized and analyzed for its potential to mediate binding of the S-layer to the cell wall. Combined component analyses and 1D- and 2D-nuclear magnetic resonance spectroscopy (NMR) revealed the lipoteichoic acid to be composed of on average 31 glycerol-phosphate repeating units partially substituted with α-d-glucose, and with an α-d-Galp(1→2)-α-d-Glcp(1→3)-1,2-diacyl-sn-Gro glycolipid anchor. The specificity of binding between the L. buchneri CD034 S-layer protein and purified lipoteichoic acid as well as their interaction force of about 45 pN were obtained by single-molecule force spectroscopy; this value is in the range of typical ligand-receptor interactions. This study sheds light on a functional implication of Lactobacillus cell wall architecture by showing direct binding between lipoteichoic acid and the S-layer of L. buchneri CD034.
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Affiliation(s)
- Eva Bönisch
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Yoo Jin Oh
- Institute of Biophysics, Johannes-Kepler University Linz, A-4020 Linz, Austria.,Keysight Technologies Austria GmbH, A-4020 Linz, Austria
| | - Julia Anzengruber
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Fiona F Hager
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Arturo López-Guzmán
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Sonja Zayni
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Peter Hinterdorfer
- Institute of Biophysics, Johannes-Kepler University Linz, A-4020 Linz, Austria
| | - Paul Kosma
- Department of Chemistry, Institute of Organic Chemistry, Universität für Bodenkultur Wien, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul Messner
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
| | - Katarzyna A Duda
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria.,Junior Group of Allergobiochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Airway Research Center North (ARCN), German Center for Lung Research, D-23845 Borstel, Germany
| | - Christina Schäffer
- Department of NanoBiotechnology, NanoGlycobiology unit, Universität für Bodenkultur Wien, Muthgasse 11, Austria
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Zhu C, Guo G, Ma Q, Zhang F, Ma F, Liu J, Xiao D, Yang X, Sun M. Diversity in S-layers. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 123:1-15. [PMID: 27498171 DOI: 10.1016/j.pbiomolbio.2016.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/16/2016] [Accepted: 08/02/2016] [Indexed: 01/29/2023]
Abstract
Surface layers, referred simply as S-layers, are the two-dimensional crystalline arrays of protein or glycoprotein subunits on cell surface. They are one of the most common outermost envelope components observed in prokaryotic organisms (Archaea and Bacteria). Over the past decades, S-layers have become an issue of increasing interest due to their ubiquitousness, special features and functions. Substantial work in this field provides evidences of an enormous diversity in S-layers. This paper reviews and illustrates the diversity from several different aspects, involving the S-layer-carrying strains, the structure of S-layers, the S-layer proteins and genes, as well as the functions of S-layers.
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Affiliation(s)
- Chaohua Zhu
- College of Environment and Plant protection, Hainan University/Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources (Hainan University), Ministry of Education, Haikou, 570228, Hainan, PR China
| | - Gang Guo
- Haikou Experimental Station/Hainan Key Laboratory of Banana Genetic Improvement, Chinese Academy of Tropical Agricultural Sciences, Haikou, 570102, Hainan, PR China; State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, PR China
| | - Qiqi Ma
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, PR China
| | - Fengjuan Zhang
- Haikou Experimental Station/Hainan Key Laboratory of Banana Genetic Improvement, Chinese Academy of Tropical Agricultural Sciences, Haikou, 570102, Hainan, PR China
| | - Funing Ma
- Haikou Experimental Station/Hainan Key Laboratory of Banana Genetic Improvement, Chinese Academy of Tropical Agricultural Sciences, Haikou, 570102, Hainan, PR China
| | - Jianping Liu
- Division of Functional Genomics, Department of Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, Stockholm 17177, Sweden
| | - Dao Xiao
- Haikou Experimental Station/Hainan Key Laboratory of Banana Genetic Improvement, Chinese Academy of Tropical Agricultural Sciences, Haikou, 570102, Hainan, PR China
| | - Xiaolin Yang
- College of Environment and Plant protection, Hainan University/Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources (Hainan University), Ministry of Education, Haikou, 570228, Hainan, PR China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, PR China.
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Kotamarthi HC, Yadav A, Koti Ainavarapu SR. Small peptide binding stiffens the ubiquitin-like protein SUMO1. Biophys J 2015; 108:360-7. [PMID: 25606684 DOI: 10.1016/j.bpj.2014.11.3474] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 11/05/2014] [Accepted: 11/24/2014] [Indexed: 01/08/2023] Open
Abstract
Posttranslational modification by small ubiquitin-like modifiers (SUMOs), known as SUMOylation, is a key regulatory event in many eukaryotic cellular processes in which SUMOs interact with a large number of target proteins. SUMO binding motifs (SBMs) are small peptides derived from these target proteins that interact noncovalently with SUMOs and induce conformational changes. To determine the effect of SBMs on the mechanical properties of SUMO1 (the first member of the human SUMO family), we performed single-molecule force spectroscopy experiments on SUMO1/SBM complexes. The unfolding force of SUMO1 (at a pulling speed of 400 nm/s) increased from ∼ 130 pN to ∼ 170 pN upon binding to SBMs, indicating mechanical stabilization upon complexation. Pulling-speed-dependent experiments and Monte Carlo simulations measured a large decrease in distance to the unfolding transition state for SUMO1 upon SBM binding, which is by far the largest change measured for any ligand binding protein. The stiffness of SUMO1 (measured as a spring constant for the deformation response along the line joining the N- and C-termini) increased upon SBM binding from ∼ 1 N/m to ∼ 3.5 N/m. The relatively higher flexibility of ligand-free SUMO1 might play a role in accessing various conformations before binding to a target.
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Affiliation(s)
- Hema Chandra Kotamarthi
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
| | - Anju Yadav
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
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Sleytr UB, Schuster B, Egelseer E, Pum D. S-layers: principles and applications. FEMS Microbiol Rev 2014; 38:823-64. [PMID: 24483139 PMCID: PMC4232325 DOI: 10.1111/1574-6976.12063] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 01/12/2023] Open
Abstract
Monomolecular arrays of protein or glycoprotein subunits forming surface layers (S-layers) are one of the most commonly observed prokaryotic cell envelope components. S-layers are generally the most abundantly expressed proteins, have been observed in species of nearly every taxonomical group of walled bacteria, and represent an almost universal feature of archaeal envelopes. The isoporous lattices completely covering the cell surface provide organisms with various selection advantages including functioning as protective coats, molecular sieves and ion traps, as structures involved in surface recognition and cell adhesion, and as antifouling layers. S-layers are also identified to contribute to virulence when present as a structural component of pathogens. In Archaea, most of which possess S-layers as exclusive wall component, they are involved in determining cell shape and cell division. Studies on structure, chemistry, genetics, assembly, function, and evolutionary relationship of S-layers revealed considerable application potential in (nano)biotechnology, biomimetics, biomedicine, and synthetic biology.
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Affiliation(s)
- Uwe B. Sleytr
- Institute of BiophysicsDepartment of NanobiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Bernhard Schuster
- Institute of Synthetic BiologyDepartment of NanobiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Eva‐Maria Egelseer
- Institute of BiophysicsDepartment of NanobiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Dietmar Pum
- Institute of BiophysicsDepartment of NanobiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
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7
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Pillet F, Chopinet L, Formosa C, Dague E. Atomic Force Microscopy and pharmacology: from microbiology to cancerology. Biochim Biophys Acta Gen Subj 2013; 1840:1028-50. [PMID: 24291690 DOI: 10.1016/j.bbagen.2013.11.019] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 11/18/2013] [Accepted: 11/20/2013] [Indexed: 02/06/2023]
Abstract
BACKGROUND Atomic Force Microscopy (AFM) has been extensively used to study biological samples. Researchers take advantage of its ability to image living samples to increase our fundamental knowledge (biophysical properties/biochemical behavior) on living cell surface properties, at the nano-scale. SCOPE OF REVIEW AFM, in the imaging modes, can probe cells morphological modifications induced by drugs. In the force spectroscopy mode, it is possible to follow the nanomechanical properties of a cell and to probe the mechanical modifications induced by drugs. AFM can be used to map single molecule distribution at the cell surface. We will focus on a collection of results aiming at evaluating the nano-scale effects of drugs, by AFM. Studies on yeast, bacteria and mammal cells will illustrate our discussion. Especially, we will show how AFM can help in getting a better understanding of drug mechanism of action. MAJOR CONCLUSIONS This review demonstrates that AFM is a versatile tool, useful in pharmacology. In microbiology, it has been used to study the drugs fighting Candida albicans or Pseudomonas aeruginosa. The major conclusions are a better understanding of the microbes' cell wall and of the drugs mechanism of action. In cancerology, AFM has been used to explore the effects of cytotoxic drugs or as an innovative diagnostic technology. AFM has provided original results on cultured cells, cells extracted from patient and directly on patient biopsies. GENERAL SIGNIFICANCE This review enhances the interest of AFM technologies for pharmacology. The applications reviewed range from microbiology to cancerology.
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Affiliation(s)
- Flavien Pillet
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France
| | - Louise Chopinet
- CNRS, IPBS-UMR 5089, BP64182, 205 route de Narbonne, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France
| | - Cécile Formosa
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France; CNRS, UMR 7565, SRSMC, Vandoeuvre-lès-Nancy, France; Université de Lorraine, UMR 7565, Faculté de Pharmacie, Nancy, France
| | - Etienne Dague
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France; CNRS; ITAV-USR 3505; F31106 Toulouse, France.
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8
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Moo E, Amrein M, Epstein M, Duvall M, Abu Osman N, Pingguan-Murphy B, Herzog W. The properties of chondrocyte membrane reservoirs and their role in impact-induced cell death. Biophys J 2013; 105:1590-600. [PMID: 24094400 PMCID: PMC3822719 DOI: 10.1016/j.bpj.2013.08.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 07/12/2013] [Accepted: 08/26/2013] [Indexed: 02/01/2023] Open
Abstract
Impact loading of articular cartilage causes extensive chondrocyte death. Cell membranes have a limited elastic range of 3-4% strain but are protected from direct stretch during physiological loading by their membrane reservoir, an intricate pattern of membrane folds. Using a finite-element model, we suggested previously that access to the membrane reservoir is strain-rate-dependent and that during impact loading, the accessible membrane reservoir is drastically decreased, so that strains applied to chondrocytes are directly transferred to cell membranes, which fail when strains exceed 3-4%. However, experimental support for this proposal is lacking. The purpose of this study was to measure the accessible membrane reservoir size for different membrane strain rates using membrane tethering techniques with atomic force microscopy. We conducted atomic force spectroscopy on isolated chondrocytes (n = 87). A micron-sized cantilever was used to extract membrane tethers from cell surfaces at constant pulling rates. Membrane tethers could be identified as force plateaus in the resulting force-displacement curves. Six pulling rates were tested (1, 5, 10, 20, 40, and 80 μm/s). The size of the membrane reservoir, represented by the membrane tether surface areas, decreased exponentially with increasing pulling rates. The current results support our theoretical findings that chondrocytes exposed to impact loading die because of membrane ruptures caused by high tensile membrane strain rates.
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Affiliation(s)
- Eng Kuan Moo
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada
| | - Matthias Amrein
- Departments of Cell Biology and Anatomy and Pathology and Laboratory Medicine, Faculty of Medicine, The University of Calgary, Calgary, Alberta, Canada
| | - Marcelo Epstein
- Department of Mechanical and Manufacturing Engineering, The University of Calgary, Calgary, Alberta, Canada
| | - Mike Duvall
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada
| | - Noor Azuan Abu Osman
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Belinda Pingguan-Murphy
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada
- Department of Mechanical and Manufacturing Engineering, The University of Calgary, Calgary, Alberta, Canada
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Agglutinating secretory IgA preserves intestinal epithelial cell integrity during apical infection by Shigella flexneri. Infect Immun 2013; 81:3027-34. [PMID: 23753631 DOI: 10.1128/iai.00303-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Shigella flexneri, by invading intestinal epithelial cells (IECs) and inducing inflammatory responses of the colonic mucosa, causes bacillary dysentery. Although M cells overlying Peyer's patches are commonly considered the primary site of entry of S. flexneri, indirect evidence suggests that bacteria can also use IECs as a portal of entry to the lamina propria. Passive delivery of secretory IgA (SIgA), the major immunoglobulin secreted at mucosal surfaces, has been shown to protect rabbits from experimental shigellosis, but no information exists as to its molecular role in maintaining luminal epithelial integrity. We have established that the interaction of virulent S. flexneri with the apical pole of a model intestinal epithelium consisting of polarized Caco-2 cell monolayers resulted in the progressive disruption of the tight junction network and actin depolymerization, eventually resulting in cell death. The lipopolysaccharide (LPS)-specific agglutinating SIgAC5 monoclonal antibody (MAb), but not monomeric IgAC5 or IgGC20 MAbs of the same specificity, achieved protective functions through combined mechanisms, including limitation of the interaction between S. flexneri and epithelial cells, maintenance of the tight junction seal, preservation of the cell morphology, reduction of NF-κB nuclear translocation, and inhibition of proinflammatory mediator secretion. Our results add to the understanding of the function of SIgA-mediated immune exclusion by identifying a mode of action whereby the formation of immune complexes translates into maintenance of the integrity of epithelial cells lining the mucosa. This novel mechanism of protection mediated by SIgA is important to extend the arsenal of effective strategies to fight against S. flexneri mucosal invasion.
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Dorobantu LS, Goss GG, Burrell RE. Atomic force microscopy: A nanoscopic view of microbial cell surfaces. Micron 2012; 43:1312-22. [DOI: 10.1016/j.micron.2012.05.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/26/2012] [Accepted: 05/11/2012] [Indexed: 11/28/2022]
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11
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Taniguchi Y, Kawakami M. Variation in the mechanical unfolding pathway of p53DBD induced by interaction with p53 N-terminal region or DNA. PLoS One 2012; 7:e49003. [PMID: 23145047 PMCID: PMC3493487 DOI: 10.1371/journal.pone.0049003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 10/03/2012] [Indexed: 12/04/2022] Open
Abstract
The tumor suppressor p53 plays a crucial role in the cell cycle checkpoints, DNA repair, and apoptosis. p53 consists of a natively unfolded N-terminal region (NTR), central DNA binding domain (DBD), C-terminal tetramerization domain, and regulatory region. In this paper, the interactions between the DBD and the NTR, and between the DBD and DNA were investigated by measuring changes in the mechanical unfolding trajectory of the DBD using atomic force microscopy (AFM)-based single molecule force spectroscopy. In the absence of DNA, the DBD (94–293, 200 amino acids (AA)) showed two different mechanical unfolding patterns. One indicated the existence of an unfolding intermediate consisting of approximately 60 AA, and the other showed a 100 AA intermediate. The DBD with the NTR did not show such unfolding patterns, but heterogeneous unfolding force peaks were observed. Of the heterogeneous patterns, we observed a high frequency of force peaks indicating the unfolding of a domain consisting of 220 AA, which is apparently larger than that of a sole DBD. This observation implies that a part of NTR binds to the DBD, and the mechanical unfolding happens not solely on the DBD but also accompanying a part of NTR. When DNA is bound, the mechanical unfolding trajectory of p53NTR+DBD showed a different pattern from that without DNA. The pattern was similar to that of the DBD alone, but two consecutive unfolding force peaks corresponding to 60 and 100 AA sub-domains were observed. These results indicate that interactions with the NTR or DNA alter the mechanical stability of DBD and result in drastic changes in the mechanical unfolding trajectory of the DBD.
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Affiliation(s)
- Yukinori Taniguchi
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa, Japan
| | - Masaru Kawakami
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa, Japan
- * E-mail:
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12
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Upadhyayula S, Quinata T, Bishop S, Gupta S, Johnson NR, Bahmani B, Bozhilov K, Stubbs J, Jreij P, Nallagatla P, Vullev VI. Coatings of polyethylene glycol for suppressing adhesion between solid microspheres and flat surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5059-69. [PMID: 22364506 DOI: 10.1021/la300545v] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This article describes the development and the examination of surface coatings that suppress the adhesion between glass surfaces and polymer microspheres. Superparamagnetic doping allowed for exerting magnetic forces on the microbeads. The carboxyl functionalization of the polymer provided the means for coating the beads with polyethylene glycol (PEG) with different molecular weight. Under gravitational force, the microbeads settled on glass surfaces with similar polymer coatings. We examined the efficacy of removing the beads from the glass surfaces by applying a pulling force of ~1.2 pN. The percent beads remaining on the surface after applying the pulling force for approximately 5 s served as an indication of the adhesion propensity. Coating of PEG with molecular weight ranging between 3 and 10 kDa was essential for suppressing the adhesion. For the particular substrates, surface chemistry and aqueous media we used, coatings of 5 kDa manifested optimal suppression of adhesion: that is, only 3% of the microbeads remained on the surface after applying the pulling magnetic force. When either the glass or the beads were not PEGylated, the adhesion between them was substantial. Addition of a noncharged surfactant, TWEEN, above its critical micelle concentrations (CMCs) suppressed the adhesion between noncoated substrates. The extent of this surfactant-induced improvement of the adhesion suppression, however, did not exceed the quality of preventing the adhesion that we attained by PEGylating both substrates. In addition, the use of surfactants did not significantly improve the suppression of bead-surface adhesion when both substrates were PEGylated. These findings suggest that such surfactant additives tend to be redundant and that covalently grafted coatings of PEGs with selected chain lengths provide sufficient suppression of nonspecific interfacial interactions.
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Affiliation(s)
- Srigokul Upadhyayula
- Department of Bioengineering, University of California, Riverside, California 91521, United States
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