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Kitaguchi D, Oda T, Enomoto T, Ohara Y, Owada Y, Akashi Y, Furuta T, Yu Y, Kimura S, Kuroda Y, Kurimori K, Miyazaki Y, Furuya K, Shimomura O, Tateno H. Lectin drug conjugate therapy for colorectal cancer. Cancer Sci 2020; 111:4548-4557. [PMID: 33058342 PMCID: PMC7734164 DOI: 10.1111/cas.14687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 01/05/2023] Open
Abstract
Drug resistance represents an obstacle in colorectal cancer (CRC) treatment because of its association with poor prognosis. rBC2LCN is a lectin isolated from Burkholderia that binds cell surface glycans that have fucose moieties. Because fucosylation is enhanced in many types of cancers, this lectin could be an efficient drug carrier if CRC cells specifically present such glycans. Therefore, we examined the therapeutic efficacy and toxicity of lectin drug conjugate therapy in CRC mouse xenograft models. The affinity of rBC2LCN for human CRC cell lines HT-29, LoVo, LS174T, and DLD-1 was assessed in vitro. The cytocidal efficacy of a lectin drug conjugate, rBC2LCN-38 kDa domain of pseudomonas exotoxin A (PE38) was evaluated by MTT assay. The therapeutic effects and toxicity for each CRC cell line-derived mouse xenograft model were compared between the intervention and control groups. LS174T and DLD-1 cell lines showed a strong affinity for rBC2LCN. In the xenograft model, the tumor volume in the rBC2LCN-PE38 group was significantly reduced compared with that using control treatment alone. However, the HT-29 cell line showed weak affinity and poor therapeutic efficacy. No significant toxicities or adverse responses were observed. In conclusion, we demonstrated that rBC2LCN lectin binds CRC cells and that rBC2LCN-PE38 significantly suppresses tumor growth in vivo. In addition, the efficacy of the drug conjugate correlated with its binding affinity for each CRC cell line. These results suggest that lectin drug conjugate therapy has potential as a novel targeted therapy for CRC cell surface glycans.
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Affiliation(s)
- Daichi Kitaguchi
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Tatsuya Oda
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Tsuyoshi Enomoto
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yusuke Ohara
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yohei Owada
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yoshimasa Akashi
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Tomoaki Furuta
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yang Yu
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Sota Kimura
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yukihito Kuroda
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Ko Kurimori
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yoshihiro Miyazaki
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Kinji Furuya
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Osamu Shimomura
- Department of Gastrointestinal and Hepato‐Biliary‐Pancreatic SurgeryFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Hiroaki Tateno
- Biotechnology Research Institute for Drug DiscoveryNational Institute of Advanced Industrial Science and TechnologyTsukubaJapan
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2
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Abstract
The heme ATP-binding cassette (ABC) transporter BhuUV-T of bacterial pathogen Burkholderia cenocepacia is required to transport heme across the inner cell membrane. The current hypothesis is that the binding of two ATPs to the nucleotide-binding domains of the transporter drives the initial steps of the transport cycle in which the empty transport sites are reoriented from the cytosol to the periplasm. Molecular details are missing because the structure of a key occluded intermediate remains hypothetical. Here we perform molecular simulations to analyze the free energy surface (FES) of the first step of the reorientation, namely the transition from an open inward-facing (IF) transport site to an occluded (Occ) conformation. We have modeled the latter structure in silico in a previous study. A simple annealing procedure removes residual bias originating from non-equilibrium targeted molecular dynamics. The calculated FES reveals the role of the ATPs in inducing the IF → Occ conformational change and validates the modeled Occ conformation.
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Affiliation(s)
- Koichi Tamura
- Computational Biophysics
Research
Team, RIKEN Center for Computational Science, 6-7-1 minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Yuji Sugita
- Computational Biophysics
Research
Team, RIKEN Center for Computational Science, 6-7-1 minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory for Biomolecular Function
Simulation, RIKEN Center for Biosystems
Dynamics Research, 6-7-1
minatojima-Minamimachi,
Chuo-ku, Kobe, Hyogo 650-0047, Japan
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Sánchez-Rodríguez R, González GM, Becerril-García MA, Treviño-Rangel RDJ, Marcos-Vilchis A, González-Pedrajo B, Valvano MA, Andrade A. The BPtpA protein from Burkholderia cenocepacia belongs to a new subclass of low molecular weight protein tyrosine phosphatases. Arch Biochem Biophys 2020; 681:108277. [PMID: 31978399 DOI: 10.1016/j.abb.2020.108277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/15/2020] [Accepted: 01/17/2020] [Indexed: 11/24/2022]
Abstract
Low molecular weight protein tyrosine phosphatases (LMW-PTP) are ubiquitous enzymes found across a spectrum of genera from prokaryotes to higher eukaryotes. LMW-PTP belong to the Cys-based PTP class II protein family. Here, we show that LMW-PTP can be categorized into two different groups, referred as class II subdivision I (class II.I) and subdivision II (class II.II). Using BPtpA from the opportunistic pathogen Burkholderia cenocepacia, as a representative member of the LMW-PTP class II.I, we demonstrated that four conserved residues (W47, H48, D80, and F81) are required for enzyme function. Guided by an in silico model of BPtpA, we show that the conserved residues at α3-helix (D80 and F81) contribute to protein stability, while the other conserved residues in the W-loop (W47 and H48) likely play a role in substrate recognition. Overall, our results provide new information on LMW-PTP protein family and establish B. cenocepacia as a suitable model to investigate how substrates are recognized and sorted by these proteins.
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Affiliation(s)
- Rebeca Sánchez-Rodríguez
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología. Monterrey, Nuevo León, 64460, Mexico
| | - Gloria M González
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología. Monterrey, Nuevo León, 64460, Mexico
| | - Miguel A Becerril-García
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología. Monterrey, Nuevo León, 64460, Mexico
| | - Rogelio de J Treviño-Rangel
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología. Monterrey, Nuevo León, 64460, Mexico
| | - Arely Marcos-Vilchis
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, 70-243, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, 70-243, Mexico
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Angel Andrade
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología. Monterrey, Nuevo León, 64460, Mexico.
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Chávez-Ramírez B, Kerber-Díaz JC, Acoltzi-Conde MC, Ibarra JA, Vásquez-Murrieta MS, Estrada-de Los Santos P. Inhibition of Rhizoctonia solani RhCh-14 and Pythium ultimum PyFr-14 by Paenibacillus polymyxa NMA1017 and Burkholderia cenocepacia CACua-24: A proposal for biocontrol of phytopathogenic fungi. Microbiol Res 2020; 230:126347. [PMID: 31586859 DOI: 10.1016/j.micres.2019.126347] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/20/2019] [Accepted: 09/25/2019] [Indexed: 02/06/2023]
Abstract
Biocontrol has emerged in recent years as an alternative to pesticides. Given the importance of environmental preservation using biocontrol, in this study two antagonistic bacteria against phytopathogenic fungi were isolated and evaluated. These bacterial strains, identified as Paenibacillus polymyxa NMA1017 and Burkholderia cenocepacia CACua-24, inhibited (70 to 80%) the development of two phytopathogens of economic importance: the fungus Rhizoctonia solani RhCh-14, isolated from chili pepper, and the oomycete Pythium ultimum PyFr-14, isolated from tomato. The spectrum was not limited to the previous pathogens, but also to other phytopathogenic fungus, some bacteria and other oomycetes. Fungi-bacteria microcultures observed with optical and scanning electron microscopy revealed hyphae disintegration and pores formation. The antifungal activity was found also in the supernatant, suggesting a diffusible compound is present. Innocuous tests on tobacco leaves, blood agar, bean seed germination and in Galleria mellonella larvae showed that strain NMA1017 has the potential to be a biocontrol agent. Greenhouse experiments with bean plants inoculated with P. polymyxa exhibited the efficacy to inhibit the growth of R. solani and P. ultimum. Furthermore, P. polymyxa NMA1017 showed plant growth promotion activities, such as siderophore synthesis and nitrogen fixation which can contribute to the crop development.
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Affiliation(s)
- Belén Chávez-Ramírez
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
| | - Jeniffer Chris Kerber-Díaz
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
| | - Marí Carmen Acoltzi-Conde
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
| | - J Antonio Ibarra
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
| | - María-Soledad Vásquez-Murrieta
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
| | - Paulina Estrada-de Los Santos
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prol. Carpio y Plan de Ayala s/n, Col. Santo Tomas, C.P. 11340, Mexico City, Mexico.
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Yang DL, Hu YL, Yin ZX, Zeng GS, Li D, Zhang YQ, Xu ZH, Guan XM, Weng LX, Wang LH. Cis-2-dodecenoic Acid Mediates Its Synergistic Effect with Triazoles by Interfering with Efflux Pumps in Fluconazole-resistant Candida albicans. Biomed Environ Sci 2019; 32:199-209. [PMID: 30987694 DOI: 10.3967/bes2019.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 02/12/2019] [Indexed: 06/09/2023]
Abstract
OBJECTIVE To evaluate the synergy of the Burkholderia signaling molecule cis-2-dodecenoic acid (BDSF) and fluconazole (FLU) or itraconazole (ITRA) against two azole-resistant C. albicans clinical isolates in vitro and in vivo. METHODS Minimum inhibitory concentrations (MICs) of antibiotics against two azole-resistant C. albicans were measured by the checkerboard technique, E-test, and time-kill assay. In vivo antifungal synergy testing was performed on mice. Analysis of the relative gene expression levels of the strains was conducted by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). RESULTS BDSF showed highly synergistic effects in combination with FLU or ITRA with a fractional inhibitory concentration index of ⪕ 0.08. BDSF was not cytotoxic to normal human foreskin fibroblast cells at concentrations of up to 300 μg/mL. The qRT-PCR results showed that the combination of BDSF and FLU/ITRA significantly inhibits the expression of the efflux pump genes CDR1 and MDR1 via suppression of the transcription factors TAC1 and MRR1, respectively, when compared with FLU or ITRA alone. No dramatic difference in the mRNA expression levels of ERG1, ERG11, and UPC2 was found, which indicates that the drug combinations do not significantly interfere with UPC2-mediated ergosterol levels. In vivo experiments revealed that combination therapy can be an effective therapeutic approach to treat candidiasis. CONCLUSION The synergistic effects of BDSF and azoles may be useful as an alternative approach to control azole-resistant Candida infections.
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Affiliation(s)
- Dong Liang Yang
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China; School of Physical and Mathematical Sciences, Nanjing Tech University (NanjingTech), Nanjing 211816, Jiangsu, China
| | - Yan Ling Hu
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
| | - Zi Xin Yin
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
| | - Gui Sheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos 138673, Singapore
| | - Dan Li
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
| | - Yu Qian Zhang
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
| | - Zhen Hua Xu
- Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Xiao Ming Guan
- Department of Obstetrics & Gynecology, Baylor College of Medicine, 6651 Main Street, Suite F1050, Houston, Texas 77030, USA
| | - Li Xing Weng
- College of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
| | - Lian Hui Wang
- Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, Jiangsu, China
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6
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Horikawa T, Hung LW, Kim HB, Shaya D, Kim CY, Terwilliger TC, Yamashita E, Aoki M, Okada U, Murakami S. BpeB, a major resistance-nodulation-cell division transporter from Burkholderia cenocepacia: construct design, crystallization and preliminary structural analysis. Acta Crystallogr F Struct Biol Commun 2018; 74:710-716. [PMID: 30387776 PMCID: PMC6213979 DOI: 10.1107/s2053230x18013547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/24/2018] [Indexed: 11/11/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that infects cystic fibrosis patients, causing pneumonia and septicemia. B. cenocepacia has intrinsic antibiotic resistance against monobactams, aminoglycosides, chloramphenicol and fluoroquinolones that is contributed by a homologue of BpeB, which is a member of the resistance-nodulation-cell division (RND)-type multidrug-efflux transporters. Here, the cloning, overexpression, purification, construct design for crystallization and preliminary X-ray diffraction analysis of this BpeB homologue from B. cenocepacia are reported. Two truncation variants were designed to remove possible disordered regions based on comparative sequence and structural analysis to salvage the wild-type protein, which failed to crystallize. The 17-residue carboxyl-terminal truncation yielded crystals that diffracted to 3.6 Å resolution. The efflux function measured using minimal inhibitory concentration assays indicated that the truncation decreased, but did not eliminate, the efflux activity of the transporter.
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Affiliation(s)
- Tomonari Horikawa
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Li-Wei Hung
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Heung-Bok Kim
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - David Shaya
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Chang-Yub Kim
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Thomas C. Terwilliger
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- New Mexico Consortium, Los Alamos, NM 87544, USA
| | - Eiki Yamashita
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Maho Aoki
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Ui Okada
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Satoshi Murakami
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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7
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Owen HJ, Sun R, Ahmad A, Sedelnikova SE, Baker PJ, Thomas MS, Rice DW. TssA from Burkholderia cenocepacia: expression, purification, crystallization and crystallographic analysis. Acta Crystallogr F Struct Biol Commun 2018; 74:536-542. [PMID: 30198885 PMCID: PMC6130427 DOI: 10.1107/s2053230x18009706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/06/2018] [Indexed: 01/16/2023] Open
Abstract
TssA is a core component of the type VI secretion system, and phylogenetic analysis of TssA subunits from different species has suggested that these proteins fall into three distinct clades. Whilst representatives of two clades, TssA1 and TssA2, have been the subjects of investigation, no members of the third clade (TssA3) have been studied. Constructs of TssA from Burkholderia cenocepacia, a representative of clade 3, were expressed, purified and subjected to crystallization trials. Data were collected from crystals of constructs of the N-terminal and C-terminal domains. Analysis of the data from the crystals of these constructs and preliminary structure determination indicates that the C-terminal domain forms an assembly of 32 subunits in D16 symmetry, whereas the N-terminal domain is not involved in subunit assocation.
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Affiliation(s)
- Hayley J. Owen
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, England
| | - Ruyue Sun
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, England
| | - Asma Ahmad
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, England
| | - Svetlana E. Sedelnikova
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, England
| | - Patrick J. Baker
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, England
| | - Mark S. Thomas
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, England
| | - David W. Rice
- Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Western Bank, Sheffield S10 2TN, England
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Sturiale L, Palmigiano A, Silipo A, Knirel YA, Anisimov AP, Lanzetta R, Parrilli M, Molinaro A, Garozzo D. Reflectron MALDI TOF and MALDI TOF/TOF mass spectrometry reveal novel structural details of native lipooligosaccharides. J Mass Spectrom 2011; 46:1135-1142. [PMID: 22124985 DOI: 10.1002/jms.2000] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lipooligosaccharides (LOS) are powerful Gram-negative glycolipids that evade the immune system and invade host animal and vegetal cells. The structural elucidation of LOS is pivotal to understanding the mechanisms of infection at the molecular level. The amphiphilic nature of LOS has been the main obstacle for structural analysis by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Our approach has resolved this important issue and has permitted us to obtain reflectron MALDI mass spectra of LOS to reveal the fine chemical structure with minimal structural variations. The high-quality MALDI mass spectra show LOS species characteristic of molecular ions and defined fragments due to decay in the ion source. The in-source decay yields B-type ions, which correspond to core oligosaccharide(s), and Y-type ions, which are related to lipid A unit(s). MALDI tandem time-of-flight (TOF/TOF) MS of lipid A allowed for the elucidation of its structure directly from purified intact LOS without the need for any chemical manipulations. These findings constitute a significant advancement in the analysis of such an important biomolecule by MALDI MS.
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Affiliation(s)
- Luisa Sturiale
- CNR Istituto per la Chimica e la Tecnologia dei Polimeri, Via P. Gaifami 18, 95126 Catania, Italy
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