1
|
Kim Y, Kim S, Cho KH, Lee JH, Lee J. Antibiofilm Activities of Cinnamaldehyde Analogs against Uropathogenic Escherichia coli and Staphylococcus aureus. Int J Mol Sci 2022; 23:ijms23137225. [PMID: 35806244 PMCID: PMC9267110 DOI: 10.3390/ijms23137225] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 06/24/2022] [Accepted: 06/26/2022] [Indexed: 02/04/2023] Open
Abstract
Bacterial biofilm formation is a major cause of drug resistance and bacterial persistence; thus, controlling pathogenic biofilms is an important component of strategies targeting infectious bacterial diseases. Cinnamaldehyde (CNMA) has broad-spectrum antimicrobial and antibiofilm activities. In this study, we investigated the antibiofilm effects of ten CNMA derivatives and trans-CNMA against Gram-negative uropathogenic Escherichia coli (UPEC) and Gram-positive Staphylococcus aureus. Among the CNMA analogs tested, 4-nitrocinnamaldehyde (4-nitroCNMA) showed antibacterial and antibiofilm activities against UPEC and S. aureus with minimum inhibitory concentrations (MICs) for cell growth of 100 µg/mL, which were much more active than those of trans-CNMA. 4-NitroCNMA inhibited UPEC swimming motility, and both trans-CNMA and 4-nitroCNMA reduced extracellular polymeric substance production by UPEC. Furthermore, 4-nitroCNMA inhibited the formation of mixed UPEC/S. aureus biofilms. Collectively, our observations indicate that trans-CNMA and 4-nitroCNMA potently inhibit biofilm formation by UPEC and S. aureus. We suggest efforts be made to determine the therapeutic scope of CNMA analogs, as our results suggest CNMA derivatives have potential therapeutic use for biofilm-associated diseases.
Collapse
Affiliation(s)
- Yeseul Kim
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea; (Y.K.); (S.K.)
| | - Sanghun Kim
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea; (Y.K.); (S.K.)
| | - Kiu-Hyung Cho
- Gyeongbuk Institute for Bioindustry, Andong 36618, Korea;
| | - Jin-Hyung Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea; (Y.K.); (S.K.)
- Correspondence: (J.-H.L.); (J.L.); Tel.: +82-53-810-3812 (J.-H.L.); +82-53-810-2533 (J.L.)
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea; (Y.K.); (S.K.)
- Correspondence: (J.-H.L.); (J.L.); Tel.: +82-53-810-3812 (J.-H.L.); +82-53-810-2533 (J.L.)
| |
Collapse
|
2
|
Feng J, Sun D, Wang L, Li X, Guan J, Wei L, Yue D, Wang X, Zhao Y, Yang H, Song W, Wang B. Biochanin A as an α-hemolysin inhibitor for combating methicillin-resistant Staphylococcus aureus infection. World J Microbiol Biotechnol 2021; 38:6. [PMID: 34837116 DOI: 10.1007/s11274-021-03182-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/28/2021] [Indexed: 12/29/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen that poses a significant risk to global health today. In S. aureus, α-hemolysin is an important virulence factor as it contributes to the capacity of the bacteria to infect the host. Here, we showed that biochanin A (bioA), an isoflavone present in red clover, cabbage and alfalfa, effectively inhibited hemolytic activity at a dose as low as 32 μg/mL. Further, western blot and RT-qPCR data showed that bioA reduced the production and expression of MRSA hemolysin in a dose-dependent manner. In addition, when different concentrations of bioA were added to a coculture system of A549 cells and S. aureus, it could significantly decrease cell injury. Importantly, the in vivo study showed that bioA could protect mice from pneumonia caused by a lethal dose of MRSA, as evidenced by improving their survival and reducing the number of bacterial colonies in lung tissues, the secretion of hemolysin into alveolar lavage fluid and the degree of pulmonary edema. In conclusion, biochanin A protected the host from MRSA infection by inhibiting the expression of the hemolysin of MRSA, which may provide experimental evidence for its development to a potential anti-MRSA drug.
Collapse
Affiliation(s)
- Jiaxuan Feng
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Dazhong Sun
- First School of Clinical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, China
| | - Li Wang
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Xueting Li
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Jiyu Guan
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Lin Wei
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Donghui Yue
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Xingye Wang
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Yicheng Zhao
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Haimiao Yang
- Affiliated Hospital to Changchun University of Chinese Medicine, Changchun, 130021, China
| | - Wu Song
- Changchun University of Chinese Medicine, Changchun, 130117, China.
| | - Bingmei Wang
- Changchun University of Chinese Medicine, Changchun, 130117, China.
| |
Collapse
|
3
|
Hille MM, Clawson ML, Dickey AM, Lowery JH, Loy JD. MALDI-TOF MS Biomarker Detection Models to Distinguish RTX Toxin Phenotypes of Moraxella bovoculi Strains Are Enhanced Using Calcium Chloride Supplemented Agar. Front Cell Infect Microbiol 2021; 11:632647. [PMID: 33796479 PMCID: PMC8007961 DOI: 10.3389/fcimb.2021.632647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/01/2021] [Indexed: 11/16/2022] Open
Abstract
Moraxella bovoculi is the bacterium most often cultured from ocular lesions of cattle with infectious bovine keratoconjunctivitis, also known as bovine pinkeye. Some strains of M. bovoculi contain operons encoding for a repeats-in-toxin (RTX) toxin, which is a known virulence factor of multiple veterinary pathogens. We explored the utility of MALDI-TOF MS and biomarker detection models to classify the presence or absence of an RTX phenotype in M. bovoculi. Ninety strains that had undergone whole genome sequencing were classified by the presence or absence of complete RTX operons and confirmed with a visual assessment of hemolysis on blood agar. Strains were grown on Tryptic Soy Agar (TSA) with 5% sheep blood, TSA with 5% bovine blood that was supplemented with 10% fetal bovine serum, 10 mmol/LCaCl2, or both. The formulations were designed to determine the influence of growth media on toxin production or activity, as calcium ions are required for toxin secretion and activity. Mass spectra were obtained for strains grown on each agar formulation and biomarker models were developed using ClinProTools 3.0 software. The most accurate model was developed using spectra from strains grown on TSA with 5% bovine blood and supplemented with CaCl2, which had a sensitivity and specificity of 93.3% and 73.3%, respectively, regarding RTX phenotype classification. The same biomarker model algorithm developed from strains grown on TSA with 5% sheep blood had a substantially lower sensitivity and specificity of 68.0% and 52.0%, respectively. Our results indicate that MALDI-TOF MS biomarker models can accurately classify strains of M. bovoculi regarding the presence or absence of RTX toxin operons and that agar media modifications improve the accuracy of these models.
Collapse
Affiliation(s)
- Matthew M Hille
- School of Veterinary Medicine and Biomedical Sciences, Institute for Agriculture and Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Michael L Clawson
- U.S. Meat Animal Research Center, United States Department of Agriculture, Agricultural Research Service, Clay Center, NE, United States
| | - Aaron M Dickey
- U.S. Meat Animal Research Center, United States Department of Agriculture, Agricultural Research Service, Clay Center, NE, United States
| | - Justin H Lowery
- School of Veterinary Medicine and Biomedical Sciences, Institute for Agriculture and Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - John Dustin Loy
- School of Veterinary Medicine and Biomedical Sciences, Institute for Agriculture and Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, United States
| |
Collapse
|
4
|
Kim YG, Lee JH, Raorane CJ, Oh ST, Park JG, Lee J. Herring Oil and Omega Fatty Acids Inhibit Staphylococcus aureus Biofilm Formation and Virulence. Front Microbiol 2018; 9:1241. [PMID: 29963020 PMCID: PMC6014104 DOI: 10.3389/fmicb.2018.01241] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/23/2018] [Indexed: 11/25/2022] Open
Abstract
Staphylococcus aureus is notorious for its ability to become resistant to antibiotics and biofilms play a critical role in antibiotic tolerance. S. aureus is also capable of secreting several exotoxins associated with the pathogenesis of sepsis and pneumonia. Thus, the objectives of the study were to examine S. aureus biofilm formation in vitro, and the effects of herring oil and its main components, omega fatty acids [cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) and cis-5,8,11,14,17-eicosapentaenoic acid (EPA)], on virulence factor production and transcriptional changes in S. aureus. Herring oil decreased biofilm formation by two S. aureus strains. GC-MS analysis revealed the presence of several polyunsaturated fatty acids in herring oil, and of these, two omega-3 fatty acids, DHA and EPA, significantly inhibited S. aureus biofilm formation. In addition, herring oil, DHA, and EPA at 20 μg/ml significantly decreased the hemolytic effect of S. aureus on human red blood cells, and when pre-treated to S. aureus, the bacterium was more easily killed by human whole blood. Transcriptional analysis showed that herring oil, DHA, and EPA repressed the expression of the α-hemolysin hla gene. Furthermore, in a Caenorhabditis elegans nematode model, all three prolonged nematode survival in the presence of S. aureus. These findings suggest that herring oil, DHA, and EPA are potentially useful for controlling persistent S. aureus infection.
Collapse
Affiliation(s)
- Yong-Guy Kim
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Jin-Hyung Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Chaitany J Raorane
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Seong T Oh
- College of Pharmacy, Yeungnam University, Gyeongsan, South Korea
| | - Jae G Park
- Advanced Bio Convergence Center, Pohang Technopark Foundation, Pohang, South Korea
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| |
Collapse
|
5
|
Kim JS, Song S, Lee M, Lee S, Lee K, Ha NC. Crystal Structure of a Soluble Fragment of the Membrane Fusion Protein HlyD in a Type I Secretion System of Gram-Negative Bacteria. Structure 2016; 24:477-85. [DOI: 10.1016/j.str.2015.12.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 10/22/2022]
|
6
|
Staphylococcal α-hemolysin is neurotoxic and causes lysis of brain cells in vivo and in vitro. Neurotoxicology 2015; 48:61-7. [PMID: 25757835 DOI: 10.1016/j.neuro.2015.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/25/2015] [Accepted: 03/02/2015] [Indexed: 01/11/2023]
Abstract
Formation of a bacterial brain abscess entails loss of brain cells and formation of pus. The mechanisms behind the cell loss are not fully understood. Staphylococcus aureus, a common cause of brain abscesses, produces various exotoxins, including α-hemolysin, which is an important factor in brain abscess formation. α-Hemolysin may cause cytolysis by forming pores in the plasma membrane of various eukaryotic cells. However, whether α-hemolysin causes lysis of brain cells is not known. Nor is it known whether α-hemolysin in the brain causes cell death through pore formation or by acting as a chemoattractant, recruiting leukocytes and causing inflammation. Here we show that α-hemolysin injected into rat brain causes cell damage and edema formation within 30 min. Cell damage was accompanied by an increase in extracellular concentrations of zinc, GABA, glutamate, and other amino acids, indicating plasma membrane damage, but leukocytic infiltration was not seen 0.5-12h after α-hemolysin injection. This was in contrast to injection of S. aureus, which triggered extensive infiltration with neutrophils within 8h. In vitro, α-hemolysin caused concentration-dependent lysis of isolated nerve endings and cultured astrocytes. We conclude that α-hemolysin contributes to the cell death inherent in staphylococcal brain abscess formation as a pore-forming neurotoxin.
Collapse
|
7
|
Oscherwitz J, Cease KB. Identification and validation of a linear protective neutralizing epitope in the β-pore domain of alpha toxin. PLoS One 2015; 10:e0116882. [PMID: 25635901 PMCID: PMC4311967 DOI: 10.1371/journal.pone.0116882] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 12/16/2014] [Indexed: 02/07/2023] Open
Abstract
The plethora of virulence factors associated with Staphylococcus aureus make this bacterium an attractive candidate for a molecularly-designed epitope-focused vaccine. This approach, which necessitates the identification of neutralizing epitopes for incorporation into a vaccine construct, is being evaluated for pathogens where conventional approaches have failed to elicit protective humoral responses, like HIV-1 and malaria, but may also hold promise for pathogens like S. aureus, where the elicitation of humoral immunity against multiple virulence factors may be required for development of an effective vaccine. Among the virulence factors employed by S. aureus, animal model and epidemiological data suggest that alpha toxin, a multimeric β-pore forming toxin like protective antigen from Bacillus anthracis, is particularly critical, yet no candidate neutralizing epitopes have been delineated in alpha toxin to date. We have previously shown that a linear determinant in the 2β2-2β3 loop of the pore forming domain of B. anthracis protective antigen is a linear neutralizing epitope. Antibody against this site is highly potent for neutralizing anthrax lethal toxin in vitro and for protection of rabbits in vivo from virulent B. anthracis. We hypothesized that sequences in the β-pore of S. aureus alpha toxin that share structural and functional homology to β-pore sequences in protective antigen would contain a similarly critical neutralizing epitope. Using an in vivo mapping strategy employing peptide immunogens, an optimized in vitro toxin neutralization assay, and an in vivo dermonecrosis model, we have now confirmed the presence of this epitope in alpha toxin, termed the pore neutralizing determinant. Antibody specific for this determinant neutralizes alpha toxin in vitro, and is highly effective for mitigating dermonecrosis and bacterial growth in a mouse model of S. aureus USA300 skin infection. The delineation of this linear neutralizing determinant in alpha toxin could facilitate the development of an epitope-focused vaccine against S. aureus.
Collapse
Affiliation(s)
- Jon Oscherwitz
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, 48105, United States of America; VA Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, Michigan, 48105, United States of America
| | - Kemp B Cease
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, 48105, United States of America; VA Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, Michigan, 48105, United States of America
| |
Collapse
|
8
|
Nielsen A, Månsson M, Bojer MS, Gram L, Larsen TO, Novick RP, Frees D, Frøkiær H, Ingmer H. Solonamide B inhibits quorum sensing and reduces Staphylococcus aureus mediated killing of human neutrophils. PLoS One 2014; 9:e84992. [PMID: 24416329 PMCID: PMC3885660 DOI: 10.1371/journal.pone.0084992] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 11/22/2013] [Indexed: 11/18/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a serious human pathogen, and particularly the spread of community associated (CA)-MRSA strains such as USA300 is a concern, as these strains can cause severe infections in otherwise healthy adults. Recently, we reported that a cyclodepsipeptide termed Solonamide B isolated from the marine bacterium, Photobacterium halotolerans strongly reduces expression of RNAIII, the effector molecule of the agr quorum sensing system. Here we show that Solonamide B interferes with the binding of S. aureus autoinducing peptides (AIPs) to sensor histidine kinase, AgrC, of the agr two-component system. The hypervirulence of USA300 has been linked to increased expression of central virulence factors like α-hemolysin and the phenol soluble modulins (PSMs). Importantly, in strain USA300 Solonamide B dramatically reduced the activity of α-hemolysin and the transcription of psma encoding PSMs with an 80% reduction in toxicity of supernatants towards human neutrophils and rabbit erythrocytes. To our knowledge this is the first report of a compound produced naturally by a Gram-negative marine bacterium that interferes with agr and affects both RNAIII and AgrA controlled virulence gene expression in S. aureus.
Collapse
Affiliation(s)
- Anita Nielsen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maria Månsson
- Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Martin S. Bojer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lone Gram
- Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Thomas O. Larsen
- Center for Microbial Biotechnology, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Richard P. Novick
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, United States of America
| | - Dorte Frees
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hanne Frøkiær
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| |
Collapse
|
9
|
Lee M, Jun SY, Yoon BY, Song S, Lee K, Ha NC. Membrane fusion proteins of type I secretion system and tripartite efflux pumps share a binding motif for TolC in gram-negative bacteria. PLoS One 2012; 7:e40460. [PMID: 22792337 PMCID: PMC3391258 DOI: 10.1371/journal.pone.0040460] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 06/07/2012] [Indexed: 11/18/2022] Open
Abstract
The Hly translocator complex of Escherichia coli catalyzes type I secretion of the toxin hemolysin A (HlyA). In this complex, HlyB is an inner membrane ABC (ATP Binding Cassette)-type transporter, TolC is an outer membrane channel protein, and HlyD is a periplasmic adaptor anchored in the inner membrane that bridges HlyB to TolC. This tripartite organization is reminiscent of that of drug efflux systems such as AcrA-AcrB-TolC and MacA-MacB-TolC of E. coli. We have previously shown the crucial role of conserved residues located at the hairpin tip region of AcrA and MacA adaptors during assembly of their cognate systems. In this study, we investigated the role of the putative tip region of HlyD using HlyD mutants with single amino acid substitutions at the conserved positions. In vivo and in vitro data show that all mutations abolished HlyD binding to TolC and resulted in the absence of HlyA secretion. Together, our results suggest that, similarly to AcrA and MacA, HlyD interacts with TolC in a tip-to-tip manner. A general model in which these conserved interactions induce opening of TolC during drug efflux and type I secretion is discussed.
Collapse
Affiliation(s)
- Minho Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - So-Young Jun
- Department of Manufacturing Pharmacy, College of Pharmacy, Research Institute for Drug Development, Pusan National University, Busan, Republic of Korea
| | - Bo-Young Yoon
- Department of Manufacturing Pharmacy, College of Pharmacy, Research Institute for Drug Development, Pusan National University, Busan, Republic of Korea
| | - Saemee Song
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Kangseok Lee
- Department of Manufacturing Pharmacy, College of Pharmacy, Research Institute for Drug Development, Pusan National University, Busan, Republic of Korea
- * E-mail: (KL); (NH)
| | - Nam-Chul Ha
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
- * E-mail: (KL); (NH)
| |
Collapse
|
10
|
Adhikari RP, Karauzum H, Sarwar J, Abaandou L, Mahmoudieh M, Boroun AR, Vu H, Nguyen T, Devi VS, Shulenin S, Warfield KL, Aman MJ. Novel structurally designed vaccine for S. aureus α-hemolysin: protection against bacteremia and pneumonia. PLoS One 2012; 7:e38567. [PMID: 22701668 PMCID: PMC3368876 DOI: 10.1371/journal.pone.0038567] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 05/07/2012] [Indexed: 02/05/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is a human pathogen associated with skin and soft tissue infections (SSTI) and life threatening sepsis and pneumonia. Efforts to develop effective vaccines against S. aureus have been largely unsuccessful, in part due to the variety of virulence factors produced by this organism. S. aureus alpha-hemolysin (Hla) is a pore-forming toxin expressed by most S. aureus strains and reported to play a key role in the pathogenesis of SSTI and pneumonia. Here we report a novel recombinant subunit vaccine candidate for Hla, rationally designed based on the heptameric crystal structure. This vaccine candidate, denoted AT-62aa, was tested in pneumonia and bacteremia infection models using S. aureus strain Newman and the pandemic strain USA300 (LAC). Significant protection from lethal bacteremia/sepsis and pneumonia was observed upon vaccination with AT-62aa along with a Glucopyranosyl Lipid Adjuvant-Stable Emulsion (GLA-SE) that is currently in clinical trials. Passive transfer of rabbit immunoglobulin against AT-62aa (AT62-IgG) protected mice against intraperitoneal and intranasal challenge with USA300 and produced significant reduction in bacterial burden in blood, spleen, kidney, and lungs. Our Hla-based vaccine is the first to be reported to reduce bacterial dissemination and to provide protection in a sepsis model of S. aureus infection. AT62-IgG and sera from vaccinated mice effectively neutralized the toxin in vitro and AT62-IgG inhibited the formation of Hla heptamers, suggesting antibody-mediated neutralization as the primary mechanism of action. This remarkable efficacy makes this Hla-based vaccine a prime candidate for inclusion in future multivalent S. aureus vaccine. Furthermore, identification of protective epitopes within AT-62aa could lead to novel immunotherapy for S. aureus infection.
Collapse
Affiliation(s)
- Rajan P. Adhikari
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Hatice Karauzum
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Jawad Sarwar
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Laura Abaandou
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Mahta Mahmoudieh
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Atefeh R. Boroun
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Hong Vu
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Tam Nguyen
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - V. Sathya Devi
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Sergey Shulenin
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Kelly L. Warfield
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - M. Javad Aman
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
- * E-mail:
| |
Collapse
|
11
|
Tubby S, Wilson M, Nair SP. Inactivation of staphylococcal virulence factors using a light-activated antimicrobial agent. BMC Microbiol 2009; 9:211. [PMID: 19804627 PMCID: PMC2762988 DOI: 10.1186/1471-2180-9-211] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 10/05/2009] [Indexed: 12/03/2022] Open
Abstract
Background One of the limitations of antibiotic therapy is that even after successful killing of the infecting microorganism, virulence factors may still be present and cause significant damage to the host. Light-activated antimicrobials show potential for the treatment of topical infections; therefore if these agents can also inactivate microbial virulence factors, this would represent an advantage over conventional antibiotic therapy. Staphylococcus aureus produces a wide range of virulence factors that contribute to its success as a pathogen by facilitating colonisation and destruction of host tissues. Results In this study, the ability of the light-activated antimicrobial agent methylene blue in combination with laser light of 665 nm to inactivate staphylococcal virulence factors was assessed. A number of proteinaceous virulence factors were exposed to laser light in the presence of methylene blue and their biological activities re-determined. The activities of V8 protease, α-haemolysin and sphingomyelinase were shown to be inhibited in a dose-dependent manner by exposure to laser light in the presence of methylene blue. Conclusion These results suggest that photodynamic therapy could reduce the harmful impact of preformed virulence factors on the host.
Collapse
Affiliation(s)
- Sarah Tubby
- Division of Microbial Diseases, UCL Eastman Dental Institute, UK.
| | | | | |
Collapse
|
12
|
Staphylococcal alpha-toxin is not sufficient to mediate escape from phagolysosomes in upper-airway epithelial cells. Infect Immun 2009; 77:3611-25. [PMID: 19564384 DOI: 10.1128/iai.01478-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Intracellular Staphylococcus aureus has been implicated in the establishment of chronic infections. It is therefore imperative to understand by what means S. aureus is able to survive within cells. Here we use two expression systems with a fluorescent readout to assay alpha-toxin expression and function within phagolysosomes of infected upper-airway epithelial cells: avirulent Staphylococcus carnosus TM300 and phenotypically alpha-toxin-negative S. aureus laboratory strains. Data from CFU recovery assays suggest that the presence of alpha-toxin is not beneficial for the intracellular survival of recombinant Staphylococcus strains. This finding was corroborated by immunofluorescence studies: whereas S. carnosus and S. aureus are able to deliver S. aureus alpha-toxin to lumina of host cell phagolysosomes, the membrane integrity of these organelles was not affected. Alpha-toxin-expressing strains were detected exclusively within lysosome-associated membrane protein 1 (LAMP1)-yellow fluorescent protein (YFP)-positive vesicles. Measurements of intraphagosomal pH illustrated that all infected phagolysosomes acidified regardless of alpha-toxin expression. In contrast, S. aureus expressing Listeria monocytogenes listeriolysin O leads to the breakdown of the phagolysosomal membrane, as indicated by staphylococci that are not associated with LAMP1-YFP-decorated vesicles and that do not reside within an acidic cellular environment. Thus, our results suggest that staphylococcal alpha-toxin is not sufficient to mediate phagolysosomal escape in upper-airway epithelial cells.
Collapse
|
13
|
Veldkamp KE, Strijp JAG. Innate Immune Evasion by Staphylococci. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 666:19-31. [DOI: 10.1007/978-1-4419-1601-3_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
14
|
Husmann M, Beckmann E, Boller K, Kloft N, Tenzer S, Bobkiewicz W, Neukirch C, Bayley H, Bhakdi S. Elimination of a bacterial pore-forming toxin by sequential endocytosis and exocytosis. FEBS Lett 2008; 583:337-44. [PMID: 19101547 DOI: 10.1016/j.febslet.2008.12.028] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 12/04/2008] [Accepted: 12/09/2008] [Indexed: 02/02/2023]
Abstract
Staphylococcus aureus alpha-toxin is the archetype of bacterial pore forming toxins and a key virulence factor secreted by the majority of clinical isolates of S. aureus. Toxin monomers bind to target cells and oligomerize to form small beta-barrel pores in the plasma membrane. Many nucleated cells are able to repair a limited number of lesions by unknown, calcium-independent mechanisms. Here we show that cells can internalize alpha-toxin, that uptake is essential for cellular survival, and that pore-complexes are not proteolytically degraded, but returned to the extracellular milieu in the context of exosome-like structures, which we term toxosomes.
Collapse
Affiliation(s)
- Matthias Husmann
- Institute of Medical Microbiology and Hygiene, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Suriyaphol G, Sarikaputi M, Suriyaphol P. Differential responses of cells from human skin keratinocyte and bovine mammary epithelium to attack by pore-forming Staphylococcus aureus alpha-toxin. Comp Immunol Microbiol Infect Dis 2008; 32:491-502. [PMID: 18757097 DOI: 10.1016/j.cimid.2008.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2008] [Indexed: 10/21/2022]
Abstract
Human skin keratinocytes HaCat attacked by Staphylococcus aureus alpha-toxin showed a transient drop of cellular ATP levels whereas in toxin-perforated bovine mammary epithelial cells (BMEC), the ATP levels dropped more slowly. Morphologically, during the ATP level depletion, HaCat cell developed a spacious intracellular vacuole together with the transient influx of trypan blue. WST-1 signal, which tested the function of mitochondrial enzyme in viable cells, also decreased concomitantly. On the other hand, BMEC excluded trypan blue and vacuolation was not observed throughout the experiment. We conclude that mammary epithelial cells resist the toxin better than keratinocytes. This is the first report showing that alpha-toxin enhances transient membrane permeability to large molecules, temporary vacuole formation and the transient defect of mitochondrial enzyme in viable cells without cell lysis.
Collapse
Affiliation(s)
- Gunnaporn Suriyaphol
- Biochemistry Unit, Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
| | | | | |
Collapse
|
16
|
Choi O, Yahiro K, Morinaga N, Miyazaki M, Noda M. Inhibitory effects of various plant polyphenols on the toxicity of Staphylococcal α-toxin. Microb Pathog 2007; 42:215-24. [PMID: 17391908 DOI: 10.1016/j.micpath.2007.01.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2006] [Accepted: 01/29/2007] [Indexed: 11/24/2022]
Abstract
Staphylococcal alpha-toxin, known for its wide spectrum of biological activities, is involved in the pathogenesis of Staphylococcal infectious diseases. In recent years, various phytochemicals have been found to have antimicrobiological, including antibacterial, antiviral and antifungal, and antitoxic activities. We investigated whether several plant polyphenols inhibit alpha-toxin activities in vitro and in vivo. We found hop bract tannin (HBT) and apple condensed tannin (ACT) to exert inhibitory effects on alpha-toxin cytotoxicity. HBT also reduced the murine skin inflammatory effect and the lethality of alpha-toxin. These polyphenols formed aggregates with alpha-toxin and thereby inhibited its activities. Inhibition of alpha-toxin by HBT and ACT was dose dependent, suggesting that these polyphenols may be a useful adjunct to current treatments for alpha-toxin catalyzed Staphylococcal infectious diseases.
Collapse
Affiliation(s)
- Oksun Choi
- Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuo ward, Chiba 260-8670, Japan
| | | | | | | | | |
Collapse
|
17
|
Futagawa-Saito K, Ba-Thein W, Sakurai N, Fukuyasu T. Prevalence of virulence factors in Staphylococcus intermedius isolates from dogs and pigeons. BMC Vet Res 2006; 2:4. [PMID: 16438708 PMCID: PMC1403770 DOI: 10.1186/1746-6148-2-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 01/26/2006] [Indexed: 01/07/2023] Open
Abstract
Background Staphylococcus intermedius has been isolated from healthy dogs and pigeons as well as diseased dogs. Similar to Staphylococcus aureus, S. intermedius is known to carry many virulence factors but most of these factors remain to be studied. In this study, we examined 106 S. intermedius isolates (44 dog isolates and 62 pigeon isolates) for their hemolytic activity, biofilm formation, protease activity, and clumping factor and protein A production. Results Forty-three dog isolates (97.7%) and all pigeon isolates were hemolytic on sheep RBCs with a mean hemolytic titer of 336.7 and 47.32, respectively, whereas 43 dog isolates (97.7%) and 11 pigeon isolates (17.7%) exhibited a significant difference in their hemolytic activity on rabbit RBCs with a mean hemolytic titer of 11.04 and 3.76, respectively (p < 0.0005). The mean biofilm formation activity for dog isolates was 0.49, which was significantly higher than that (0.33) for pigeon isolates (p < 0.0005). Twenty-four dog isolates (54.5%) and 11 pigeon isolates (17.7%) were protease positive. Twenty-four dog isolates (54.5%) were clumping factor- and protein A- positive. Conclusion S. intermedius strains carrying the virulence factors examined in this study were more prevalent in dogs than pigeons.
Collapse
Affiliation(s)
- Keiko Futagawa-Saito
- Department of Animal Health 2, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa, 229-8501, Japan
| | - William Ba-Thein
- Department of Molecular Microbiology/Immunology, Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus, Pathum-thani, 12121, Thailand
| | - Naomi Sakurai
- Center for Medical Sciences, School of Health Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2 Ami, Inashiki, Ibaraki, 300-0394, Japan
| | - Tsuguaki Fukuyasu
- Department of Animal Health 2, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa, 229-8501, Japan
| |
Collapse
|
18
|
|
19
|
Bhakdi S, Tranum-Jensen J. Damage to mammalian cells by proteins that form transmembrane pores. Rev Physiol Biochem Pharmacol 2005; 107:147-223. [PMID: 3303271 DOI: 10.1007/bfb0027646] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
20
|
Hemolysin production by Staphylococcus aureus species isolated from mastitic goat milk in Brazilian dairy herds. Small Rumin Res 2005. [DOI: 10.1016/j.smallrumres.2004.04.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
21
|
Laohachai KN, Bahadi R, Hardo MB, Hardo PG, Kourie JI. The role of bacterial and non-bacterial toxins in the induction of changes in membrane transport: implications for diarrhea. Toxicon 2003; 42:687-707. [PMID: 14757199 DOI: 10.1016/j.toxicon.2003.08.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacterial toxins induce changes in membrane transport which underlie the loss of electrolyte homeostasis associated with diarrhea. Bacterial- and their secreted toxin-types which have been linked with diarrhea include: (a) Vibrio cholerae (cholera toxin, E1 Tor hemolysin and accessory cholera enterotoxin); (b) Escherichia coli (heat stable enterotoxin, heat-labile enterotoxin and colicins); (c) Shigella dysenteriae (shiga-toxin); (d) Clostridium perfringens (C. perfringens enterotoxin, alpha-toxin, beta-toxin and theta-toxin); (e) Clostridium difficile (toxins A and B); (f) Staphylococcus aureus (alpha-haemolysin); (g) Bacillus cereus (cytotoxin K and haemolysin BL); and (h) Aeromonas hydrophila (aerolysin, heat labile cytotoxins and heat stable cytotoxins). The mechanisms of toxin-induced diarrhea include: (a) direct effects on ion transport in intestinal epithelial cells, i.e. direct toxin interaction with intrinsic ion channels in the membrane and (b) indirect interaction with ion transport in intestinal epithelial cells mediated by toxin binding to a membrane receptor. These effects consequently cause the release of second messengers, e.g. the release of adenosine 3',5'-cyclic monophosphate/guanosine 3',5'-monophosphate, IP(3), Ca2+ and/or changes in second messengers that are the result of toxin-formed Ca2+ and K+ permeable channels, which increase Ca2+ flux and augment changes in Ca2+ homeostasis and cause depolarisation of the membrane potential. Consequently, many voltage-dependent ion transport systems, e.g. voltage-dependent Ca2+ influx, are affected. The toxin-formed ion channels may act as a pathway for loss of fluid and electrolytes. Although most of the diarrhea-causing toxins have been reported to act via cation and anion channel formation, the properties of these channels have not been well studied, and the available biophysical properties that are needed for the characterization of these channels are inadequate.
Collapse
Affiliation(s)
- Karina N Laohachai
- Membrane Transport Group, Department of Chemistry, Building 33, The Faculty of Science, The Australian National University, Canberra, ACT 0200, Australia
| | | | | | | | | |
Collapse
|
22
|
Valeva A, Schnabel R, Walev I, Boukhallouk F, Bhakdi S, Palmer M. Membrane insertion of the heptameric staphylococcal alpha-toxin pore. A domino-like structural transition that is allosterically modulated by the target cell membrane. J Biol Chem 2001; 276:14835-41. [PMID: 11279048 DOI: 10.1074/jbc.m100301200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Staphylococcal alpha-toxin forms heptameric pores on eukaryotic cells. After binding to the cell membrane in its monomeric form, the toxin first assembles into a heptameric pre-pore. Subsequently, the pre-pore transforms into the final pore by membrane insertion of an amphipathic beta-barrel, which comprises the "central loop" domains of all heptamer subunits. The process of membrane insertion was analyzed here using a set of functionally altered toxin mutants. The results show that insertion may be initiated within an individual protomer when its NH2 terminus activates its central loop. The activated state is then shared with the central loops of the residual heptamer subunits, which results in cooperative membrane penetration. This cooperation of the central loops commences while these are still remote from the lipid bilayer. Nevertheless, it is subject to modulation by the target membrane, which therefore acts across a distance much like an allosteric effector. However, while allosteric transitions usually are reversible, membrane insertion of alpha-toxin is an irreversible event, and we show here that it can proceed to completion in a domino-like fashion when triggered by as little as a single foreign atom within the entire heptamer.
Collapse
Affiliation(s)
- A Valeva
- Institute of Medical Microbiology and Hygiene, University of Mainz, Obere Zahlbacher Strasse 67, D55101 Mainz, Germany.
| | | | | | | | | | | |
Collapse
|
23
|
Edwards L, Hessinger DA. Portuguese Man-of-war (Physalia physalis) venom induces calcium influx into cells by permeabilizing plasma membranes. Toxicon 2000; 38:1015-28. [PMID: 10708794 DOI: 10.1016/s0041-0101(99)00213-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Portuguese Man-of-war (Physalia physalis) nematocyst venom dose-dependently stimulates calcium (45Ca(2+)) influx into L-929, GH(4)C(1), FRL, and embryonic chick heart cells. Venom-induced calcium influx is not blocked by ouabain, vanadate, nor organic calcium channel blockers, but is blocked by transition metal cations, such as lanthanum and zinc. Venom-induced calcium influx is accompanied in a dose-dependent manner by the release of intracellular lactate dehydrogenase, indicating a loss in plasma membrane integrity and cytolysis. Concentrations of zinc that block 45Ca(2+) influx also block lactate dehydrogenase release. Lanthanum, which also blocks 45Ca(2+) uptake, does not neutralize the cytolytic activity of the venom, but rather inhibits the venom's cytolytic action at the level of the target cell plasma membrane. Our findings indicate that Man-of-war venom causes an influx of calcium into several different cells types, not just those of the cardiovascular system, and this influx likely occurs by permeabilizing the plasma membranes of cells.
Collapse
Affiliation(s)
- L Edwards
- Department of Physiology and Pharmacology,School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | | |
Collapse
|
24
|
Abstract
This article reviews the literature regarding the structure and function of two types of exotoxins expressed by Staphylococcus aureus, pyrogenic toxin superantigens (PTSAgs) and hemolysins. The molecular basis of PTSAg toxicity is presented in the context of two diseases known to be caused by these exotoxins: toxic shock syndrome and staphylococcal food poisoning. The family of staphylococcal PTSAgs presently includes toxic shock syndrome toxin-1 (TSST-1) and most of the staphylococcal enterotoxins (SEs) (SEA, SEB, SEC, SED, SEE, SEG, and SEH). As the name implies, the PTSAgs are multifunctional proteins that invariably exhibit lethal activity, pyrogenicity, superantigenicity, and the capacity to induce lethal hypersensitivity to endotoxin. Other properties exhibited by one or more staphylococcal PTSAgs include emetic activity (SEs) and penetration across mucosal barriers (TSST-1). A detailed review of the molecular mechanisms underlying the toxicity of the staphylococcal hemolysins is also presented.
Collapse
|
25
|
Dinges MM, Orwin PM, Schlievert PM. Exotoxins of Staphylococcus aureus. Clin Microbiol Rev 2000; 13:16-34, table of contents. [PMID: 10627489 PMCID: PMC88931 DOI: 10.1128/cmr.13.1.16] [Citation(s) in RCA: 743] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This article reviews the literature regarding the structure and function of two types of exotoxins expressed by Staphylococcus aureus, pyrogenic toxin superantigens (PTSAgs) and hemolysins. The molecular basis of PTSAg toxicity is presented in the context of two diseases known to be caused by these exotoxins: toxic shock syndrome and staphylococcal food poisoning. The family of staphylococcal PTSAgs presently includes toxic shock syndrome toxin-1 (TSST-1) and most of the staphylococcal enterotoxins (SEs) (SEA, SEB, SEC, SED, SEE, SEG, and SEH). As the name implies, the PTSAgs are multifunctional proteins that invariably exhibit lethal activity, pyrogenicity, superantigenicity, and the capacity to induce lethal hypersensitivity to endotoxin. Other properties exhibited by one or more staphylococcal PTSAgs include emetic activity (SEs) and penetration across mucosal barriers (TSST-1). A detailed review of the molecular mechanisms underlying the toxicity of the staphylococcal hemolysins is also presented.
Collapse
Affiliation(s)
- M M Dinges
- Department of Microbiology, University of Minnesota School of Medicine, Minneapolis, Minnesota 55455, USA
| | | | | |
Collapse
|
26
|
Merzlyak PG, Yuldasheva LN, Rodrigues CG, Carneiro CM, Krasilnikov OV, Bezrukov SM. Polymeric nonelectrolytes to probe pore geometry: application to the alpha-toxin transmembrane channel. Biophys J 1999; 77:3023-33. [PMID: 10585924 PMCID: PMC1300573 DOI: 10.1016/s0006-3495(99)77133-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Asymmetrical (one-sided) application of penetrating water-soluble polymers, polyethylene glycols (PEGs), to a well-defined channel formed by Staphylococcus aureus alpha-toxin is shown to probe channel pore geometry in more detail than their symmetrical (two-sided) application. Polymers added to the cis side of the planar lipid membrane (the side of protein addition) affect channel conductance differently than polymers added to the trans side. Because a satisfactory theory quantitatively describing PEG partitioning into a channel pore does not exist, we apply the simple empirical rules proposed previously (, J. Membr. Biol. 161:83-92) to gauge the size of pore openings as well as the size and position of constrictions along the pore axis. We estimate the radii of the two openings of the channel to be practically identical and equal to 1. 2-1.3 nm. Two apparent constrictions with radii of approximately 0. 9 nm and approximately 0.6-0.7 nm are inferred to be present in the channel lumen, the larger one being closer to the cis side. These structural findings agree well with crystallographic data on the channel structure (, Science. 274:1859-1866) and verify the practicality of polymer probing. The general features of PEG partitioning are examined using available theoretical considerations, assuming there is no attraction between PEG and the channel lumen. It is shown that the sharp dependence of the partition coefficient on polymer molecular weight found under both symmetrical and asymmetrical polymer application can be rationalized within a "hard sphere nonideal solution model." This finding is rather surprising because PEG forms highly flexible coils in water with a Kuhn length of only several Angstroms.
Collapse
Affiliation(s)
- P G Merzlyak
- Laboratory of Membrane Biophysics, Department of Biophysics and Radiobiology, Federal University of Pernambuco, 50670-901, Recife, PE, Brazil
| | | | | | | | | | | |
Collapse
|
27
|
Cheley S, Braha O, Lu X, Conlan S, Bayley H. A functional protein pore with a "retro" transmembrane domain. Protein Sci 1999; 8:1257-67. [PMID: 10386875 PMCID: PMC2144353 DOI: 10.1110/ps.8.6.1257] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Extended retro (reversed) peptide sequences have not previously been accommodated within functional proteins. Here, we show that the entire transmembrane portion of the beta-barrel of the pore-forming protein alpha-hemolysin can be formed by retrosequences comprising a total of 175 amino acid residues, 25 contributed by the central sequence of each subunit of the heptameric pore. The properties of wild-type and retro heptamers in planar bilayers are similar. The single-channel conductance of the retro pore is 15% less than that of the wild-type heptamer and its current-voltage relationship denotes close to ohmic behavior, while the wild-type pore is weakly rectifying. Both wild-type and retro pores are very weakly anion selective. These results and the examination of molecular models suggest that beta-barrels may be especially accepting of retro sequences compared to other protein folds. Indeed, the ability to form a retro domain could be diagnostic of a beta-barrel, explaining, for example, the activity of the retro forms of many membrane-permeabilizing peptides. By contrast with the wild-type subunits, monomeric retro subunits undergo premature assembly in the absence of membranes, most likely because the altered central sequence fails to interact with the remainder of the subunit, thereby initiating assembly. Despite this difficulty, a technique was devised for obtaining heteromeric pores containing both wild-type and retro subunits. Most probably as a consequence of unfavorable interstrand side-chain interactions, the heteromeric pores are less stable than either the wild-type or retro homoheptamers, as judged by the presence of subconductance states in single-channel recordings. Knowledge about the extraordinary plasticity of the transmembrane beta-barrel of alpha-hemolysin will be very useful in the de novo design of functional membrane proteins based on the beta-barrel motif.
Collapse
Affiliation(s)
- S Cheley
- Department of Medical Biochemistry and Genetics, Texas A&M Health Science Center, College Station 77843-1114, USA
| | | | | | | | | |
Collapse
|
28
|
Swärd K, Dreja K, Hellstrand P. Contractile effects of polycations in permeabilized smooth muscle. J Muscle Res Cell Motil 1998; 19:463-72. [PMID: 9682133 DOI: 10.1023/a:1005368728376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The polycations spermine, neomycin and polylysine potentiated Ca(2+)-activated force in beta-escin permeabilized guinea-pig ileum strips. The effect was inhibited by the calmodulin antagonists trifluoperazine, mastoparan and W13. Potentiation was slow or absent in chi-toxin permeabilized strips, indicating dependence on penetration of the polycations into cells. The effects of spermine and neomycin were maintained after extensive permeabilization by beta-escin, which eliminated the contractile effect of GTPgammaS. Replacement of ATP by CTP, which is not a substrate for myosin light chain kinase, inhibited contractile potentiation. Potentiation of Ca(2+)-activated contractions was associated with increased phosphorylation of the myosin regulatory light chains (LC20). A contractile effect of polylysine and neomycin was also seen in Ca(2+)-free medium and after partial LC20 thiophosphorylation, indicating that phosphorylation-independent processes may contribute to the response. Although spermine does not cause contraction in Ca(2+)-free medium at physiological [MgATP], it did so when [MgATP] was lowered to 40 micron. Similar to high-[Mg2+], the rate of contraction on addition of ATP to strips incubated with microcystin-LR in inhibit phosphatase activity was increased by the polycations, but only at [Ca2+] < 0.3 micron. The results suggest that polycations increase Ca(2+)-activated force by inhibiting myosin phosphatase activity, thereby increasing myosin LC20 phosphorylation. However, additional activation mechanisms, evident at low [Ca2+] and at low [ATP] and possibly involving direct activation of myosin, contribute to their effect.
Collapse
Affiliation(s)
- K Swärd
- Department of Physiology and Neuroscience, Lund University, Sweden
| | | | | |
Collapse
|
29
|
Korchev YE, Bashford CL, Pederzolli C, Pasternak CA, Morgan PJ, Andrew PW, Mitchell TJ. A conserved tryptophan in pneumolysin is a determinant of the characteristics of channels formed by pneumolysin in cells and planar lipid bilayers. Biochem J 1998; 329 ( Pt 3):571-7. [PMID: 9445384 PMCID: PMC1219078 DOI: 10.1042/bj3290571] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Pneumolysin is one of the family of thiol-activatable, cytolytic toxins. Within these toxins the amino acid sequence Trp-Glu-Trp-Trp is conserved. Mutations made in this region of pneumolysin, residues 433-436 inclusive, did not affect cell binding or the formation of toxin oligomers in the target cell membrane. However, the mutations did affect haemolysis, leakage of low-molecular-mass metabolites from Lettre cells and the induction of conductance channels across planar lipid bilayers. Of eight modified pneumolysins examined, Trp-433-->Phe showed the smallest amount of haemolysis or leakage (less than 5% of wild type). Pneumolysin-induced leakage from Lettre cells was sensitive to inhibition by bivalent cations but the extent of inhibition varied depending on the modification. Leakage by the mutant Trp-433-->Phe was least sensitive to cation inhibition. The ion-conducting channels formed across planar lipid bilayers exhibit small (less than 30 pS), medium (30 pS-1 nS) and large (more than 1 nS) conductance steps. Small- and medium-sized channels were preferentially closed by bivalent cations. In contrast with wild-type toxin, which formed predominantly small channels, the modified toxin Trp-433-->Phe formed large channels that were insensitive to cation-induced closure. Polysaccharides of molecular mass more than 15 kDa inhibited haemolysis by wild-type toxin, but polysaccharide of up to 40 kDa did not prevent haemolysis by Trp-433-->Phe. Electron microscopy revealed that Trp-433-->Phe formed oligomeric arc and ring structures with dimensions identical with those of wild-type toxin, and that the ratio of arcs to rings formed was the same for wild-type toxin and the Trp-433-->Phe variant. We conclude that the change Trp-433-->Phe affects channel formation at a point subsequent to binding to the cell membrane and the formation of oligomers, and that the size of arc and ring structures revealed by electron microscopy does not reflect the functional state of the channels.
Collapse
Affiliation(s)
- Y E Korchev
- Department of Cellular and Molecular Sciences, St. George's Hospital Medical School, London, U.K
| | | | | | | | | | | | | |
Collapse
|
30
|
Ferguson MR, Xu XJ, Houston CW, Peterson JW, Coppenhaver DH, Popov VL, Chopra AK. Hyperproduction, purification, and mechanism of action of the cytotoxic enterotoxin produced by Aeromonas hydrophila. Infect Immun 1997; 65:4299-308. [PMID: 9317040 PMCID: PMC175616 DOI: 10.1128/iai.65.10.4299-4308.1997] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A gene encoding the cytotoxic enterotoxin (Act) from Aeromonas hydrophila was hyperexpressed with the pET, pTRX, and pGEX vector systems. Maximum toxin yield was obtained with the pTRX vector. Approximately 40 to 60% of Act was in a soluble form with the pTRX and pET vector systems. The toxin protein was purified to homogeneity by a combination of ammonium sulfate precipitation and fast protein liquid chromatography-based column chromatographies, including hydrophobic, anion-exchange, sizing, and hydroxylapatite chromatographies. Purified mature toxin migrated as a 52-kDa polypeptide on a sodium dodecyl sulfate (SDS)polyacrylamide gel that reacted with Act-specific antibodies in immunoblots. The minimal amount of toxin needed to cause fluid secretion in rat ileal loops was 200 ng, and the 50% lethal dose for mice was 27.5 ng when injected intravenously. Binding of the toxin to erythrocytes was temperature dependent, with no binding occurring at 4 degrees C. However, at 37 degrees C the toxin bound to erythrocytes within 1 to 2 min. It was determined that the mechanism of action of the toxin involved the formation of pores in erythrocyte membranes, and the diameter of the pores was estimated to be 1.14 to 2.8 nm, as determined by the use of saccharides of different sizes and by electron microscopy. Calcium chloride prevented lysis of erythrocytes by the toxin; however, it did not affect the binding and pore-forming capabilities of the toxin. A dose-dependent reduction in hemoglobin release from erythrocytes was observed when Act was preincubated with cholesterol, but not with myristylated cholesterol. With 14C-labeled cholesterol and gel filtration, the binding of cholesterol to Act was demonstrated. None of the other phospholipids and glycolipids tested reduced the hemolytic activity of Act. The toxin also appeared to undergo aggregation when preincubated with cholesterol, as determined by SDS-polyacrylamide gel electorphoresis. As a result of this aggregation, Act's capacity to form pores in the erythrocyte membrane was inhibited.
Collapse
Affiliation(s)
- M R Ferguson
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston 77555-1070, USA
| | | | | | | | | | | | | |
Collapse
|
31
|
Baida GE, Kuzmin NP. Mechanism of action of hemolysin III from Bacillus cereus. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1284:122-4. [PMID: 8962879 DOI: 10.1016/s0005-2736(96)00168-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Bacillus cereus hemolysin III activity was tested in crude extracts, from Escherichia coli carrying the hly-III gene. It was concluded that hemolysin III is a pore-forming hemolysin with functional pore diameter of about 3-3.5 nm. Hemolysis occurs in at least three steps: (i) the temperature-dependent binding of the Hly-III monomers to the erythrocyte membrane; (ii) the temperature-dependent formation of the transmembrane oligomeric pore; (iii) the temperature-independent erythrocyte lysis.
Collapse
Affiliation(s)
- G E Baida
- Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
| | | |
Collapse
|
32
|
Nichol JA, Hutter OF. Ca2+ loading reduces the tensile strength of sarcolemmal vesicles shed from rabbit muscle. J Physiol 1996; 493 ( Pt 1):199-209. [PMID: 8735705 PMCID: PMC1158961 DOI: 10.1113/jphysiol.1996.sp021375] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. Sarcolemmal vesicles shed by rabbit muscle were loaded with Ca2+ by means of A23187 or ionomycin. [Ca2+]0 was buffered between 0.8 and 20 microM. Membrane strength was measured by pipette aspiration. 2. At 20 microM Ca2+ many vesicles underwent autolysis, or were so weak that they burst instantly on aspiration. Between 10 and 2 microM Ca2+ a graded decrease in membrane strength was demonstrable. At 0.8 microM Ca2+ the mechanical properties of the sarcolemma remained unaltered. 3. Mg2+ carried by A23187 does not mimic the effect of Ca2+. The ionophore itself similarly did not cause a decrease in membrane tensile strength. 4. Pre-treatment with BAPTA-AM, so as to buffer internal Ca2+, partly protected vesicles against the decrease in membrane strength produced by Ca2+ loading. 5. Membrane strength was not restored by adding excess BAPTA to the bathing solution, so as to reverse the Ca2+ gradient. An irreversible degradation of the membrane consequent upon raised [Ca2+]1 seems indicated. 6. These findings are discussed in relation to the mechanisms which have been advanced to account for the role of elevated [Ca2+]1 in cell death. 7. An attempt to use staphylococcal alpha-toxin as an alternative means to permeabilize the sarcolemma led to the incidental finding that this pore-forming protein itself greatly weakens the membrane in doses lower than required for effective permeabilization.
Collapse
Affiliation(s)
- J A Nichol
- Institute of Physiology, University of Glasgow, UK
| | | |
Collapse
|
33
|
Valeva A, Weisser A, Walker B, Kehoe M, Bayley H, Bhakdi S, Palmer M. Molecular architecture of a toxin pore: a 15-residue sequence lines the transmembrane channel of staphylococcal alpha-toxin. EMBO J 1996; 15:1857-64. [PMID: 8617232 PMCID: PMC450103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Staphylococcus aureus alpha-toxin is a hydrophilic polypeptide of 293 amino acids that produces heptameric transmembrane pores. During assembly, the formation of a pre-pore precedes membrane permeabilization; the latter is linked to a conformational change in the oligomer. Here, 41 single-cysteine replacement toxin mutants were thiol-specifically labelled with the polarity-sensitive fluorescent probe acrylodan. After oligomerization on membranes, only the mutants with acrylodan attached to residues in the sequence 118-140 exhibited a marked blue shift in the fluorescence emission maximum, indicative of movement of the fluorophore to a hydrophobic environment. Within this region, two functionally distinct parts could be identified. For mutants at positions 126-140, the shifts were partially reversed after membrane solubilization by detergents, indicating a direct interaction of the label with the membrane lipids. Membrane insertion of this sequence occurred together with the final pre-pore to pore transition of the heptamer. Thus residues 126-140 constitute a transmembrane sequence in the pore. With labelled residues 118-124, pre-pore assembly was the critical event to induce the spectral shifts, which persisted after the removal of membrane lipids and hence probably reflects protomer-protomer contacts within the heptamer. Finally, a derivative of the mutant N121C yielded occluded pores which could be opened by reductive reversal of the modification. Therefore this residue probably lines the lumen of the pore.
Collapse
Affiliation(s)
- A Valeva
- Institute of Medical Microbiology and Hygiene, University of Mainz, Germany
| | | | | | | | | | | | | |
Collapse
|
34
|
Bhakdi S, Walev I, Jonas D, Palmer M, Weller U, Suttorp N, Grimminger F, Seeger W. Pathogenesis of sepsis syndrome: possible relevance of pore-forming bacterial toxins. Curr Top Microbiol Immunol 1996; 216:101-18. [PMID: 8791737 DOI: 10.1007/978-3-642-80186-0_5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- S Bhakdi
- Institute of Medical Microbiology and Hygiene, University of Mainz, Germany
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Korchev YE, Bashford CL, Alder GM, Kasianowicz JJ, Pasternak CA. Low conductance states of a single ion channel are not 'closed'. J Membr Biol 1995; 147:233-9. [PMID: 8558589 DOI: 10.1007/bf00234521] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have used a polymer-exclusion method to estimate the sizes of the high- and low-conductance states of Staphylococcus aureus alpha-toxin channels across planar lipid bilayers. Despite a > 10-fold difference in conductance between high- and low-conductance states, the size differs by < 2-fold. We conclude that factors other than the dimensions have a strong influence on the conductance of alpha-toxin channels. We also show that the high conductance state is destabilized by the presence of high molecular weight polymers outside the channel, compatible with the removal of channel water as the high conductance state "shrinks" to the low conductance state.
Collapse
Affiliation(s)
- Y E Korchev
- Department of Cellular & Molecular Sciences, St George's Hospital Medical School, London, UK
| | | | | | | | | |
Collapse
|
36
|
Kasianowicz JJ, Bezrukov SM. Protonation dynamics of the alpha-toxin ion channel from spectral analysis of pH-dependent current fluctuations. Biophys J 1995; 69:94-105. [PMID: 7545444 PMCID: PMC1236228 DOI: 10.1016/s0006-3495(95)79879-4] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
To probe protonation dynamics inside the fully open alpha-toxin ion channel, we measured the pH-dependent fluctuations in its current. In the presence of 1 M NaCl dissolved in H2O and positive applied potentials (from the side of protein addition), the low frequency noise exhibited a single well defined peak between pH 4.5 and 7.5. A simple model in which the current is assumed to change by equal amounts upon the reversible protonation of each of N identical ionizable residues inside the channel describes the data well. These results, and the frequency dependence of the spectral density at higher frequencies, allow us to evaluate the effective pK = 5.5, as well as the rate constants for the reversible protonation reactions: kon = 8 x 10(9) M-1 s-1 and koff = 2.5 x 10(4) s-1. The estimate of kon is only slightly less than the diffusion-limited values measured by others for protonation reactions for free carboxyl or imidazole residues. Substitution of H2O by D2O caused a 3.8-fold decrease in the dissociation rate constant and shifted the pK to 6.0. The decrease in the ionization rate constants caused by H2O/D2O substitution permitted the reliable measurement of the characteristic relaxation time over a wide range of D+ concentrations and voltages. The dependence of the relaxation time on D+ concentration strongly supports the first order reaction model. The voltage dependence of the low frequency spectral density suggests that the protonation dynamics are virtually insensitive to the applied potential while the rate-limiting barriers for NaCl transport are voltage dependent. The number of ionizable residues deduced from experiments in H2O (N = 4.2) and D2O (N = 4.1) is in good agreement.
Collapse
Affiliation(s)
- J J Kasianowicz
- National Institute of Standards and Technology, Biotechnology Division, Gaithersburg, Maryland 20899, USA
| | | |
Collapse
|
37
|
Valeva A, Palmer M, Hilgert K, Kehoe M, Bhakdi S. Correct oligomerization is a prerequisite for insertion of the central molecular domain of staphylococcal alpha-toxin into the lipid bilayer. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1236:213-8. [PMID: 7794960 DOI: 10.1016/0005-2736(95)00060-g] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Staphylococcal alpha-toxin is a primarily hydrophilic molecule that binds as a monomer to target membranes and then aggregates to form amphiphilic oligomers that represent water-filled transmembrane channels. Current evidence indicates that a region located in the center of the molecule inserts deeply into the bilayer. In the present study, we sought to determine whether membrane insertion was triggered by the oligomerization process, and whether insertion correlated with pore formation. Double mutants of alpha-toxin were prepared in which His-35 was replaced by Arg, and cysteine residues were introduced at positions 69, 130 and 186. Substitution of His-35 with Arg rendered the toxin molecules incapable of proper oligomerization, so that they remained in nonlytic form after binding to membranes. The sulfhydryl groups were labelled with the polarity-sensitive fluorescent dye acrylodan. Functionally intact, single mutant toxins containing only the cysteine residues were utilized as controls. Measurements of the fluorescence emission spectrum of acrylodan were performed for the active and inactive alpha-toxin mutants in free solution and in membrane-bound form. The collective results demonstrate that proper oligomerization is required for membrane insertion of the central region in the alpha-toxin molecule, and that lack of insertion correlates with absence of pore formation.
Collapse
Affiliation(s)
- A Valeva
- Institute of Medical Microbiology and Hygiene, University of Main, Germany
| | | | | | | | | |
Collapse
|
38
|
Walker B, Braha O, Cheley S, Bayley H. An intermediate in the assembly of a pore-forming protein trapped with a genetically-engineered switch. CHEMISTRY & BIOLOGY 1995; 2:99-105. [PMID: 9383410 DOI: 10.1016/1074-5521(95)90282-1] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Studies of the mechanisms by which certain water-soluble proteins can assemble into lipid bilayers are relevant to several areas of biology, including the biosynthesis of membrane and secreted proteins, virus membrane fusion and the action of immune proteins such as complement and perforin. The alpha-hemolysin (alpha HL) protein, an exotoxin secreted by Staphylococcus aureus that forms heptameric pores in lipid bilayers, is a useful model for studying membrane protein assembly. In addition, modified alpha HL might be useful as a component of biosensors or in drug delivery. We have therefore used protein engineering to produce variants of alpha HL that contain molecular triggers and switches with which pore-forming activity can be modulated at will. Previously, we showed that the conductance of pores formed by the mutant hemolysin alpha HL-H5, which contains a Zn(II)-binding pentahistidine sequence, is blocked by Zn(II) from either side of the lipid bilayer, suggesting that residues from the pentahistidine sequence line the lumen of the transmembrane channel. RESULTS Here we show that Zn(II) can arrest the assembly of alpha HL-H5 before pore formation by preventing an impermeable oligomeric prepore from proceeding to the fully assembled state. The prepore is a heptamer. Limited proteolysis shows that, unlike the functional pore, the prepore contains sites near the amino terminus of the polypeptide chain that are exposed to the aqueous phase. Upon removal of the bound Zn(II) with EDTA, pore formation is completed and the sites near the amino terminus become occluded. Conversion of the prepore to the active pore is the rate-determining step in assembly and cannot be reversed by the subsequent addition of excess Zn(II). CONCLUSIONS The introduction of a simple Zn(II)-binding motif into a pore-forming protein has allowed the isolation of a defined intermediate in assembly. Genetically-engineered switches for trapping and releasing intermediates that are actuated by metal coordination or other chemistries might be generally useful for analyzing the assembly of membrane proteins and other supramolecular structures.
Collapse
Affiliation(s)
- B Walker
- Worcester Foundation for Experimental Biology, Shrewsbury, MA 01545-2737, USA
| | | | | | | |
Collapse
|
39
|
Walev I, Martin E, Jonas D, Mohamadzadeh M, Müller-Klieser W, Kunz L, Bhakdi S. Staphylococcal alpha-toxin kills human keratinocytes by permeabilizing the plasma membrane for monovalent ions. Infect Immun 1993; 61:4972-9. [PMID: 8225571 PMCID: PMC281271 DOI: 10.1128/iai.61.12.4972-4979.1993] [Citation(s) in RCA: 141] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Incubation of human keratinocytes with nanomolar concentrations of Staphylococcus aureus alpha-toxin leads to irreversible depletion of cellular ATP. The toxin forms hexamers in the target cell membranes, and rapid transmembrane flux of K+, Na+, and 86Rb+ is observed. Unexpectedly, pores formed in keratinocytes through application of low but lethal doses of alpha-toxin appeared to be considerably smaller than those formed in erythrocyte membranes. They permitted neither rapid influx of Ca2+ or propidium iodide, nor efflux of carboxyfluorescein. Larger pores allowing flux of all three markers did form when the toxin was applied at high concentrations. Flux of monovalent ions and reduction in cellular ATP levels evoked by low toxin doses correlated temporally with a fall in oxygen consumption, which was interpreted to reflect breakdown of mitochondrial respiration. The lethal event could not be thwarted by manipulating the extracellular K+ or Ca2+ concentrations. Realization that alpha-toxin may form very small pores in nucleated cells is important for future research on cellular toxin effects and membrane repair processes.
Collapse
Affiliation(s)
- I Walev
- Institute of Medical Microbiology, University of Mainz, Germany
| | | | | | | | | | | | | |
Collapse
|
40
|
Zitzer AO, Nakisbekov NO, Li AV, Semiotrochev VL, Muratkhodjaev JN, Krasilnikov OV. Entero-cytolysin (EC) from Vibrio cholerae non-O1 (some properties and pore-forming activity). ZENTRALBLATT FUR BAKTERIOLOGIE : INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 1993; 279:494-504. [PMID: 7508299 DOI: 10.1016/s0934-8840(11)80421-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A thermolabile extracellular entero-cytolysin (EC) from Vibrio cholerae non-O1 was purified by ammonium sulphate fractionation, DE-52 cellulose ion exchange chromatography, gel-filtration on Ultrogel AcA-44 and high performance liquid chromatography on a Mono Q. The purified EC had a molecular weight of 63 kD and an isoelectric point of 6.2. It was not inactivated by cholesterol or 5,5'-dithio-bis(2-nitrobenzoic acid), nor activated by dithiothreitol. EC had no immunological cross-reactivity with cholera toxin. The EC caused fluid accumulation in the intestines of infant rabbits, death of mice by intravenous injection, and increased vascular permeability in the paw oedema test in mice. V. cholerae non-O1 EC lysed erythrocytes from various species and cultured cells (CHO, L-929, L-41, HEp-2, Vero, MDCK and BHK-21). In contrast to cholera toxin, EC caused crude destruction of target cells. The EC caused hemolysis by a colloid-osmotic mechanism due to the formation of hydrophilic pores of 1.8-2.0 nm diameter in the cell membrane. This EC also was able to open pores in lipid membranes. The induced channels were anion-selective and had a diameter of 1.8-2.0 nm.
Collapse
Affiliation(s)
- A O Zitzer
- Middle Asian Antiplague Research Institute, Alma-Ata, Kazakhstan
| | | | | | | | | | | |
Collapse
|
41
|
Cauci S, Monte R, Ropele M, Missero C, Not T, Quadrifoglio F, Menestrina G. Pore-forming and haemolytic properties of the Gardnerella vaginalis cytolysin. Mol Microbiol 1993; 9:1143-55. [PMID: 7934928 DOI: 10.1111/j.1365-2958.1993.tb01244.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The pleomorphic bacterium Gardnerella vaginalis releases in the culture broth a haemolytic exotoxin (Gvh) which is probably a virulence determinant of this unique bacterium, implicated in gynaecological and urological disorders. This 59 kDa cytolysin was purified to homogeneity in just one chromatographic step directly from the culture supernatant, a final specific activity up to 1.9 x 10(6) HU mg-1 being obtained. The toxin-induced lesion on human erythrocytes results from the formation of a pore whose radius is approximately 2.4 nm. The damage is inhibited by osmotic protectants and shows a sigmoidal dose-response profile suggesting an aggregation process of haemolysin molecules on the target membrane to create the functional lesion. The extent and the kinetics of haemolysis are strongly dependent on temperature and an activation energy of 64.0 kJ mol-1 has been derived. Lipid membranes can be very efficient inhibitors of Gvh-haemolysis, being able to bind the toxin quite avidly. The inhibitory effect requires the presence of cholesterol and it is stronger when cholesterol is mixed with negatively charged phospholipids rather than with zwitterionic phospholipids, suggesting that a negative surface potential increases the affinity of the toxin for the lipid bilayer. The functional properties of Gvh have been compared with those of Clostridium perfringens thetatoxin (PFO) and Escherichia coli haemolysin (HlyA), which are representative of widespread haemolysins produced by Gram-positive and Gram-negative bacteria, respectively. The toxin shares several features with the family of the so-called 'sulphydryl-activated' cytolysins produced by Gram-positive bacteria, although Gvh does not truly belong to this family, being deactivated by beta-mercaptoethanol and being antigenically distinct from them. We report here for the first time the detection in the vaginal fluid of infected women of a specific IgA response against the toxin.
Collapse
Affiliation(s)
- S Cauci
- Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Italy
| | | | | | | | | | | | | |
Collapse
|
42
|
Bezrukov SM, Kasianowicz JJ. Current noise reveals protonation kinetics and number of ionizable sites in an open protein ion channel. PHYSICAL REVIEW LETTERS 1993; 70:2352-2355. [PMID: 10053539 DOI: 10.1103/physrevlett.70.2352] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
43
|
Tomita T, Watanabe M, Yarita Y. Assembly and channel-forming activity of a naturally-occurring nicked molecule of Staphylococcus aureus alpha-toxin. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1145:51-7. [PMID: 8422412 DOI: 10.1016/0005-2736(93)90380-i] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
From the culture supernatant of Staphylococcus aureus Wood 46, we obtained a naturally-occurring nicked molecule of staphylococcal alpha-toxin. The nicked alpha-toxin consisted of non-covalently-linked 8-kDa and 25-kDa polypeptides, which were derived, respectively, from the N-terminal and the C-terminal part of the toxin nicked at the peptide bond between Glu-71 and Gly-72. The nicked toxin, as well as native alpha-toxin, bound to and oligomerized in the liposome membranes composed of choline-containing phospholipids (i.e., phosphatidylcholine and sphingomyelin) and cholesterol, and formed membrane channel in the liposome membranes. However, the channel-forming activity of the nicked toxin, assessed as a toxin-induced carboxyfluorescein leakage from the liposomes, was approx. 20-fold lower than that of native alpha-toxin. Channel-forming activity of the nicked toxin as well as native toxin was inhibited by divalent cations including Zn2+, Cd2+, Ca2+ and Mg2+, and degree of the inhibitory effect of the divalent cations was in the following order: Zn2+ > Cd2+ > Ca2+ > Mg2+. Thus, although the cleavage of alpha-toxin at the position between Glu-71 and Gly-72 drastically reduced channel-forming activity of the toxin, the nicked toxin retained the ability to oligomerize in phospholipid-cholesterol membranes and the characteristics of channel-forming activity in terms of the specificity for phospholipids and the susceptibility to divalent cations.
Collapse
Affiliation(s)
- T Tomita
- Institute of Medical Science, University of Tokyo, Japan
| | | | | |
Collapse
|
44
|
Belmonte G, Pederzolli C, Macek P, Menestrina G. Pore formation by the sea anemone cytolysin equinatoxin II in red blood cells and model lipid membranes. J Membr Biol 1993; 131:11-22. [PMID: 7679444 DOI: 10.1007/bf02258530] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The interaction of Actinia equina equinatoxin II (EqT-II) with human red blood cells (HRBC) and with model lipid membranes was studied. It was found that HRBC hemolysis by EqT-II is the result of a colloid-osmotic shock caused by the opening of toxin-induced ionic pores. In fact, hemolysis can be prevented by osmotic protectants of adequate size. The functional radius of the lesion was estimated to be about 1.1 nm. EqT-II increased also the permeability of calcein-loaded lipid vesicles comprised of different phospholipids. The rate of permeabilization rised when sphingomyelin was introduced into the vesicles, but it was also a function of the pH of the medium, optimum activity being between pH 8 and 9; at pH 10 the toxin became markedly less potent. From the dose-dependence of the permeabilization it was inferred that EqT-II increases membrane permeability by forming oligomeric channels comprising several copies of the cytolysin monomer. The existence of such oligomers was directly demonstrated by chemical cross-linking. Addition of EqT-II to one side of a planar lipid membrane (PLM) increases the conductivity of the film in discrete steps of defined amplitude indicating the formation of cation-selective channels. The conductance of the channel is consistent with the estimated size of the lesion formed in HRBC. High pH and sphingomyelin promoted the interaction even in this system. Chemical modification of lysine residues or carboxyl groups of this protein changed the conductance, the ion selectivity and the current-voltage characteristic of the pore, suggesting that both these groups were present in its lumen.
Collapse
Affiliation(s)
- G Belmonte
- Dipartimento di Fisica, Universitá di Trento, Povo, Italy
| | | | | | | |
Collapse
|
45
|
Mangel A, Leitão JM, Batel R, Zimmermann H, Müller WE, Schröder HC. Purification and characterization of a pore-forming protein from the marine sponge Tethya lyncurium. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:499-507. [PMID: 1281099 DOI: 10.1111/j.1432-1033.1992.tb17448.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A pore-forming protein was detected and purified for the first time from a marine sponge (Tethya lyncurium). The purified protein has a polypeptide molecular mass of 21 kDa and a pI of 6.4. Tethya pore-forming protein (also called Tethya hemolysin) rapidly lysed erythrocytes from a variety of organisms. After binding to target membranes, the hemolysin resisted elution with EDTA, salt or solutions of low ionic strength and hence resembled an integral membrane protein. Erythrocytes could be protected from hemolysis induced by Tethya hemolysin by addition of 30 mM dextran 4 (4-6 kDa; equivalent hydrodynamic diffusion radius, 1.75-2.3 nm) to the extracellular medium, but not by addition of uncharged molecules of smaller size [sucrose, raffinose and poly(ethylene glycol) 1550; equivalent hydrodynamic diffusion radii, 0.46, 0.57 and 1.2 nm, respectively]. This result indicates that hemolysin is able to form stable transmembrane pores with an effective diameter of about 2-3 nm. Treatment of osmotically protected erythrocytes with Tethya hemolysin caused a rapid efflux of intracellular K+ and ATP, and a rapid influx of extracellularly added Ca2+ and sucrose. In negative-staining electron microscopy, target erythrocyte membranes exposed to purified Tethya hemolysin displayed ultrastructural lesions but without visible pores.
Collapse
Affiliation(s)
- A Mangel
- Institut für Physiologische Chemie, Universität Mainz, Federal Republic of Germany
| | | | | | | | | | | |
Collapse
|
46
|
Menestrina G. Ion transport and selectivity in model lipid membranes carrying incorporated cytolytic protein toxins. J Radioanal Nucl Chem 1992. [DOI: 10.1007/bf02037491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
47
|
Moran O, Zegarra-Moran O, Virginio C, Gusmani L, Rottini GD. Physical characterization of the pore forming cytolysine from Gardnerella vaginalis. FEMS MICROBIOLOGY IMMUNOLOGY 1992; 5:63-9. [PMID: 1384598 DOI: 10.1111/j.1574-6968.1992.tb05888.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The cytolytic toxin (CTox) produced by Gardnerella vaginalis is able to form voltage-dependent cationic channels when incorporated in lipid membranes (Moran et al. (1991) FEBS Lett. 283, 317-320). Osmotic protection experiments show that toxin incorporated in human erythrocytes forms pores between 18 A and 28 A in diameter. A hypothesis of pore formation as a primary event to produce cytolysis is proposed. The CTox activity increases when cells are depolarized by increasing the extracellular K+ concentration, probably reflecting the voltage dependent character of CTox formed channels. The cytolytic effect of the toxin was prevented by low temperatures and was a function of the extracellular Ca2+ concentration, suggesting a Ca2+ influx as part of the lytic mechanism. Binding of CTox to erythrocytes was dependent on external Ca2+ and was less temperature-dependent. Dose-response analysis suggests cooperativity of the toxin for the lytic activity, although no direct evidence of oligomerization has been found.
Collapse
Affiliation(s)
- O Moran
- Settore di Biofisica, SISSA, Trieste, Italy
| | | | | | | | | |
Collapse
|
48
|
Influence of membrane fluidity on the assembly of Staphylococcus aureus alpha-toxin, a channel-forming protein, in liposome membrane. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42223-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
49
|
Walker B, Krishnasastry M, Zorn L, Kasianowicz J, Bayley H. Functional expression of the alpha-hemolysin of Staphylococcus aureus in intact Escherichia coli and in cell lysates. Deletion of five C-terminal amino acids selectively impairs hemolytic activity. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50103-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
|
50
|
Tokunaga H, Nakae T. Calcium ion-mediated regulation of the alpha-toxin pore of Staphylococcus aureus. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1105:125-30. [PMID: 1567891 DOI: 10.1016/0005-2736(92)90170-q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The water-soluble alpha-toxin monomers of Staphylococcus aureus become hexamers forming the transmembrane pore when exposed to the membranes. This pore is freely permeable to small hydrophilic molecules, e.g. carboxyfluorescein, and becomes less permeable in the presence of calcium ions. Calcium ion-mediated decrease of the carboxyfluorescein leakage could not be eliminated by EDTA added in the medium, but the carboxyfluorescein could be freed by EDTA added in the intraliposomal space. This result suggests that the alpha-toxin pore changes its conformation as the calcium ion is bound and that the binding site is exposed to the intraliposomal side of the membrane. The interaction between the alpha-toxin hexamer and 8-anilino-1-naphthalene-sulfonic acid (ANS) was monitored by determining the fluorescence in the presence and absence of calcium chloride. The mean distances between the tryptophan residues of the alpha-toxin hexamer and the bound ANS were calculated to be 1.90 and 1.80 nm in the absence and presence, respectively, of calcium ions. The results showed the calcium ion mediated conformational change of the membrane-embedded alpha-toxin hexamer.
Collapse
Affiliation(s)
- H Tokunaga
- Department of Cellular Information Sciences, Tokai University School of Medicine, Isehara, Japan
| | | |
Collapse
|