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Zhao C, Porter JM, Burke PC, Arnberg N, Smith JG. Alpha-defensin binding expands human adenovirus tropism. PLoS Pathog 2024; 20:e1012317. [PMID: 38900833 PMCID: PMC11230588 DOI: 10.1371/journal.ppat.1012317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 07/08/2024] [Accepted: 06/04/2024] [Indexed: 06/22/2024] Open
Abstract
Mammalian α-defensins are a family of abundant effector peptides of the mucosal innate immune system. Although primarily considered to be antimicrobial, α-defensins can increase rather than block infection by certain prominent bacterial and viral pathogens in cell culture and in vivo. We have shown previously that exposure of mouse and human adenoviruses (HAdVs) to α-defensins is able to overcome competitive inhibitors that block cell binding, leading us to hypothesize a defensin-mediated binding mechanism that is independent of known viral receptors. To test this hypothesis, we used genetic approaches to demonstrate that none of several primary receptors nor integrin co-receptors are needed for human α-defensin-mediated binding of HAdV to cells; however, infection remains integrin dependent. Thus, our studies have revealed a novel pathway for HAdV binding to cells that bypasses viral primary receptors. We speculate that this pathway functions in parallel with receptor-mediated entry and contributes to α-defensin-enhanced infection of susceptible cells. Remarkably, we also found that in the presence of α-defensins, HAdV tropism is expanded to non-susceptible cells, even when viruses are exposed to a mixture of both susceptible and non-susceptible cells. Therefore, we propose that in the presence of sufficient concentrations of α-defensins, such as in the lung or gut, integrin expression rather than primary receptor expression will dictate HAdV tropism in vivo. In summary, α-defensins may contribute to tissue tropism not only through the neutralization of susceptible viruses but also by allowing certain defensin-resistant viruses to bind to cells independently of previously described mechanisms.
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Affiliation(s)
- Cheng Zhao
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Jessica M. Porter
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Phillip C. Burke
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Niklas Arnberg
- Department of Clinical Microbiology, Division of Virology and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Jason G. Smith
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, United States of America
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2
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Zhao C, Porter JM, Burke PC, Arnberg N, Smith JG. Alpha-defensin binding expands human adenovirus tropism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596681. [PMID: 38854108 PMCID: PMC11160700 DOI: 10.1101/2024.05.30.596681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Mammalian α-defensins are a family of abundant effector peptides of the mucosal innate immune system. Although primarily considered to be antimicrobial, α-defensins can increase rather than block infection by certain prominent bacterial and viral pathogens in cell culture and in vivo . We have shown previously that exposure of mouse and human adenoviruses (HAdVs) to α-defensins is able to overcome competitive inhibitors that block cell binding, leading us to hypothesize a defensin-mediated binding mechanism that is independent of known viral receptors. To test this hypothesis, we used genetic approaches to demonstrate that none of several primary receptors nor integrin co-receptors are needed for human α-defensin-mediated binding of HAdV to cells; however, infection remains integrin dependent. Thus, our studies have revealed a novel pathway for HAdV binding to cells that bypasses viral primary receptors. We speculate that this pathway functions in parallel with receptor-mediated entry and contributes to α-defensin-enhanced infection of susceptible cells. Remarkably, we also found that in the presence of α-defensins, HAdV tropism is expanded to non-susceptible cells, even when viruses are exposed to a mixture of both susceptible and non-susceptible cells. Therefore, we propose that in the presence of sufficient concentrations of α-defensins, such as in the lung or gut, integrin expression rather than primary receptor expression will dictate HAdV tropism in vivo . In summary, α-defensins may contribute to tissue tropism not only through the neutralization of susceptible viruses but also by allowing certain defensin-resistant viruses to bind to cells independently of previously described mechanisms. Author Summary In this study, we demonstrate a novel mechanism for binding of human adenoviruses (HAdVs) to cells that is dependent upon interactions with α-defensin host defense peptides but is independent of known viral receptors and co-receptors. To block normal receptor-mediated HAdV infection, we made genetic changes to both host cells and HAdVs. Under these conditions, α-defensins restored cell binding; however, infection still required the function of HAdV integrin co-receptors. This was true for multiple types of HAdVs that use different primary receptors and for cells that are either naturally devoid of HAdV receptors or were engineered to be receptor deficient. These observations suggest that in the presence of concentrations of α-defensins that would be found naturally in the lung or intestine, there are two parallel pathways for HAdV binding to cells that converge on integrins for productive infection. Moreover, these binding pathways function independently, and both operate in mixed culture. Thus, we have found that viruses can co-opt host defense molecules to expand their tropism.
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3
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Awang T, Chairatana P, Pongprayoon P. Molecular dynamics simulations of human α-defensin 5 (HD5) crossing gram-negative bacterial membrane. PLoS One 2023; 18:e0294041. [PMID: 37988380 PMCID: PMC10662769 DOI: 10.1371/journal.pone.0294041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/24/2023] [Indexed: 11/23/2023] Open
Abstract
Human α-defensin 5 (HD5) is a cationic antimicrobial peptide exhibiting a wide range of antimicrobial activities. It plays an important role in mucosal immunity of the small intestine. HD5 exerts its bactericidal activities through multiple mechanisms, one of which involves HD5 inducing the formation of pores in the bacterial membrane, subsequently allowing the peptide to enter the bacterial cytoplasm. Nevertheless, the precise molecular intricacies underlying its bactericidal mechanisms remain inadequately understood. In this work, the Potential of Mean Force (PMF) was computed to delve into the energetic properties governing the movement of HD5 across the lipopolysaccharide (LPS) membrane, which is a representative model of the gram-negative bacterial membrane. Our findings indicate that the most favorable free energy is attained when HD5 binds to the surface of the LPS membrane. This favorable interaction is primarily driven by the strong interactions between arginine residues in HD5 and the charged head groups of LPS, serving as the predominant forces facilitating the adhesion of HD5 to the membrane. Our analysis reveals that a dimeric form of HD5 alone is sufficient to create a water-filled channel in the membrane; however, achieving the complete lysis of the gram-negative bacterial membrane requires higher-order oligomerization of HD5. Our results suggest that HD5 employs the toroidal pore formation mechanism to disrupt the integrity of the LPS membrane. Furthermore, we identified that the primary energy barrier obstructing HD5 from traversing the membrane is localized within the hydrophobic core of the membrane, which is also observed for other defensins. Additionally, our study demonstrates that a mixture of HD5-LPS leads to a thinning of the membrane. Taken together, this work provides a deeper insight into the molecular intricacies governing the behavior of HD5 as it translocates through the gram-negative bacterial membrane.
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Affiliation(s)
- Tadsanee Awang
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Phoom Chairatana
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Prapasiri Pongprayoon
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, KU Institute for Advanced Studies, Kasetsart University, Bangkok, Thailand
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4
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Fu J, Zong X, Jin M, Min J, Wang F, Wang Y. Mechanisms and regulation of defensins in host defense. Signal Transduct Target Ther 2023; 8:300. [PMID: 37574471 PMCID: PMC10423725 DOI: 10.1038/s41392-023-01553-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 04/11/2023] [Accepted: 06/26/2023] [Indexed: 08/15/2023] Open
Abstract
As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.
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Affiliation(s)
- Jie Fu
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, Hangzhou, Zhejiang Province, China
| | - Xin Zong
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, Hangzhou, Zhejiang Province, China
| | - Mingliang Jin
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, Hangzhou, Zhejiang Province, China
| | - Junxia Min
- The First Affiliated Hospital, Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Fudi Wang
- The Second Affiliated Hospital, School of Public Health, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China.
- The First Affiliated Hospital, Basic Medical Sciences, School of Public Health, Hengyang Medical School, University of South China, Hengyang, China.
| | - Yizhen Wang
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou, China.
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, Hangzhou, Zhejiang Province, China.
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Porter JM, Oswald MS, Sharma A, Emmanuel S, Kansol A, Bennett A, McKenna R, Smith JG. A Single Surface-Exposed Amino Acid Determines Differential Neutralization of AAV1 and AAV6 by Human Alpha-Defensins. J Virol 2023; 97:e0006023. [PMID: 36916912 PMCID: PMC10062168 DOI: 10.1128/jvi.00060-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/21/2023] [Indexed: 03/16/2023] Open
Abstract
Adeno-associated viruses (AAVs) are being developed as gene therapy vectors due to their low pathogenicity and tissue tropism properties. However, the efficacy of these vectors is impeded by interactions with the host immune system. One potential immune barrier to vector transduction is innate immune host defense peptides, such as alpha-defensins, which are potent antiviral agents against other nonenveloped viruses. To investigate the interaction between AAVs and alpha-defensins, we utilized two closely related AAV serotypes, AAV1 and AAV6. Although their capsids differ by only six residues, these two serotypes exhibit markedly different tissue tropisms and transduction efficiencies. Using two abundant human alpha-defensins, enteric human defensin 5 (HD5) and myeloid human neutrophil peptide 1 (HNP1), we found both serotype-specific and defensin-specific effects on AAV infection. AAV6 infection was uniformly neutralized by both defensins at low micromolar concentrations; however, inhibition of AAV1 infection was profoundly influenced by the timing of defensin exposure to the virus relative to viral attachment to the cell. Remarkably, these differences in the defensin-dependent infection phenotype between the viruses are completely dictated by the identity of a single, surface-exposed amino acid (position 531) that varies between the two serotypes. These findings reveal a determinant for defensin activity against a virus with unprecedented precision. Furthermore, they provide a rationale for the investigation of other AAV serotypes not only to understand the mechanism of neutralization of defensins against AAVs but also to design more efficient vectors. IMPORTANCE The ability of adeno-associated viruses (AAVs) to infect and deliver genetic material to a range of cell types makes them favorable gene therapy vectors. However, AAV vectors encounter a wide variety of host immune factors throughout the body, which can impede efficient gene delivery. One such group of factors is the alpha-defensins, which are a key component of the innate immune system that can directly block viral infection. By studying the impact that alpha-defensins have on AAV infection, we found that two similar AAV serotypes (AAV1 and AAV6) have different sensitivities to inhibition. We also identified a single amino acid (position 531) that differs between the two AAV serotypes and is responsible for mediating their defensin sensitivity. By investigating the effects that host immune factors have on AAV infection, more efficient vectors may be developed to evade intervention by the immune system prior to gene delivery.
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Affiliation(s)
- Jessica M. Porter
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Mackenzi S. Oswald
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Anjali Sharma
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Shanan Emmanuel
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Austin Kansol
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Antonette Bennett
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Jason G. Smith
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
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6
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Akahoshi DT, Natwick DE, Yuan W, Lu W, Collins SR, Bevins CL. Flagella-driven motility is a target of human Paneth cell defensin activity. PLoS Pathog 2023; 19:e1011200. [PMID: 36821624 PMCID: PMC9990921 DOI: 10.1371/journal.ppat.1011200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/07/2023] [Accepted: 02/10/2023] [Indexed: 02/24/2023] Open
Abstract
In the mammalian intestine, flagellar motility can provide microbes competitive advantage, but also threatens the spatial segregation established by the host at the epithelial surface. Unlike microbicidal defensins, previous studies indicated that the protective activities of human α-defensin 6 (HD6), a peptide secreted by Paneth cells of the small intestine, resides in its remarkable ability to bind microbial surface proteins and self-assemble into protective fibers and nets. Given its ability to bind flagellin, we proposed that HD6 might be an effective inhibitor of bacterial motility. Here, we utilized advanced automated live cell fluorescence imaging to assess the effects of HD6 on actively swimming Salmonella enterica in real time. We found that HD6 was able to effectively restrict flagellar motility of individual bacteria. Flagellin-specific antibody, a classic inhibitor of flagellar motility that utilizes a mechanism of agglutination, lost its activity at low bacterial densities, whereas HD6 activity was not diminished. A single amino acid variant of HD6 that was able to bind flagellin, but not self-assemble, lost ability to inhibit flagellar motility. Together, these results suggest a specialized role of HD6 self-assembly into polymers in targeting and restricting flagellar motility.
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Affiliation(s)
- Douglas T. Akahoshi
- Department of Microbiology and Immunology, School of Medicine, University of California Davis, Davis, California, United States of America
| | - Dean E. Natwick
- Department of Microbiology and Molecular Genetics, University of California Davis, Davis, California, United States of America
| | - Weirong Yuan
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Sean R. Collins
- Department of Microbiology and Molecular Genetics, University of California Davis, Davis, California, United States of America
| | - Charles L. Bevins
- Department of Microbiology and Immunology, School of Medicine, University of California Davis, Davis, California, United States of America
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7
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Mouse α-Defensins: Structural and Functional Analysis of the 17 Cryptdin Isoforms Identified from a Single Jejunal Crypt. Infect Immun 2023; 91:e0036122. [PMID: 36472443 PMCID: PMC9872612 DOI: 10.1128/iai.00361-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mouse α-defensins, better known as cryptdins, are host protective antimicrobial peptides produced in the intestinal crypt by Paneth cells. To date, more than 20 cryptdin mRNAs have been identified from mouse small intestine, of which the first six cryptdins (Crp1 to Crp6) have been isolated and characterized at the peptide level. We quantified bactericidal activities against Escherichia coli and Staphylococcus aureus of the 17 cryptdin isoforms identified by Ouellette and colleagues from a single jejunal crypt (A. J. Ouellette et al., Infect Immun 62:5040-5047, 1994), along with linearized analogs of Crp1, Crp4, and Crp14. In addition, we analyzed the most potent and weakest cryptdins in the panel with respect to their ability to self-associate in solution. Finally, we solved, for the first time, the high-resolution crystal structure of a cryptdin, Crp14, and performed molecular dynamics simulation on Crp14 and a hypothetical mutant, T14K-Crp14. Our results indicate that mutational effects are highly dependent on cryptdin sequence, residue position, and bacterial strain. Crp14 adopts a disulfide-stabilized, three-stranded β-sheet core structure and forms a noncanonical dimer stabilized by asymmetrical interactions between the two β1 strands in parallel. The killing of E. coli by cryptdins is generally independent of their tertiary and quaternary structures that are important for the killing of S. aureus, which is indicative of two distinct mechanisms of action. Importantly, sequence variations impact the bactericidal activity of cryptdins by influencing their ability to self-associate in solution. This study expands our current understanding of how cryptdins function at the molecular level.
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8
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Zhou F, Pan W, Chang Y, Su X, Duan X, Xue Q. A Supported Lipid Bilayer-Based Lab-on-a-Chip Biosensor for the Rapid Electrical Screening of Coronavirus Drugs. ACS Sens 2022; 7:2084-2092. [PMID: 35735978 PMCID: PMC9236208 DOI: 10.1021/acssensors.2c00970] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/15/2022] [Indexed: 01/06/2023]
Abstract
With the rapid spread and multigeneration variation of coronavirus, rapid drug development has become imperative. A major obstacle to addressing this issue is adequately constructing the cell membrane at the molecular level, which enables in vitro observation of the cell response to virus and drug molecules quantitatively, shortening the drug experiment cycle. Herein, we propose a rapid and label-free supported lipid bilayer-based lab-on-a-chip biosensor for the screening of effective inhibition drugs. An extended gate electrode was prepared and functionalized by an angiotensin-converting enzyme II (ACE2) receptor-incorporated supported lipid bilayer (SLB). Such an integrated system can convert the interactions of targets and membrane receptors into real-time charge signals. The platform can simulate the cell membrane microenvironment in vitro and accurately capture the interaction signal between the target and the cell membrane with minimized interference, thus observing the drug action pathway quantitatively and realizing drug screening effectively. Due to these label-free, low-cost, convenient, and integrated advantages, it is a suitable candidate method for the rapid drug screening for the early treatment and prevention of worldwide spread of coronavirus.
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Affiliation(s)
- Feng Zhou
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
| | - Wenwei Pan
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
| | - Ye Chang
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
| | - Xueyou Su
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
| | - Xuexin Duan
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
| | - Qiannan Xue
- State Key Laboratory of Precision Measuring Technology & Instruments,
School of Precision Instruments and Optoelectronics Engineering, Tianjin
University, Tianjin 300072, China
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9
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Chumponanomakun P, Niramitranon J, Chairatana P, Pongprayoon P. Molecular insights into the adsorption mechanism of E21R and T7E21R human defensin 5 on a bacterial membrane. MOLECULAR SIMULATION 2022. [DOI: 10.1080/08927022.2022.2086253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Phoom Chumponanomakun
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Jitti Niramitranon
- Department of Computer Engineering, Faculty of Engineering, Kasetsart University, Bangkok, Thailand
| | - Phoom Chairatana
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Prapasiri Pongprayoon
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, KU Institute for Advanced Studies, Kasetsart University, Bangkok, Thailand
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10
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Abstract
We report the development of peptidomimetic antibiotics derived from a natural antimicrobial peptide, human α-defensin 5. By engaging multiple bacterial targets, the lead compound is efficacious in vitro and in vivo against bacteria with highly inducible antibiotic resistance, promising a useful therapeutic agent for the treatment of infections caused by antibiotic-resistant bacteria. Antibiotics with multiple mechanisms of action and broad-spectrum are urgently required to combat the growing health threat posed by resistant pathogenic microorganisms. Combining computational and medicinal chemistry tools, we used the structure of human α-defensin 5 (HD5) to design a class of peptidomimetic antibiotics with improved activity against both gram-negative and gram-positive bacteria. The most promising lead, compound 10, showed potent killing of multiple drug-resistant gram-negative bacteria isolated from patients. Compound 10 exhibited a multiplex mechanism of action through targeting membrane components—outer membrane protein A and lipopolysaccharide, as well as a potential intracellular target—70S ribosome, thus causing membrane perturbation and inhibition of protein synthesis. In vivo efficacy, stability, and safety of compound 10 were also validated. This human defensin-inspired synthetic peptidomimetic could help solve the serious problem of drug resistance to conventional antibiotics.
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11
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Gao X, Ding J, Liao C, Xu J, Liu X, Lu W. Defensins: The natural peptide antibiotic. Adv Drug Deliv Rev 2021; 179:114008. [PMID: 34673132 DOI: 10.1016/j.addr.2021.114008] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/28/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022]
Abstract
Defensins are a family of cationic antimicrobial peptides active against a broad range of infectious microbes including bacteria, viruses and fungi, playing important roles as innate effectors and immune modulators in immunological control of microbial infection. Their antibacterial properties and unique mechanisms of action have garnered considerable interest in developing defensins into a novel class of natural antibiotic peptides to fend off pathogenic infection by bacteria, particularly those resistant to conventional antibiotics. However, serious pharmacological and technical obstacles, some of which are unique to defensins and others are common to peptide drugs in general, have hindered the development and clinical translation of defensins as anti-infective therapeutics. To overcome them, several technologies have been developed, aiming for improved functionality, prolonged circulation time, enhanced proteolytic stability and bioavailability, and efficient and controlled delivery and release of defensins to the site of infection. Additional challenges include the alleviation of potential toxicity of defensins and their cost-effective manufacturing. In this review, we briefly introduce defensin biology, focus on various transforming strategies and practical techniques developed for defensins and their derivatives as antibacterial therapeutics, and conclude with a summation of future challenges and possible solutions.
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12
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Evaluation of the Binding Mechanism of Human Defensin 5 in a Bacterial Membrane: A Simulation Study. Int J Mol Sci 2021; 22:ijms222212401. [PMID: 34830284 PMCID: PMC8619297 DOI: 10.3390/ijms222212401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/11/2021] [Accepted: 11/15/2021] [Indexed: 12/27/2022] Open
Abstract
Human α-defensin 5 (HD5) is a host-defense peptide exhibiting broad-spectrum antimicrobial activity. The lipopolysaccharide (LPS) layer on the Gram-negative bacterial membrane acts as a barrier to HD5 insertion. Therefore, the pore formation and binding mechanism remain unclear. Here, the binding mechanisms at five positions along the bacterial membrane axis were investigated using Molecular Dynamics. (MD) simulations. We found that HD5 initially placed at positions 1 to 3 moved up to the surface, while HD5 positioned at 4 and 5 remained within the membrane interacting with the middle and inner leaflet of the membrane, respectively. The arginines were key components for tighter binding with 3-deoxy-d-manno-octulosonic acid (KDO), phosphates of the outer and inner leaflets. KDO appeared to retard the HD5 penetration.
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13
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Awang T, Pongprayoon P. The penetration of human defensin 5 (HD5) through bacterial outer membrane: simulation studies. J Mol Model 2021; 27:291. [PMID: 34546425 DOI: 10.1007/s00894-021-04915-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/13/2021] [Indexed: 11/24/2022]
Abstract
Human α-defensin 5 (HD5) is one of cationic antimicrobial peptides which plays a crucial role in an innate immune system in human body. HD5 shows the killing activity against a broad spectrum of pathogenic bacteria by making a pore in a bacterial membrane and penetrating into a cytosol. Nonetheless, its pore-forming mechanisms remain unclear. Thus, in this work, the constant-velocity steered molecular dynamics (SMD) simulation was used to simulate the permeation of a dimeric HD5 into a gram-negative lipopolysaccharide (LPS) membrane model. Arginine-rich HD5 is found to strongly interact with a LPS surface. Upon arrival, arginines on HD5 interact with lipid A head groups (a top part of LPS) and then drag these charged moieties down into a hydrophobic core resulting in the formation of water-filled pore. Although all arginines are found to interact with a membrane, Arg13 and Arg32 appear to play a dominant role in the HD5 adsorption on a gram-negative membrane. Furthermore, one chain of a dimeric HD5 is required for HD5 adhesion. The interactions of arginine-lipid A head groups play a major role in adhering a cationic HD5 on a membrane surface and retarding a HD5 passage in the meantime.
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Affiliation(s)
- Tadsanee Awang
- Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Prapasiri Pongprayoon
- Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand. .,Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, KU Institute for Advanced Studies, Kasetsart University, Bangkok, 10900, Thailand.
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14
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Alkaissi LY, Winberg ME, Heil SDS, Haapaniemi S, Myrelid P, Stange EF, Söderholm JD, Keita ÅV. Antagonism of Adherent Invasive E. coli LF82 With Human α-defensin 5 in the Follicle-associated Epithelium of Patients With Ileal Crohn's Disease. Inflamm Bowel Dis 2020; 27:1116-1127. [PMID: 33336693 PMCID: PMC8205628 DOI: 10.1093/ibd/izaa315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND The first visible signs of Crohn's disease (CD) are microscopic erosions over the follicle-associated epithelium (FAE). The aim of the study was to investigate the effects of human α-defensin 5 (HD5) on adherent-invasive Escherichia coli LF82 translocation and HD5 secretion after LF82 exposure in an in vitro model of human FAE and in human FAE ex vivo. METHODS An in vitro FAE-model was set up by the coculture of Raji B cells and Caco-2-cl1 cells. Ileal FAE from patients with CD and controls were mounted in Ussing chambers. The effect of HD5 on LF82 translocation was studied by LF82 exposure to the cells or tissues with or without incubation with HD5. The HD5 secretion was measured in human FAE exposed to LF82 or Salmonella typhimurium. The HD5 levels were evaluated by immunofluorescence, immunoblotting, and ELISA. RESULTS There was an increased LF82 translocation across the FAE-model compared with Caco-2-cl1 (P < 0.05). Incubation of cell/tissues with HD5 before LF82 exposure reduced bacterial passage in both models. Human FAE showed increased LF82 translocation in CD compared with controls and attenuated passage after incubation with sublethal HD5 in both CD and controls (P < 0.05). LF82 exposure resulted in a lower HD5 secretion in CD FAE compared with controls (P < 0.05), whereas Salmonella exposure caused equal secretion on CD and controls. There were significantly lower HD5 levels in CD tissues compared with controls. CONCLUSIONS Sublethal HD5 reduces the ability of LF82 to translocate through FAE. The HD5 is secreted less in CD in response to LF82, despite a normal response to Salmonella. This further implicates the integrated role of antimicrobial factors and barrier function in CD pathogenesis.
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Affiliation(s)
- Lina Y Alkaissi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Martin E Winberg
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Stéphanie D S Heil
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Staffan Haapaniemi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden,Department of Surgery, Vrinnevi Hospital, Norrköping, Sweden
| | - Pär Myrelid
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden,Department of Surgery, Linköping University, Linköping, Sweden
| | - Eduard F Stange
- Department of Gastroenterology, Dept. Internal Medicine I, University of Tübingen, 72076 Tübingen, Germany
| | - Johan D Söderholm
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden,Department of Surgery, Linköping University, Linköping, Sweden
| | - Åsa V Keita
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden,Address correspondence to: Åsa V. Keita, PhD, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics & Oncology, Medical Faculty, Linköping University, 581 85 Linköping, Sweden. E-mail:
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15
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Abstract
Defensins are a major family of host defense peptides expressed predominantly in neutrophils and epithelial cells. Their broad antimicrobial activities and multifaceted immunomodulatory functions have been extensively studied, cementing their role in innate immunity as a core host-protective component against bacterial, viral and fungal infections. More recent studies, however, paint defensins in a bad light such that they are "alleged" to promote viral and bacterial infections in certain biological settings. This mini review summarizes the latest findings on the potential pathogenic properties of defensins against the backdrop of their protective roles in antiviral and antibacterial immunity. Further, a succinct description of both tumor-proliferative and -suppressive activities of defensins is also given to highlight their functional and mechanistic complexity in antitumor immunity. We posit that given an enabling environment defensins, widely heralded as the "Swiss army knife," can function as a "double-edged sword" in host immunity.
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Affiliation(s)
- Dan Xu
- Institute of Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Sciences and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, United States
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16
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Zhao G, Chen Y, He Y, Chen F, Gong Y, Chen S, Xu Y, Su Y, Wang C, Wang J. Succinylated casein-coated peptide-mesoporous silica nanoparticles as an antibiotic against intestinal bacterial infection. Biomater Sci 2019; 7:2440-2451. [PMID: 30939184 DOI: 10.1039/c9bm00003h] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Increasing drug resistance necessitates the discovery of novel bactericides. Human defensin (HD) peptides can eliminate resistant bacteria and are promising candidates for next-generation antibiotics. T7E21R-HD5 is a potent bactericide designed by site mutations at enteric HD5. To facilitate the development of T7E21R-HD5 into an intestinal antibiotic, we employed a mesoporous silica nanoparticle (MSN) as the peptide carrier. Despite its ineffectiveness at killing bacteria, the MSN intensified the outer membrane penetration and inner membrane permeabilization abilities of T7E21R-HD5 and thus enhanced its antibacterial action against multidrug resistant (MDR) E. coli, which broadened the role of MSNs in drug delivery. For the reduction in T7E21R-HD5 losses in the stomach, we further modified MSN@T7E21R-HD5 with succinylated casein (SCN), a milk protein that can be specifically degraded by intestinal protease. SCN coating decreased T7E21R-HD5 release from the MSNs, especially in a highly acidic environment. The controlled release of MSN@T7E21R-HD5 from SCN encapsulation was confirmed in the presence of trypsin. MSN@T7E21R-HD5@SCN was nontoxic to host cells, and it was capable of inactivating MDR E. coli in vivo and alleviating intestinal inflammation by suppressing the production of inflammatory factors TNF-α, IL-1β, and MMP-9. This study provides a peptide-based nanobiotic with efficacy to combat intestinal infection, especially against drug-resistant bacteria. The biocompatible and readily prepared MSN/SCN delivery system may benefit further intestinal antibiotic design and promote the drug transformation of additional enterogenic functional molecules.
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Affiliation(s)
- Gaomei Zhao
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.
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17
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Human Enteric Defensin 5 Promotes Shigella Infection of Macrophages. Infect Immun 2019; 88:IAI.00769-19. [PMID: 31611271 DOI: 10.1128/iai.00769-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 10/06/2019] [Indexed: 01/13/2023] Open
Abstract
Human α-defensins are 3- to 5-kDa disulfide-bridged peptides with a multitude of antimicrobial activities and immunomodulatory functions. Recent studies show that human enteric α-defensin 5 (HD5), a host defense peptide important for intestinal homeostasis and innate immunity, aids the highly infectious enteropathogen Shigella in breaching the intestinal epithelium in vitro and in vivo Whether and how HD5 influences Shigella infection of resident macrophages following its invasion of the intestinal epithelium remain poorly understood. Here, we report that HD5 greatly promoted phagocytosis of Shigella by macrophages by targeting the bacteria to enhance bacterium-to-cell contacts in a structure- and sequence-dependent fashion. Subsequent intracellular multiplication of phagocytosed Shigella led to massive necrotic cell death and release of the bacteria. HD5-promoted phagocytosis of Shigella was independent of the status of the type 3 secretion system. Furthermore, HD5 neither inhibited nor enhanced phagosomal escape of Shigella Collectively, these findings confirm a potential pathogenic role of HD5 in Shigella infection of not only epithelial cells but also macrophages, illuminating how an enteropathogen exploits a host protective factor for virulence and infection.
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18
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Gulati NM, Miyagi M, Wiens ME, Smith JG, Stewart PL. α-Defensin HD5 Stabilizes Human Papillomavirus 16 Capsid/Core Interactions. Pathog Immun 2019; 4:196-234. [PMID: 31583330 PMCID: PMC6755940 DOI: 10.20411/pai.v4i2.314] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 08/17/2019] [Indexed: 12/17/2022] Open
Abstract
Background: Human papillomavirus (HPV) is linked to nearly all cases of cervical cancer. Despite available vaccines, a deeper understanding of the immune response to HPV is needed. Human α-defensin 5 (HD5), an innate immune effector peptide, blocks infection of multiple sero-types of HPV, including high-risk HPV16. While a common mechanism of α-defensin anti-viral activity against nonenveloped viruses such as HPV has emerged, there is limited understanding of how α-defensins bind to viral capsids to block infection. Methods: We have used cryo-electron microscopy (cryoEM), mass spectrometry (MS) crosslinking and differential lysine modification studies, and molecular dynamics (MD) simulations to probe the interaction of HPV16 pseudovirions (PsVs) with HD5. Results: CryoEM single particle reconstruction did not reveal HD5 density on the capsid surface. Rather, increased density was observed under the capsid shell in the presence of HD5. MS studies indicate that HD5 binds near the L1 and L2 capsid proteins and specifically near the C-terminal region of L1. MD simulations indicate that favorable electrostatic interactions can be formed between HD5 and the L1 C-terminal tail. Conclusions: A model is presented for how HD5 affects HPV16 structure and cell entry. In this model, HD5 binds to disordered regions of L1 and L2 protruding from the icosahedrally ordered capsid. HD5 acts to cement interactions between L1 and L2 and leads to a closer association of the L2/genome core with the L1 capsid. This model provides a structural rationale for our prior observation that HD5 interferes with the separation of L1 from the L2/genome complex during cell entry. Graphical Abstract
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Affiliation(s)
- Neetu M Gulati
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.,Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio
| | - Masaru Miyagi
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio
| | - Mayim E Wiens
- Department of Microbiology, University of Washington, Seattle, Washington
| | - Jason G Smith
- Department of Microbiology, University of Washington, Seattle, Washington
| | - Phoebe L Stewart
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.,Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio
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19
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Antimicrobial peptide ROAD-1 triggers phase change in local membrane environment to execute its activity. J Mol Model 2019; 25:281. [PMID: 31468141 DOI: 10.1007/s00894-019-4163-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 08/15/2019] [Indexed: 10/26/2022]
Abstract
Emergence of antibiotic-resistant pathogens has paved way for development of newer class of drugs that would not be susceptible to resistance. Antimicrobial peptides such as defensins that target the microbial membrane are promising candidates. ROAD-1 is an alpha-defensin present in the oral cavity of rhesus macaque and shares very high sequence similarity to human enteric defensin 5. In this study we have performed microsecond long all atom molecular dynamic simulations to understand the mechanism of action of ROAD-1. We find that ROAD-1 is able to adopt an energetically stable conformation predominantly stabilized by electrostatic interactions only in presence of bacterial membranes. In mammalian membrane even though it gets absorbed onto the bilayer, it is unable to adopt an equilibrium conformation. Binding of ROAD-1 to bilayer induces clustering of POPG molecules up to 15 Å around the peptide. POPG molecules show higher order parameters than the neighboring POPE implying coexistence of different phases. Analysis of binding free energy of ROAD-1-membrane complex indicates Arg1, Arg2, Arg7, and Arg25 to play key role in its antimicrobial activity. Unlike its homolog HD5, ROAD-1 is not observed to form a dimer. Our study gives insight into the membrane-bound conformation of ROAD-1 and its mechanism of action that can aid in designing defensin-based therapeutics. Graphical abstract Antimicrobial peptide ROAD-1 adopts a different membrane-bound conformation as compared with HD5 even though they belong to the same family implying a different mechanism of action.
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20
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Chairatana P, Niramitranon J, Pongprayoon P. Dynamics of human defensin 5 (HD5) self-assembly in solution: Molecular simulations/insights. Comput Biol Chem 2019; 83:107091. [PMID: 31349122 DOI: 10.1016/j.compbiolchem.2019.107091] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 09/07/2018] [Accepted: 07/10/2019] [Indexed: 01/15/2023]
Abstract
Human α -defensin 5 (HD5) is a 32-residue cysteine-rich host-defense peptide that exhibits broad-spectrum antimicrobial activity and plays an essential role in innate immunity in the human gut and other organ systems. Although its antimicrobial mechanism of action remains unclear, the high salt concentration seems to attenuate the antimicrobial function of HD5 via an unknown mechanism. In this work, we employ Molecular Dynamics (MD) simulations to analyse the oligomerization behaviour of HD5 when exposed to different salt concentration. We demonstrate that the presence of salt, such as sodium chloride (NaCl), promotes HD5 to form higher-order oligomers (up to heptamers) in our simulations. In addition, we also analyse the electrostatic interactions between the two Glu residues (E14 and E21) and their neighbouring residues. Our data confirm that the E14 residue is essential for the structural integrity, whereas the E21 residue contributes to the dimerization of HD5, suggesting that these Glu residues are important for the antimicrobial function of this peptide.
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Affiliation(s)
- Phoom Chairatana
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Jitti Niramitranon
- Department of Computer engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Prapasiri Pongprayoon
- Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand; Center for Advanced Studies in Nanotechnology for Chemical, Food and Agricultural Industries, KU Institute for Advanced Studies, Kasetsart University, Bangkok, 10900, Thailand; Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Kasetsart University, Bangkok, 10900, Thailand.
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21
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Liao C, Fang K, Xiao J, Zhang W, Zhang B, Yuan W, Lu W, Xu D. Critical determinants of human neutrophil peptide 1 for enhancing host epithelial adhesion of Shigella flexneri. Cell Microbiol 2019; 21:e13069. [PMID: 31218775 DOI: 10.1111/cmi.13069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/17/2019] [Accepted: 06/04/2019] [Indexed: 11/27/2022]
Abstract
Human neutrophil peptides (HNPs), also known as human myeloid α-defensins degranulated by infiltrating neutrophils at bacterial infection loci, exhibit broad antomicrobial activities against bacteria, fungi, and viruses. We have made a surprising recent finding that Shigella, a highly contagious, yet poorly adhesive enteric pathogen, exploits human α-defensins including HNP1 to enhance its adhesion to and invasion of host epithelial cells. However, the critical molecular determinants responsible for HNP1-enhanced Shigella adhesion and invasion have yet to be investigated. Using cultured epithelial cells and polarised Caco2 cells as an in vitro infection model, we demonstrated that HNP1 promoted Shigella infection in a structure- and sequence-dependent manner, with two bulky hydrophobic residues, Trp26 and Phe28 important for HNP1 self-assembly, being most critical. The functional importance of hydrophobicity for HNP1-enhanced Shigella infection was further verified by substitutions for Trp26 of a series of unnatural amino acids with straight aliphatic side chains of different lengths. Dissection of the Shigella infection process revealed that bacteria-rather than host cells-bound HNP1 contributed most to the enhancement. Further, mutagenesis analysis of bacterial surface components, while precluding the involvement of lipopolysaccharides (LPS) in the interaction with HNP1, identified outer membrane proteins and the Type 3 secretion apparatus as putative binding targets of HNP1 involved in enhanced Shigella adhesion and invasion. Our findings provide molecular and mechanistic insights into the mode of action of HNP1 in promoting Shigella infection, thus showcasing another example of how innate immune factors may serve as a double-edged sword in health and disease.
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Affiliation(s)
- Chongbing Liao
- Center for Translational Medicine Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kun Fang
- Department of Internal Medicine, Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jiu Xiao
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Wei Zhang
- Center for Translational Medicine Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Bing Zhang
- Center for Translational Medicine Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Weirong Yuan
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dan Xu
- Center for Translational Medicine Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
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22
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Kim KC, Lee W, Lee J, Cha HJ, Hwang BH. Newly Identified HNP-F from Human Neutrophil Peptide-1 Promotes Hemostasis. Biotechnol J 2019; 14:e1800606. [PMID: 30927490 DOI: 10.1002/biot.201800606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/29/2019] [Indexed: 12/13/2022]
Abstract
Active hemostatic agents can play a crucial role in saving patients' lives during surgery. Active hemostats have several advantages including utilization of natural blood coagulation and biocompatibility. Among them, although human neutrophil peptide-1 (HNP-1) has been previously reported with the hemostatic mechanism, which part of HNP-1 facilitates the hemostatic activity is not known. Here, a partial peptide (HNP-F) promoting hemostasis, originating from HNP-1, has been newly identified by the blood coagulation ability test. HNP-F shows the best hemostatic effect between the anterior half and posterior half of peptides. Moreover, microscopic images show platelet aggregation and an increase in the concentration of platelet factor 4, and the scanning electron microscope image of platelets support platelet activation by HNP-F. Thromboelastography indicates decreased clotting time and increased physical properties of blood clotting. Mouse liver experiments demonstrate improved hemostatic effect by treatment of peptide solution. Cell viability and hemolysis assays confirm the HNP-F's biosafety. It is hypothesized that the surface charge and structure of HNP-F could be favorable to interact with fibrinogen or thrombospondin-1. Collectively, because HNP-F as an active peptide hemostat has many advantages, it could be expected to become a potent hemostatic biomaterial, additive or pharmaceutical candidate for various hemostatic applications.
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Affiliation(s)
- Ki Chan Kim
- Department of Bioengineering and Nano-Bioengineering, Incheon National University, Academy-ro 119, Yeonsu-gu, Incheon, 22012, Korea
| | - Woogi Lee
- Department of Bioengineering and Nano-Bioengineering, Incheon National University, Academy-ro 119, Yeonsu-gu, Incheon, 22012, Korea
| | - Jaeyun Lee
- Department of Chemical Engineering, POSTECH, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, Korea
| | - Hyung Joon Cha
- Department of Chemical Engineering, POSTECH, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, Korea
| | - Byeong Hee Hwang
- Department of Bioengineering and Nano-Bioengineering, Incheon National University, Academy-ro 119, Yeonsu-gu, Incheon, 22012, Korea.,Division of Bioengineering, Incheon National University, Academy-ro 119, Yeonsu-gu, Incheon, 22012, Korea
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23
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Hu H, Di B, Tolbert WD, Gohain N, Yuan W, Gao P, Ma B, He Q, Pazgier M, Zhao L, Lu W. Systematic mutational analysis of human neutrophil α-defensin HNP4. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:835-844. [PMID: 30658057 DOI: 10.1016/j.bbamem.2019.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 12/19/2018] [Accepted: 01/13/2019] [Indexed: 12/28/2022]
Abstract
Defensins are a family of cationic antimicrobial peptides of innate immunity with immunomodulatory properties. The prototypic human α-defensins, also known as human neutrophil peptides 1-3 or HNP1-3, are extensively studied for their structure, function and mechanisms of action, yet little is known about HNP4 - the much less abundant "distant cousin" of HNP1-3. Here we report a systematic mutational analysis of HNP4 with respect to its antibacterial activity against E. coli and S. aureus, inhibitory activity against anthrax lethal factor (LF), and binding activity for LF and HIV-1 gp120. Except for nine conserved and structurally important residues (6xCys, 1xArg, 1xGlu and 1xGly), the remaining 24 residues of HNP4 were each individually mutated to Ala. The crystal structures of G23A-HNP4 and T27A-HNP4 were determined, both exhibiting a disulfide-stabilized canonical α-defensin dimer identical to wild-type HNP4. Unlike HNP1-3, HNP4 preferentially killed the Gram-negative bacterium, a property largely attributable to three clustered cationic residues Arg10, Arg11 and Arg15. The cationic cluster was also important for HNP4 killing of S. aureus, inhibition of LF and binding to LF and gp120. However, F26A, while functionally inconsequential for E. coli killing, was far more deleterious than any other mutations. Similarly, N-methylation of Leu20 to destabilize the HNP4 dimer had little effect on E. coli killing, but significantly reduced the ability of HNP4 to kill S. aureus, inhibit LF, and bind to LF and gp120. Our findings unveil the molecular determinants of HNP4 function, completing the atlas of structure and function relationships for all human neutrophil α-defensins.
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Affiliation(s)
- Han Hu
- Key Laboratory of Fermentation Engineering, Ministry of Education, College of Bioengineering, Hubei University of Technology, Wuhan, China; Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Bin Di
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - William D Tolbert
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Neelakshi Gohain
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Weirong Yuan
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Pan Gao
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Bohan Ma
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
| | - Qigai He
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Marzena Pazgier
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA.
| | - Le Zhao
- Center for Translational Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
| | - Wuyuan Lu
- Institute of Human Virology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA
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24
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The adsorption of human defensin 5 on bacterial membranes: simulation studies. J Mol Model 2018; 24:273. [PMID: 30187138 DOI: 10.1007/s00894-018-3812-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/27/2018] [Indexed: 01/16/2023]
Abstract
Human α-defensin 5 (HD5) is one of the important antimicrobial peptides (AMPs) used against a broad-spectrum of pathogens, especially Gram-negative bacteria. HD5 kills by disrupting and making a pore in the bacterial membrane. The presence of lipopolysaccharide (LPS), located on a membrane surface, is found to have an impact on HD5's activity, where such binding mechanism in microscopic detail remains unclear. In this work, we therefore employed molecular dynamics (MD) simulations to investigate the binding mechanisms of HD5 on LPS in comparison to a bare DMPC lipid membrane. Two oligomers, dimer and tetramer, are studied here. Apparently, the membrane structure influences the protein binding affinity. HD5 binds tighter to a lipid membrane than LPS. Both dimeric and tetrameric HD5 can penetrate deeply into a phosphate layer in a lipid membrane, whereas only facial contacts are observed for LPS systems. The proteins appear to stay in the polar area instead of diving into a hydrophobic region. Furthermore, it happens in all cases that residues in the active region (A1, T2, R6, R13, R32) contribute to the membrane adsorption. The breakdown of tetramer into two dimers is also found. This implies that the dimer is more favorable for membrane binding. Moreover, both dimeric and tetrameric HD5 can significantly disrupt a LPS layer, whilst no serious distortion of lipid membrane is obtained. This emphasizes the importance of LPS on HD5 activity.
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25
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Lei R, Hou J, Chen Q, Yuan W, Cheng B, Sun Y, Jin Y, Ge L, Ben-Sasson SA, Chen J, Wang H, Lu W, Fang X. Self-Assembling Myristoylated Human α-Defensin 5 as a Next-Generation Nanobiotics Potentiates Therapeutic Efficacy in Bacterial Infection. ACS NANO 2018; 12:5284-5296. [PMID: 29856606 DOI: 10.1021/acsnano.7b09109] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The increasing prevalence of antibacterial resistance globally underscores the urgent need to the update of antibiotics. Here, we describe a strategy for inducing the self-assembly of a host-defense antimicrobial peptide (AMP) into nanoparticle antibiotics (termed nanobiotics) with significantly improved pharmacological properties. Our strategy involves the myristoylation of human α-defensin 5 (HD5) as a therapeutic target and subsequent self-assembly in aqueous media in the absence of exogenous excipients. Compared with its parent HD5, the C-terminally myristoylated HD5 (HD5-myr)-assembled nanobiotic exhibited significantly enhanced broad-spectrum bactericidal activity in vitro. Mechanistically, it selectively killed Escherichia coli ( E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) through disruption of the cell wall and/or membrane structure. The in vivo results further demonstrated that the HD5-myr nanobiotic protected against skin infection by MRSA and rescued mice from E. coli-induced sepsis by lowering the systemic bacterial burden and alleviating organ damage. The self-assembled HD5-myr nanobiotic also showed negligible hemolytic activity and substantially low toxicity in animals. Our findings validate this design rationale as a simple yet versatile strategy for generating AMP-derived nanobiotics with excellent in vivo tolerability. This advancement will likely have a broad impact on antibiotic discovery and development efforts aimed at combating antibacterial resistance.
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Affiliation(s)
- Ruyi Lei
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Jinchao Hou
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Qixing Chen
- The Children's Hospital, School of Medicine , Zhejiang University , Hangzhou 310052 , China
| | - Weirong Yuan
- Institute of Human Virology and Department of Biochemistry and Molecular Biology , University of Maryland School of Medicine , Baltimore , Maryland 21201 , United States
| | - Baoli Cheng
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Yaqi Sun
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Yue Jin
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Lujie Ge
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Shmuel A Ben-Sasson
- Department of Developmental Biology, Institute for Medical Research Israel-Canada , The Hebrew University-Hadassah Medical School , Jerusalem 91120 , Israel
| | - Jiong Chen
- Laboratory of Biochemistry and Molecular Biology , Ningbo University , Ningbo 315211 , China
| | - Hangxiang Wang
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology , University of Maryland School of Medicine , Baltimore , Maryland 21201 , United States
| | - Xiangming Fang
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310003 , China
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26
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Zou G, de Leeuw E. Neutralization of Pseudomonas auruginosa Exotoxin A by human neutrophil peptide 1. Biochem Biophys Res Commun 2018; 501:454-457. [PMID: 29738776 DOI: 10.1016/j.bbrc.2018.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 05/02/2018] [Indexed: 01/01/2023]
Abstract
Pseudomonas aeruginosa produces a large number of virulence factors, including the extracellular protein, Exotoxin A (ETA). Human Neutrophil Peptide 1 (HNP1) neutralizes the Exotoxin A. HNP1 belongs to the family of α-defensins, small effector peptides of the innate immune system that combat against microbial infections. Neutralization of bacterial toxins such as ETA by HNP1 is a novel biological function in addition to direct killing of bacteria. In this study, we report on the interaction between HNP-1 and Exotoxin A at the molecular level to allow for the design and development of potent antibacterial peptides as alternatives to classical antibiotics.
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Affiliation(s)
- Guozhang Zou
- U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
| | - Erik de Leeuw
- Institute of Human Virology of the University of Maryland Baltimore School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
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27
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Xu D, Liao C, Zhang B, Tolbert WD, He W, Dai Z, Zhang W, Yuan W, Pazgier M, Liu J, Yu J, Sansonetti PJ, Bevins CL, Shao Y, Lu W. Human Enteric α-Defensin 5 Promotes Shigella Infection by Enhancing Bacterial Adhesion and Invasion. Immunity 2018; 48:1233-1244.e6. [PMID: 29858013 PMCID: PMC6051418 DOI: 10.1016/j.immuni.2018.04.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/18/2018] [Accepted: 04/13/2018] [Indexed: 01/07/2023]
Abstract
Shigella is a Gram-negative bacterium that causes bacillary dysentery worldwide. It invades the intestinal epithelium to elicit intense inflammation and tissue damage, yet the underlying mechanisms of its host selectivity and low infectious inoculum remain perplexing. Here, we report that Shigella co-opts human α-defensin 5 (HD5), a host defense peptide important for intestinal homeostasis and innate immunity, to enhance its adhesion to and invasion of mucosal tissues. HD5 promoted Shigella infection in vitro in a structure-dependent manner. Shigella, commonly devoid of an effective host-adhesion apparatus, preferentially targeted HD5 to augment its ability to colonize the intestinal epithelium through interactions with multiple bacterial membrane proteins. HD5 exacerbated infectivity and Shigella-induced pathology in a culture of human colorectal tissues and three animal models. Our findings illuminate how Shigella exploits innate immunity by turning HD5 into a virulence factor for infection, unveiling a mechanism of action for this highly proficient human pathogen.
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Affiliation(s)
- Dan Xu
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China,Center for Translational Medicine, Frontier Institute of Science and Technology, Xi’an Jiaotong University,Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Chongbing Liao
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China,Center for Translational Medicine, Frontier Institute of Science and Technology, Xi’an Jiaotong University
| | - Bing Zhang
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China
| | - W. David Tolbert
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Wangxiao He
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China,Center for Translational Medicine, Frontier Institute of Science and Technology, Xi’an Jiaotong University,Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Zhijun Dai
- The Second Affiliated Hospital, Xi’an Jiaotong University School of Medicine
| | - Wei Zhang
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Weirong Yuan
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Marzena Pazgier
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Jiankang Liu
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Jun Yu
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, UK
| | | | - Charles L. Bevins
- Department of Microbiology and Immunology, University of California, School of Medicine, Davis, California, USA
| | - Yongping Shao
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China,Center for Translational Medicine, Frontier Institute of Science and Technology, Xi’an Jiaotong University,Correspondence to: (lead contact) or
| | - Wuyuan Lu
- Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China,Center for Translational Medicine, Frontier Institute of Science and Technology, Xi’an Jiaotong University,Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA,Correspondence to: (lead contact) or
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28
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Hoffmann S, Walter S, Blume AK, Fuchs S, Schmidt C, Scholz A, Gerlach RG. High-Throughput Quantification of Bacterial-Cell Interactions Using Virtual Colony Counts. Front Cell Infect Microbiol 2018; 8:43. [PMID: 29497603 PMCID: PMC5818393 DOI: 10.3389/fcimb.2018.00043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/31/2018] [Indexed: 11/13/2022] Open
Abstract
The quantification of bacteria in cell culture infection models is of paramount importance for the characterization of host-pathogen interactions and pathogenicity factors involved. The standard to enumerate bacteria in these assays is plating of a dilution series on solid agar and counting of the resulting colony forming units (CFU). In contrast, the virtual colony count (VCC) method is a high-throughput compatible alternative with minimized manual input. Based on the recording of quantitative growth kinetics, VCC relates the time to reach a given absorbance threshold to the initial cell count using a series of calibration curves. Here, we adapted the VCC method using the model organism Salmonella enterica sv. Typhimurium (S. Typhimurium) in combination with established cell culture-based infection models. For HeLa infections, a direct side-by-side comparison showed a good correlation of VCC with CFU counting after plating. For MDCK cells and RAW macrophages we found that VCC reproduced the expected phenotypes of different S. Typhimurium mutants. Furthermore, we demonstrated the use of VCC to test the inhibition of Salmonella invasion by the probiotic E. coli strain Nissle 1917. Taken together, VCC provides a flexible, label-free, automation-compatible methodology to quantify bacteria in in vitro infection assays.
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Affiliation(s)
| | - Steffi Walter
- Project Group 5, Robert Koch Institute, Wernigerode, Germany
| | - Anne-Kathrin Blume
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Stephan Fuchs
- Division 13: Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
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29
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Raggi L, Bada JL, Lazcano A. On the lack of evolutionary continuity between prebiotic peptides and extant enzymes. Phys Chem Chem Phys 2018; 18:20028-32. [PMID: 27121024 DOI: 10.1039/c6cp00793g] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The significance of experiments that claim to simulate the properties of prebiotic small peptides and polypeptides as models of the polymers that may have preceded proteins is critically addressed. As discussed here, most of these experiments are based only on a small number of a larger set of amino acids that may have been present in the prebiotic environment, supported by both experimental simulations and the repertoire of organic compounds reported in carbonaceous chondrites. Model experiments with small peptides may offer some insights into the processes that contributed to generate the chemical environment leading to the emergence of informational oligomers, but not to the origin of proteins. The large body of circumstantial evidence indicating that catalytic RNA played a key role in the origin of protein synthesis during the early stages of cellular evolution implies that the emergence of the genetic code and of protein biosynthesis are no longer synonymous with the origin of life. Hence, reports on the abiotic synthesis of small catalytic peptides under potential prebiotic conditions do not provide information on the origin of triplet encoded protein biosynthesis, but in some cases may serve as models to understand the properties of the earliest proteins.
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Affiliation(s)
- Luciana Raggi
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-407, Cd. Universitaria, 04510 Ciudad de México, Mexico.
| | - Jeffrey L Bada
- Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0212, USA
| | - Antonio Lazcano
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-407, Cd. Universitaria, 04510 Ciudad de México, Mexico.
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30
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A Simplified Derivative of Human Defensin 5 with Potent and Efficient Activity against Multidrug-Resistant Acinetobacter baumannii. Antimicrob Agents Chemother 2018; 62:AAC.01504-17. [PMID: 29158275 DOI: 10.1128/aac.01504-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 11/04/2017] [Indexed: 02/08/2023] Open
Abstract
The increasing incidence of multidrug-resistant Acinetobacter baumannii (MDRAb) infections worldwide has necessitated the development of novel antibiotics. Human defensin 5 (HD5) is an endogenous peptide with a complex architecture and antibacterial activity against MDRAb In the present study, we attempted to simplify the structure of HD5 by removing disulfide bonds. We found that the Cys2-4 bond was most indispensable for HD5 to inactivate MDRAb, although the antibacterial activity of the derivative was significantly attenuated. We then replaced the noncationic and nonhydrophobic residues with electropositive Arg to increase the antibacterial activity of HD5 derivative that contains a Cys2-4 bond, obtaining another derivative termed HD5d5. The in vitro antibacterial assay and irradiation-wound-infection animal experiment both showed that HD5d5 was much more effective than HD5 at eliminating MDRAb Further investigations revealed that HD5d5 efficiently bound to outer membrane lipid A and penetrated membranes, leading to bacterial collapse and peptide translocation. Compared to HD5, more HD5d5 molecules were located in the cytoplasm of MDRAb, and HD5d5 was more efficient at reducing the activities of superoxide dismutase and catalase, causing the accumulation of reactive oxygen species that are detrimental to microbes. In addition, HD5 failed to suppress the pathogenic outer membrane protein A of Acinetobacter baumannii (AbOmpA) at concentrations up to 50 μg/ml, whereas HD5d5 strongly bound to AbOmpA and exhibited a dramatic toxin-neutralizing ability, thus expanding the repertoire of drugs that is available to treat MDRAb infections.
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31
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Kudryashova E, Seveau SM, Kudryashov DS. Targeting and inactivation of bacterial toxins by human defensins. Biol Chem 2017; 398:1069-1085. [PMID: 28593905 DOI: 10.1515/hsz-2017-0106] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/18/2017] [Indexed: 11/15/2022]
Abstract
Defensins, as a prominent family of antimicrobial peptides (AMP), are major effectors of the innate immunity with a broad range of immune modulatory and antimicrobial activities. In particular, defensins are the only recognized fast-response molecules that can neutralize a broad range of bacterial toxins, many of which are among the deadliest compounds on the planet. For a decade, the mystery of how a small and structurally conserved group of peptides can neutralize a heterogeneous group of toxins with little to no sequential and structural similarity remained unresolved. Recently, it was found that defensins recognize and target structural plasticity/thermodynamic instability, fundamental physicochemical properties that unite many bacterial toxins and distinguish them from the majority of host proteins. Binding of human defensins promotes local unfolding of the affected toxins, destabilizes their secondary and tertiary structures, increases susceptibility to proteolysis, and leads to their precipitation. While the details of toxin destabilization by defensins remain obscure, here we briefly review properties and activities of bacterial toxins known to be affected by or resilient to defensins, and discuss how recognized features of defensins correlate with the observed inactivation.
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32
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Valere K, Lu W, Chang TL. Key Determinants of Human α-Defensin 5 and 6 for Enhancement of HIV Infectivity. Viruses 2017; 9:E244. [PMID: 28850095 PMCID: PMC5618010 DOI: 10.3390/v9090244] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/13/2017] [Accepted: 08/24/2017] [Indexed: 12/22/2022] Open
Abstract
Defensins are antimicrobial peptides important for mucosal innate immunity. They exhibit a broad spectrum of activity against bacteria, viruses, and fungi. Levels of α-defensins are elevated at the genital mucosa of individuals with sexually transmitted infections (STIs). Somewhat paradoxically, human α-defensin 5 and 6 (HD5 and HD6) promote human immunodeficiency virus (HIV) infectivity, and contribute to STI-mediated enhancement of HIV infection in vitro. Specific amino acid residues of HD5 and HD6 that are crucial for antimicrobial activities have been characterized previously; however, the key determinants of defensins responsible for enhancement of HIV infectivity are not known. Here, we have identified residues of HD5 and HD6 that are required for enhancement of HIV attachment and infection. Most of these residues are involved in hydrophobicity and self-association of defensins. Specifically, we found that mutant defensins L16A-HD5, E21me-HD5, L26A-HD5, Y27A-HD5, F2A-HD6, H27W-HD6, and F29A-HD6 significantly lost their ability to promote HIV attachment and infection. L29A mutation also reduced HIV infection-enhancing activity of HD5. Additionally, a number of mutations in charged residues variably affected the profile of HIV attachment and infectivity. One HD5 charged mutation, R28A, notably resulted in a 34-48% loss of enhanced HIV infectivity and attachment. These results indicate that defensin determinants that maintain high-ordered amphipathic structure are crucial for HIV enhancing activity. In a comparative analysis of the mutant defensins, we found that for some defensin mutants enhancement of HIV infectivity was associated with the reverse transcription step, suggesting a novel, HIV attachment-independent, mechanism of defensin-mediated HIV enhancement.
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Affiliation(s)
- Kimyata Valere
- Department of Microbiology and Molecular Genetics, Rutgers University, New Jersey Medical School, Newark, NJ 07103, USA.
| | - Wuyuan Lu
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21250, USA.
| | - Theresa L Chang
- Department of Microbiology and Molecular Genetics, Rutgers University, New Jersey Medical School, Newark, NJ 07103, USA.
- Public Health Research Institute, Rutgers University, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103, USA.
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33
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Sankaran-Walters S, Hart R, Dills C. Guardians of the Gut: Enteric Defensins. Front Microbiol 2017; 8:647. [PMID: 28469609 PMCID: PMC5395650 DOI: 10.3389/fmicb.2017.00647] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/29/2017] [Indexed: 01/01/2023] Open
Abstract
Enteric defensins likely play a key role in the management of the human microbiome throughout development. The functional and mechanistic diversity of defensins is much greater than was initially thought. Defensin expression and overall Paneth cell physiology likely plays a key role in the development of colitis and other inflammatory or dysbiotic diseases of the gut. As our understanding of enteric defensins grows, their potential as tools of clinical intervention becomes more apparent. In this review, we focus on the function and activity of Paneth Cell defensins and highlight their role in disease.
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34
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Mathew B, Nagaraj R. Variations in the interaction of human defensins with Escherichia coli: Possible implications in bacterial killing. PLoS One 2017; 12:e0175858. [PMID: 28423004 PMCID: PMC5397029 DOI: 10.1371/journal.pone.0175858] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/31/2017] [Indexed: 01/08/2023] Open
Abstract
Human α and β-defensins are cationic antimicrobial peptides characterized by three disulfide bonds with a triple stranded β-sheet motif. It is presumed that interaction with the bacterial cell surface and membrane permeabilization by defensins is an important step in the killing process. In this study, we have compared interactions of three human α-defensins HNP3, HNP4, HD5 and human β-defensins HBD1-4 that are active against Escherichia coli, with its cell surface and inner membrane as well as negatively charged model membranes. We have also included the inactive α-defensin HD6 in the study. Among the α-defensins, HNP4, HD5 and HD6 were more effective in increasing the zeta potential as compared to HNP3. Among the β-defensins, HBD1 was the least effective in increasing the zeta potential. The zeta potential modulation data indicate variations in the surface charge neutralizing ability of α- and β-defensins. Comparison of E. coli inner membrane and model membrane permeabilizing abilities indicated that HD5, HD6 and HBD1 do not permeabilize membranes. Although HBD4 does not permeabilize model membranes, considerable damage to the inner membrane of E. coli is observed. Our data indicate that mammalian defensins do not kill E. coli by a simple mechanism involving membrane permeabilization though their antibacterial potencies are very similar.
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Affiliation(s)
- Basil Mathew
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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35
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Min HJ, Yun H, Ji S, Rajasekaran G, Kim JI, Kim JS, Shin SY, Lee CW. Rattusin structure reveals a novel defensin scaffold formed by intermolecular disulfide exchanges. Sci Rep 2017; 7:45282. [PMID: 28345637 PMCID: PMC5366907 DOI: 10.1038/srep45282] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 02/23/2017] [Indexed: 12/14/2022] Open
Abstract
Defensin peptides are essential for innate immunity in humans and other living systems, as they provide protection against infectious pathogens and regulate the immune response. Here, we report the solution structure of rattusin (RTSN), an α-defensin-related peptide, which revealed a novel C2-symmetric disulfide-linked dimeric structure. RTSN was synthesized by solid-phase peptide synthesis (SPPS) and refolded by air oxidation in vitro. Dimerization of the refolded RTSN (r-RTSN) resulted from five intermolecular disulfide (SS) bond exchanges formed by ten cysteines within two protomer chains. The SS bond pairings of r-RTSN were determined by mass analysis of peptide fragments cleaved by trypsin digestion. In addition to mass analysis, nuclear magnetic resonance (NMR) experiments for a C15S mutant and r-RTSN confirmed that the intermolecular SS bond structure of r-RTSN showed an I-V', II-IV', III-III', IV-II', V-I' arrangement. The overall structure of r-RTSN exhibited a cylindrical array, similar to that of β-sandwich folds, with a highly basic surface. Furthermore, fluorescence spectroscopy results suggest that r-RTSN exerts bactericidal activity by damaging membrane integrity. Collectively, these results provide a novel structural scaffold for designing highly potent peptide-based antibiotics suitable for use under various physiological conditions.
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Affiliation(s)
- Hye Jung Min
- Department of Chemistry, Chonnam National University, Gwangju 61186, South Korea.,Department of Pharmaceutical Cosmetics, Kwangju Women's University, Gwangju 62396, South Korea
| | - Hyosuk Yun
- Department of Chemistry, Chonnam National University, Gwangju 61186, South Korea
| | - Sehyeon Ji
- Department of Chemistry, Chonnam National University, Gwangju 61186, South Korea
| | - Ganesan Rajasekaran
- Department of Medical Science, Graduate School and Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, Gwangju 61452, South Korea
| | - Jae Il Kim
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 61005, South Korea
| | - Jeong-Sun Kim
- Department of Chemistry, Chonnam National University, Gwangju 61186, South Korea
| | - Song Yub Shin
- Department of Medical Science, Graduate School and Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, Gwangju 61452, South Korea
| | - Chul Won Lee
- Department of Chemistry, Chonnam National University, Gwangju 61186, South Korea
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36
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Porto WF, Nolasco DO, Pires ÁS, Pereira RW, Franco OL, Alencar SA. Prediction of the impact of coding missense and nonsense single nucleotide polymorphisms on HD5 and HBD1 antibacterial activity against Escherichia coli. Biopolymers 2017; 106:633-44. [PMID: 27160989 DOI: 10.1002/bip.22866] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/14/2016] [Accepted: 04/26/2016] [Indexed: 01/01/2023]
Abstract
Defensins confer host defense against microorganisms and are important for human health. Single nucleotide polymorphisms (SNPs) in defensin gene-coding regions could lead to less active variants. Using SNP data available at the dbSNP database and frequency information from the 1000 Genomes Project, two DEFA5 (L26I and R13H) and eight DEFB1 (C35S, K31T, K33R, R29G, V06I, C12Y, Y28* and C05*) missense and nonsense SNPs that are located within mature regions of the coded defensins were retrieved. Such SNPs are rare and population restricted. In order to assess their antibacterial activity against Escherichia coli, two linear regression models were used from a previous work, which models the antibacterial activity as a function of solvation potential energy, using molecular dynamics data. Regarding only the antibacterial predictions, for HD5, no biological differences between wild-type and its variants were observed; while for HBD1, the results suggest that the R29G, K31T, Y28* and C05* variants could be less active than the wild-type one. The data here reported could lead to a substantial improvement in knowledge about the impact of missense SNPs in human defensins and their world distribution. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 633-644, 2016.
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Affiliation(s)
- William F Porto
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil.,Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil
| | - Diego O Nolasco
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA
| | - Állan S Pires
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil.,Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil
| | - Rinaldo W Pereira
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil
| | - Octávio L Franco
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil. .,Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil. .,S-Inova Biotech, Pos-Graduação Em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, MS, Brazil.
| | - Sérgio A Alencar
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia, Universidade Católica De Brasília, Brasília, DF, Brazil
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37
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Montero-Alejo V, Corzo G, Porro-Suardíaz J, Pardo-Ruiz Z, Perera E, Rodríguez-Viera L, Sánchez-Díaz G, Hernández-Rodríguez EW, Álvarez C, Peigneur S, Tytgat J, Perdomo-Morales R. Panusin represents a new family of β-defensin-like peptides in invertebrates. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 67:310-321. [PMID: 27616720 DOI: 10.1016/j.dci.2016.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 06/06/2023]
Abstract
Beta_defensin have been solely found in vertebrates until β-defensin-like peptides were described as transcript isoforms in two species of Panulirus genus. They were considered as putative antimicrobials since their biological activity have not been demonstrated. Here we purified and characterized a defensin-like peptide from the hemocytes of spiny lobster P. argus, hereafter named panusin. Structurally, panusin presents a cysteine-stabilized α/β motif, and is prone to form homodimers. Biological activity of panusin showed broad-spectrum antimicrobial activity, characterized for being strikingly salt-resistant. Panusin did not showed hemolytic activity but was demonstrated its binding capacity to different lipid membrane models, indicating amphipathicity of β-sheet core as driving force for its antimicrobial activity. Panusin is considered a new kind of arthropod defensin which share structural and biological features with beta-defensin from vertebrates. The presence of beta-defensin like peptides in crustacean might suggest the emergence of the evolutionary relationship of β-defensins from vertebrates.
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Affiliation(s)
- Vivian Montero-Alejo
- Biochemistry Department, Center for Pharmaceuticals Research and Development, Havana, Cuba.
| | - Gerardo Corzo
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Mexico
| | - Javier Porro-Suardíaz
- Biochemistry Department, Center for Pharmaceuticals Research and Development, Havana, Cuba
| | - Zenia Pardo-Ruiz
- Biochemistry Department, Center for Pharmaceuticals Research and Development, Havana, Cuba
| | - Erick Perera
- Department of Fish Physiology and Biotechnology, Institute of Aquaculture Torre de la Sal (IATS-CSIC), Castellón, Spain
| | | | - Gabriela Sánchez-Díaz
- Department for Basic and Biomedical Sciences, Medicine Faculty, Artemisa, Cuba; Laboratory of Computational and Theoretical Chemistry, University of Havana, Havana, Cuba
| | - Erix Wiliam Hernández-Rodríguez
- Department for Basic and Biomedical Sciences, Medicine Faculty, Artemisa, Cuba; Laboratory of Computational and Theoretical Chemistry, University of Havana, Havana, Cuba
| | - Carlos Álvarez
- Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
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Chairatana P, Nolan EM. Defensins, lectins, mucins, and secretory immunoglobulin A: microbe-binding biomolecules that contribute to mucosal immunity in the human gut. Crit Rev Biochem Mol Biol 2017; 52:45-56. [PMID: 27841019 PMCID: PMC5233583 DOI: 10.1080/10409238.2016.1243654] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/19/2016] [Accepted: 09/28/2016] [Indexed: 02/08/2023]
Abstract
In the intestine, the mucosal immune system plays essential roles in maintaining homeostasis between the host and microorganisms, and protecting the host from pathogenic invaders. Epithelial cells produce and release a variety of biomolecules into the mucosa and lumen that contribute to immunity. In this review, we focus on a subset of these remarkable host-defense factors - enteric α-defensins, select lectins, mucins, and secretory immunoglobulin A - that have the capacity to bind microbes and thereby contribute to barrier function in the human gut. We provide an overview of the intestinal epithelium, describe specialized secretory cells named Paneth cells, and summarize our current understanding of the biophysical and functional properties of these select microbe-binding biomolecules. We intend for this compilation to complement prior reviews on intestinal host-defense factors, highlight recent advances in the field, and motivate investigations that further illuminate molecular mechanisms as well as the interplay between these molecules and microbes.
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Affiliation(s)
- Phoom Chairatana
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Elizabeth M. Nolan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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39
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Long ZZ, Nie QH. Paneth cells, antimicrobial peptides, and intestinal mucosal immunity. Shijie Huaren Xiaohua Zazhi 2017; 25:209-219. [DOI: 10.11569/wcjd.v25.i3.209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Paneth cells (PCs) and their antimicrobial peptides (AMPs) are closely related to the ecological unbalance of gut microbiota, intestinal inflammation, and systemic infections. The dysfunction of intestinal mucosal barrier and innate immunity is always accompanied with changes in the levels of AMPs, for example, alpha-defensins and other inflammatory mediators produced by PCs. Studies show that PCs can alter their functional status and release effector molecules under some conditions such as cholinergic agonists, microorganisms and their antigens, enteral nutrition, and genetic susceptibility. Therefore, these conditions can induce inflammatory bowel disease, bacterial translocation, overgrowth of gut microbe, and damage to immune tolerance. The research on PCs can provide new targets and strategies for clinical treatment of the relevant diseases. In this paper, we discuss the relationship of PCs and their AMPs with intestinal mucosal barrier and innate immunity.
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α-Defensin HD5 Inhibits Human Papillomavirus 16 Infection via Capsid Stabilization and Redirection to the Lysosome. mBio 2017; 8:mBio.02304-16. [PMID: 28119475 PMCID: PMC5263252 DOI: 10.1128/mbio.02304-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
α-Defensins are an important class of abundant innate immune effectors that are potently antiviral against a number of nonenveloped viral pathogens; however, a common mechanism to explain their ability to block infection by these unrelated viruses is lacking. We previously found that human defensin 5 (HD5) blocks a critical host-mediated proteolytic processing step required for human papillomavirus (HPV) infection. Here, we show that bypassing the requirement for this cleavage failed to abrogate HD5 inhibition. Instead, HD5 altered HPV trafficking in the cell. In the presence of an inhibitory concentration of HD5, HPV was internalized and reached the early endosome. The internalized capsid became permeable to antibodies and proteases; however, HD5 prevented dissociation of the viral capsid from the genome, reduced viral trafficking to the trans-Golgi network, redirected the incoming viral particle to the lysosome, and accelerated the degradation of internalized capsid proteins. This mechanism is equivalent to the mechanism by which HD5 inhibits human adenovirus. Thus, our data support capsid stabilization and redirection to the lysosome during infection as a general antiviral mechanism of α-defensins against nonenveloped viruses. IMPORTANCE Although the antiviral activity of α-defensins against enveloped viruses can be largely explained by interference with receptor binding and fusion, a common mechanism for inhibition of nonenveloped viruses remains elusive. In studies of a prominent human α-defensin that is expressed in the gut and in the male and female genitourinary tract, we discovered striking parallels between the mechanisms of inhibition of HPV and human adenovirus infection. Thus, detailed studies of the impact of α-defensins on the intracellular trafficking of two disparate viruses support a general mechanism of α-defensin antiviral activity against nonenveloped viruses.
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41
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Chairatana P, Nolan EM. Defensins, lectins, mucins, and secretory immunoglobulin A: microbe-binding biomolecules that contribute to mucosal immunity in the human gut. Crit Rev Biochem Mol Biol 2016. [PMID: 27841019 DOI: 10,1080/10409238.2016.124365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the intestine, the mucosal immune system plays essential roles in maintaining homeostasis between the host and microorganisms, and protecting the host from pathogenic invaders. Epithelial cells produce and release a variety of biomolecules into the mucosa and lumen that contribute to immunity. In this review, we focus on a subset of these remarkable host-defense factors - enteric α-defensins, select lectins, mucins, and secretory immunoglobulin A - that have the capacity to bind microbes and thereby contribute to barrier function in the human gut. We provide an overview of the intestinal epithelium, describe specialized secretory cells named Paneth cells, and summarize our current understanding of the biophysical and functional properties of these select microbe-binding biomolecules. We intend for this compilation to complement prior reviews on intestinal host-defense factors, highlight recent advances in the field, and motivate investigations that further illuminate molecular mechanisms as well as the interplay between these molecules and microbes.
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Affiliation(s)
- Phoom Chairatana
- a Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Elizabeth M Nolan
- a Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA , USA
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42
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Thermodynamic instability of viral proteins is a pathogen-associated molecular pattern targeted by human defensins. Sci Rep 2016; 6:32499. [PMID: 27581352 PMCID: PMC5007486 DOI: 10.1038/srep32499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 08/08/2016] [Indexed: 11/21/2022] Open
Abstract
Human defensins are innate immune defense peptides with a remarkably broad repertoire of anti-pathogen activities. In addition to modulating immune response, inflammation, and angiogenesis, disintegrating bacterial membranes, and inactivating bacterial toxins, defensins are known to intercept various viruses at different stages of their life cycles, while remaining relatively benign towards human cells and proteins. Recently we have found that human defensins inactivate proteinaceous bacterial toxins by taking advantage of their low thermodynamic stability and acting as natural “anti-chaperones”, i.e. destabilizing the native conformation of the toxins. In the present study we tested various proteins produced by several viruses (HIV-1, PFV, and TEV) and found them to be susceptible to destabilizing effects of human α-defensins HNP-1 and HD-5 and the synthetic θ-defensin RC-101, but not β-defensins hBD-1 and hBD-2 or structurally related plant-derived peptides. Defensin-induced unfolding promoted exposure of hydrophobic groups otherwise confined to the core of the viral proteins. This resulted in precipitation, an enhanced susceptibility to proteolytic cleavage, and a loss of viral protein activities. We propose, that defensins recognize and target a common and essential physico-chemical property shared by many bacterial toxins and viral proteins – the intrinsically low thermodynamic protein stability.
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Porto WF, Nolasco DO, Pires ÁS, Fernandes GR, Franco OL, Alencar SA. HD5 and HBD1 variants’ solvation potential energy correlates with their antibacterial activity against Escherichia coli. Biopolymers 2016; 106:43-50. [DOI: 10.1002/bip.22763] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 10/22/2015] [Accepted: 11/02/2015] [Indexed: 11/06/2022]
Affiliation(s)
- William F. Porto
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
- Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
| | - Diego O. Nolasco
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
- Curso De Física; Universidade Católica De Brasília; Brasília DF Brazil
| | - Állan S. Pires
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
- Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
| | - Gabriel R. Fernandes
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
| | - Octávio L. Franco
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
- Centro De Análises Proteômicas E Bioquímicas, Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
- S-Inova Biotech; Pos Graduação em Biotecnologia; Universidade Catolica Dom Bosco; Campo Grande Campo Grande Brazil
| | - Sérgio A. Alencar
- Programa De Pós-Graduação Em Ciências Genômicas E Biotecnologia; Universidade Católica De Brasília; Brasília- DF Brazil
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Mathew B, Nagaraj R. Antimicrobial activity of human α-defensin 6 analogs: insights into the physico-chemical reasons behind weak bactericidal activity of HD6 in vitro. J Pept Sci 2015; 21:811-8. [PMID: 26400692 DOI: 10.1002/psc.2821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/29/2015] [Accepted: 08/19/2015] [Indexed: 01/07/2023]
Abstract
Human α-defensin 6 (HD6), unlike other mammalian defensins, does not exhibit bactericidal activity, particularly against aerobic bacteria. Monomeric HD6 has a tertiary structure similar to other α-defensins in the crystalline state. However, the physico-chemical reasons behind the lack of antibacterial activity of HD6 are yet to be established unequivocally. In this study, we have investigated the antimicrobial activity of HD6 analogs. A linear analog of HD6, in which the distribution of arginine residues was similar to active α-defensins, shows broad-spectrum antimicrobial activity, indicating that atypical distribution of arginine residues contributes to the inactivity of HD6. Peptides spanning the N-terminal cationic segment were active against a wide range of organisms. Antimicrobial potency of these shorter analogs was further enhanced when myristic acid was conjugated at the N-terminus. Cytoplasmic localization of the analogs without fatty acylation was observed to be necessary for bacterial killing, while they exhibited fungicidal activity by permeabilizing Candida albicans membranes. Myristoylated analogs and the linear full-length arginine analog exhibited activity by permeabilizing bacterial and fungal membranes. Our study provides insights into the lack of bactericidal activity of HD6 against aerobic bacteria.
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Affiliation(s)
- Basil Mathew
- CSIR - Centre for Cellular and Molecular Biology, Hyderabad, 500 007, India
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45
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Mathew B, Nagaraj R. Antimicrobial activity of human α-defensin 5 and its linear analogs: N-terminal fatty acylation results in enhanced antimicrobial activity of the linear analogs. Peptides 2015. [PMID: 26206286 DOI: 10.1016/j.peptides.2015.07.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Human α-defensin 5 (HD5) exhibits broad spectrum antimicrobial activity and plays an important role in mucosal immunity of the small intestine. Although there have been several studies, the structural requirements for activity and mechanism of bacterial killing is yet to be established unequivocally. In this study, we have investigated the antimicrobial activity of HD5 and linear analogs. Cysteine deletions attenuated the antibacterial activity considerably. Candidacidal activity was affected to a lesser extent. Fatty acid conjugated linear analogs showed antimicrobial activity comparable activity to HD5. Effective surface charge neutralization of bacteria was observed for HD5 as compared to the non-fatty acylated linear analogs. Our results show that HD5 and non-fatty acylated linear analogs enter the bacterial cytoplasm without causing damage to the bacterial inner membrane. Although fatty acylated peptides exhibited antimicrobial activity comparable to HD5, their mechanism of action involved permeabilization of the Escherichia coli inner membrane. HD5 and analogs had the ability to bind plasmid DNA. HD5 had greater binding affinity to plasmid DNA as compared to the analogs. The three dimensional structure of HD5 favors greater interaction with the bacterial cell surface and also with DNA. Antibacterial activity of HD5 involves entry into bacterial cytoplasm and binding to DNA which would result in shut down of the bacterial metabolism leading to cell death. We show how a moderately active linear peptide derived from the α-defensin HD5 can be engineered to enhance antimicrobial activity almost comparable to the native peptide.
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Affiliation(s)
- Basil Mathew
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Ramakrishnan Nagaraj
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
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46
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Snijder J, van de Waterbeemd M, Glover MS, Shi L, Clemmer DE, Heck AJR. Conformational landscape and pathway of disulfide bond reduction of human alpha defensin. Protein Sci 2015; 24:1264-71. [PMID: 25970658 DOI: 10.1002/pro.2694] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/30/2015] [Accepted: 04/01/2015] [Indexed: 12/30/2022]
Abstract
Human alpha defensins are a class of antimicrobial peptides with additional antiviral activity. Such antimicrobial peptides constitute a major part of mammalian innate immunity. Alpha defensins contain six cysteines, which form three well defined disulfide bridges under oxidizing conditions. Residues C3-C31, C5-C20, and C10-C30 form disulfide pairs in the native structure of the peptide. The major tissue in which HD5 is expressed is the crypt of the small intestine, an anaerobic niche that should allow for substantial pools of both oxidized and (partly) reduced HD5. We used ion mobility coupled to mass spectrometry to track the structural changes in HD5 upon disulfide bond reduction. We found evidence of stepwise unfolding of HD5 with sequential reduction of the three disulfide bonds. Alkylation of free cysteines followed by tandem mass spectrometry of the corresponding partially reduced states revealed a dominant pathway of reductive unfolding. The majority of HD5 unfolds by initial reduction of C5-C20, followed by C10-C30 and C3-C31. We find additional evidence for a minor pathway that starts with reduction of C3-C31, followed by C5-C20 and C10-C30. Our results provide insight into the pathway and conformational landscape of disulfide bond reduction in HD5.
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Affiliation(s)
- Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584, CH Utrecht, The Netherlands.,Netherlands Proteomics Centre, 3584, CH Utrecht, The Netherlands
| | - Michiel van de Waterbeemd
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584, CH Utrecht, The Netherlands.,Netherlands Proteomics Centre, 3584, CH Utrecht, The Netherlands
| | - Matthew S Glover
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - Liuqing Shi
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - David E Clemmer
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584, CH Utrecht, The Netherlands.,Netherlands Proteomics Centre, 3584, CH Utrecht, The Netherlands
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47
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Wang C, Shen M, Gohain N, Tolbert WD, Chen F, Zhang N, Yang K, Wang A, Su Y, Cheng T, Zhao J, Pazgier M, Wang J. Design of a potent antibiotic peptide based on the active region of human defensin 5. J Med Chem 2015; 58:3083-93. [PMID: 25782105 DOI: 10.1021/jm501824a] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Human defensin 5 (HD5) is a broad-spectrum antibacterial peptide with a C-terminal active region. To promote the development of this peptide into an antibiotic, we initially substituted Glu21 with Arg because it is an electronegative residue located around the active region. Although detrimental to dimer formation, the E21R substitution markedly enhanced the antibacterial activity of HD5 and increased its ability to penetrate cell membranes, demonstrating that increasing the electropositive charge compensated for the effect of dimer disruption. Subsequently, a partial Arg scanning mutagenesis was performed, and Thr7 was selected for replacement with Arg to further strengthen the antibacterial activity. The newly designed peptide, T7E21R-HD5, exhibited potent antibacterial activity, even in saline and serum solutions. In contrast to monomeric E21R-HD5, T7E21R-HD5 assembled into an atypical dimer with parallel β strands, thus expanding the role of increasing electropositive charge in bactericidal activity and providing a useful guide for further defensin-derived antibiotic design.
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Affiliation(s)
- Cheng Wang
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Mingqiang Shen
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Neelakshi Gohain
- ‡Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - William D Tolbert
- ‡Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Fang Chen
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Naixin Zhang
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Ke Yang
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China.,§Department of Nephrology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Aiping Wang
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Yongping Su
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Tianmin Cheng
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
| | - Jinghong Zhao
- §Department of Nephrology, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, China
| | - Marzena Pazgier
- ‡Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Junping Wang
- †State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, 400038, China
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48
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Chileveru HR, Lim SA, Chairatana P, Wommack AJ, Chiang IL, Nolan EM. Visualizing attack of Escherichia coli by the antimicrobial peptide human defensin 5. Biochemistry 2015; 54:1767-77. [PMID: 25664683 DOI: 10.1021/bi501483q] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Human α-defensin 5 (HD5) is a 32-residue cysteine-rich host-defense peptide that exhibits broad-spectrum antimicrobial activity and contributes to innate immunity in the human gut and other organ systems. Despite many years of investigation, its antimicrobial mechanism of action remains unclear. In this work, we report that HD5ox, the oxidized form of this peptide that exhibits three regiospecific disulfide bonds, causes distinct morphological changes to Escherichia coli and other Gram-negative microbes. These morphologies include bleb formation, cellular elongation, and clumping. The blebs are up to ∼1 μm wide and typically form at the site of cell division or cell poles. Studies with E. coli expressing cytoplasmic GFP reveal that HD5ox treatment causes GFP emission to localize in the bleb. To probe the cellular uptake of HD5ox and subsequent localization, we describe the design and characterization of a fluorophore-HD5 conjugate family. By employing these peptides, we demonstrate that fluorophore-HD5ox conjugates harboring the rhodamine and coumarin fluorophores enter the E. coli cytoplasm. On the basis of the fluorescence profiles, each of these fluorophore-HD5ox conjugates localizes to the site of cell division and cell poles. These studies support the notion that HD5ox, at least in part, exerts its antibacterial activity against E. coli and other Gram-negative microbes in the cytoplasm.
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Affiliation(s)
- Haritha R Chileveru
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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49
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Ericksen B. Quantification of polysaccharides fixed to Gram stained slides using lactophenol cotton blue and digital image processing. F1000Res 2015; 4:1. [PMID: 29333228 PMCID: PMC5754746 DOI: 10.12688/f1000research.5779.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/04/2017] [Indexed: 01/10/2023] Open
Abstract
Dark blue rings and circles emerged when the non-specific polysaccharide stain lactophenol cotton blue was added to Gram stained slides. The dark blue staining is attributable to the presence of capsular polysaccharides and bacterial slime associated with clumps of Gram-negative bacteria. Since all bacterial cells are glycosylated and concentrate polysaccharides from the media, the majority of cells stain light blue. The contrast between dark and light staining is sufficient to enable a digital image processing thresholding technique to be quantitative with little background noise. Prior to the addition of lactophenol cotton blue, the Gram-stained slides appeared unremarkable, lacking ubiquitous clumps or stained polysaccharides. Adding lactophenol cotton blue to Gram stained slides is a quick and inexpensive way to screen cell cultures for bacterial slime, clumps and biofilms that are invisible using the Gram stain alone.
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Affiliation(s)
- Bryan Ericksen
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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50
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New role for human α-defensin 5 in the fight against hypervirulent Clostridium difficile strains. Infect Immun 2014; 83:986-95. [PMID: 25547793 DOI: 10.1128/iai.02955-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Clostridium difficile infection (CDI), one of the most common hospital-acquired infections, is increasing in incidence and severity with the emergence and diffusion of hypervirulent strains. CDI is precipitated by antibiotic treatment that destroys the equilibrium of the gut microbiota. Human α-defensin 5 (HD5), the most abundant enteric antimicrobial peptide, is a key regulator of gut microbiota homeostasis, yet it is still unknown if C. difficile, which successfully evades killing by other host microbicidal peptides, is susceptible to HD5. We evaluated, by means of viability assay, fluorescence-activated cell sorter (FACS) analysis, and electron microscopy, the antimicrobial activities of α-defensins 1 and 5 against a panel of C. difficile strains encompassing the most prevalent epidemic and hypervirulent PCR ribotypes in Europe (012, 014/020, 106, 018, 027, and 078). Here we show that (i) concentrations of HD5 within the intestinal physiological range produced massive C. difficile cell killing; (ii) HD5 bactericidal activity was mediated by membrane depolarization and bacterial fragmentation with a pattern of damage peculiar to C. difficile bacilli, compared to commensals like Escherichia coli and Enterococcus faecalis; and (iii) unexpectedly, hypervirulent ribotypes were among the most susceptible to both defensins. These results support the notion that HD5, naturally present at very high concentrations in the mucosa of the small intestine, could indeed control the very early steps of CDI by killing C. difficile bacilli at their germination site. As a consequence, HD5 can be regarded as a good candidate for the containment of hypervirulent C. difficile strains, and it could be exploited in the therapy of CDI and relapsing C. difficile-associated disease.
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