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Juba M, Porter D, Dean S, Gillmor S, Bishop B. Characterization and performance of short cationic antimicrobial peptide isomers. Biopolymers 2016; 100:387-401. [PMID: 23532931 DOI: 10.1002/bip.22244] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/01/2013] [Accepted: 02/11/2013] [Indexed: 02/03/2023]
Abstract
Cationic antimicrobial peptides (CAMPs) represent an ancient defense mechanism against invading bacteria, with peptides such as the cathelicidins being essential elements of vertebrate innate immunity. CAMPs are typically associated with broad-spectrum antimicrobial potency and limited bacterial resistance. The cathelicidin identified from the elapid snake Naja atra (NA-CATH) contains a semi-conserved repeated 11-residue motif (ATRA motif) with a sequence pattern consistent with formation of an amphipathic helical conformation. Short peptide amides (ATRA-1, -1A, -1P, and -2) generated based on the pair of ATRA motifs in NA-CATH exhibited varied antimicrobial potencies. The small size of the ATRA peptides, coupled with their varied antimicrobial performances, make them interesting models to study the impact various physico-chemical properties have on antimicrobial performance in helical CAMPs. Accordingly, the D- and L-enantiomers of the peptide ATRA-1A, which in earlier studies had shown both good antimicrobial performance and strong helical character, were investigated in order to assess the impact peptide stereochemistry has on antimicrobial performance and interaction with chiral membranes. The ATRA-1A isomers exhibit varied potencies against four bacterial strains, and their conformational properties in the presence of mixed zwitterionic/anionic liposomes are influenced by anionic lipid content. These studies reveal subtle differences in the properties of the peptide isomers. Differences are also seen in the abilities of the ATRA-1A isomers to induce liposome fusion/aggregation, bilayer rearrangement and lysing through turbidity studies and fluorescence microscopy. The similarities and differences in the properties of the ATRA-1A isomers could aid in efforts to develop D-peptide-based therapeutics using high-performing L-peptides as templates.
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Affiliation(s)
- Melanie Juba
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA
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Kessler MS, Samuel RL, Gillmor SD. Polka-dotted vesicles: lipid bilayer dynamics and cross-linking effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2982-2991. [PMID: 23360253 DOI: 10.1021/la3042007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have investigated the effects of cross-linking perturbations on lipid phase-domain coalescence. Our model system explores cross-linking in the fluid-disordered phase of two-phase vesicles. Here, we quantify the vesicle population shift from the expected predominance of two-domain, two-phase configuration to a multidomain vesicle majority. We have found that the increase in multidomain vesicles is a distinct outcome from the cross-linking of biotinylated lipids and avidin. Analysis of our cross-linking data suggests that avidin forms clusters on the surface of the fluid-disordered domains, resulting in a large immobile fraction and restricted diffusion. In cellular membranes, receptor concentrations are similar to our experimental model, and we expect similar cluster formations, leading to nonideal mixing and lateral heterogeneity. We have induced and quantified a global response by cross-linking only a small percentage of lipids in our system, similar to receptor-ligand interactions on the cell membrane. Common activities, such as ligand-receptor coupling, contribute to lateral heterogeneity and membrane protein clustering, adding to cell membrane complexity. Fundamental studies into subtle shifts such as cross-linking events, which induce global cellular response, are pertinent to understanding membrane activities and effects of external stimuli.
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Affiliation(s)
- Michael S Kessler
- Department of Chemistry, 107 Corcoran Hall, George Washington University, 725 21st Street, N.W., Washington, DC 20052, USA
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Fulop T, Le Page A, Garneau H, Azimi N, Baehl S, Dupuis G, Pawelec G, Larbi A. Aging, immunosenescence and membrane rafts: the lipid connection. LONGEVITY & HEALTHSPAN 2012; 1:6. [PMID: 24764511 PMCID: PMC3886260 DOI: 10.1186/2046-2395-1-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 07/13/2012] [Indexed: 11/10/2022]
Abstract
The decreased efficiency of immune responses in older people is partly a consequence of alterations in T lymphocyte functions caused by modifications in the early events of signal transduction. Several alterations in the signaling pathways of T lymphocytes have been described in older humans and animals. A unifying cause could be modifications in the physicochemical properties of the plasma membrane resulting from changes in its lipid composition and the distribution and function of lipid rafts (LR). The latter serve to assemble the initial components of the signaling cascade. Accumulating data suggest that the function of plasma membrane LR is altered with aging; we hypothesize that this would significantly contribute to immune dysregulation. The role of aging and cholesterol in LR functions in T lymphocytes is reviewed and discussed here.
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Affiliation(s)
- Tamas Fulop
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada ; Research Center on Aging, University of Sherbrooke, 1036, rue Belvedere Sud, Sherbrooke, Qc, J1H 4C4, Canada
| | - Aurélie Le Page
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada
| | - Hugo Garneau
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada
| | - Naheed Azimi
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada
| | - Sarra Baehl
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada
| | - Gilles Dupuis
- Department of Biochemistry, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, J1H 5N4, Canada
| | - Graham Pawelec
- Center for Medical Research, Tübingen Aging and Tumor Immunology Group, University of Tübingen, Waldhörnlestrasse 22, Tübingen, D-72072, Germany
| | - Anis Larbi
- Singapore Immunology Network (SIgN), Immunos Building/Biopolis, Agency for Science Technology and Research (ASTAR), 8A Biomedical Grove, Singapore, 138648, Singapore
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Jaqaman K, Grinstein S. Regulation from within: the cytoskeleton in transmembrane signaling. Trends Cell Biol 2012; 22:515-26. [PMID: 22917551 DOI: 10.1016/j.tcb.2012.07.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/17/2012] [Accepted: 07/17/2012] [Indexed: 12/16/2022]
Abstract
There is mounting evidence that the plasma membrane is highly dynamic and organized in a complex manner. The cortical cytoskeleton is proving to be a particularly important regulator of plasmalemmal organization, modulating the mobility of proteins and lipids in the membrane, facilitating their segregation, and influencing their clustering. This organization plays a critical role in receptor-mediated signaling, especially in the case of immunoreceptors, which require lateral clustering for their activation. Based on recent developments, we discuss the structures and mechanisms whereby the cortical cytoskeleton regulates membrane dynamics and organization, and how the nonuniform distribution of immunoreceptors and their self-association may affect activation and signaling.
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Affiliation(s)
- Khuloud Jaqaman
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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