Single-molecule visualization of dynamic transitions of pore-forming peptides among multiple transmembrane positions

Liu, Ying; Qian, Zhenyu; Ma, Li; Hu, Shuxin; Nong, Daguan; Xu, Chong; Ye, Fangfu; Lü, Ying; Wei, Guanghong; Li, Ming

doi:10.1038/ncomms12906

Cited by 38 publications

(56 citation statements)

References 46 publications

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“…The results are in accordance with the expectation that the floppy ssDNA is in close proximity to the liposome surface, while the rigid dsDNA stands upright on the surface . We also applied LipoFRET to the LL‐37 peptide and obtained similar results as in our previous work on solid‐supported lipid bilayers (Supporting Information, Figure S5), further demonstrating the validation of LipoFRET.…”

Section: Figuresupporting

confidence: 89%

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Hou

et al. 2019

Angewandte Chemie

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Tracking membrane‐interacting molecules and visualizing their conformational dynamics are key to understanding their functions. It is, however, challenging to accurately probe the positions of a molecule relative to a membrane. Herein, a single‐molecule method, termed LipoFRET, is reported to assess interplay between molecules and liposomes. It takes advantage of FRET between a single fluorophore attached to a biomolecule and many quenchers in a liposome. This method was used to characterize interactions between α‐synuclein (α‐syn) and membranes. These results revealed that the N‐terminus of α‐syn inserts into the membrane and spontaneously transitions between different depths. In contrast, the C‐terminal tail of α‐syn is regulated by calcium ions and floats in solution in two conformations. LipoFRET is a powerful tool to investigate membrane‐interacting biomolecules with sub‐nanometer precision at the single‐molecule level.

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Section: Figuresupporting

confidence: 89%

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Hou

et al. 2019

Angewandte Chemie

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“…The high concentration of sterols in the outer leaflet of host cell membranes may also help prevent LL-37 from inserting into host cell membranes (15, 17). Previous work has shown that at sufficiently high concentration LL-37 not only permeabilizes the Escherichia coli OM and CM (11, 15, 16, 18, 19) but also induces oxidative stress (13).…”

mentioning

confidence: 99%

Rigidification of the Escherichia coli cytoplasm by the human antimicrobial peptide LL-37 revealed by superresolution fluorescence microscopy

Zhu

Mohapatra

Weisshaar

2018

Proc. Natl. Acad. Sci. U.S.A.

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Superresolution, single-particle tracking reveals effects of the cationic antimicrobial peptide LL-37 on the Escherichia coli cytoplasm. Seconds after LL-37 penetrates the cytoplasmic membrane, the chromosomal DNA becomes rigidified on a length scale of ∼30 nm, evidenced by the loss of jiggling motion of specific DNA markers. The diffusive motion of a subset of ribosomes is also frozen. The mean diffusion coefficients of the DNA-binding protein HU and the nonendogenous protein Kaede decrease twofold. Roughly 108 LL-37 copies flood the cell (mean concentration ∼90 mM). Much of the LL-37 remains bound within the cell after extensive rinsing with fresh growth medium. Growth never recovers. The results suggest that the high concentration of adsorbed polycationic peptides forms a dense network of noncovalent, electrostatic linkages within the chromosomal DNA and among 70S-polysomes. The bacterial cytoplasm comprises a concentrated collection of biopolymers that are predominantly polyanionic (e.g., DNA, ribosomes, RNA, and most globular proteins). In normal cells, this provides a kind of electrostatic lubrication, enabling facile diffusion despite high biopolymer volume fraction. However, this same polyanionic nature renders the cytoplasm susceptible to massive adsorption of polycationic agents once penetration of the membranes occurs. If this phenomenon proves widespread across cationic agents and bacterial species, it will help explain why resistance to antimicrobial peptides develops only slowly. The results suggest two design criteria for polycationic peptides that efficiently kill gram-negative bacteria: facile penetration of the outer membrane and the ability to alter the cytoplasm by electrostatically linking double-stranded DNA and 70S-polysomes.

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“…Furthermore, LL-37 synergizes with other host-derived airway antimicrobials in killing bacteria (e.g., defensins and lysozyme) (35,124,129,130). There are multiple posited mechanisms by which LL-37 directly kills bacterial cells: there is evidence in the literature for the carpet model of bacterial killing (131) as well as for a modified, toroidal pore-forming model (132,133), both of which compromise bacterial membrane integrity, resulting in lysis. There is additional evidence that LL-37 preferentially attacks septating (actively growing/dividing) bacterial cells, thereby inhibiting bacterial proliferation (134).…”

Section: Ll-37 An Antimicrobial Peptide With Bactericidal and Immunomentioning

confidence: 99%

Cystic Fibrosis and Pseudomonas aeruginosa: the Host-Microbe Interface

2019

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SUMMARY In human pathophysiology, the clash between microbial infection and host immunity contributes to multiple diseases. Cystic fibrosis (CF) is a classical example of this phenomenon, wherein a dysfunctional, hyperinflammatory immune response combined with chronic pulmonary infections wreak havoc upon the airway, leading to a disease course of substantial morbidity and shortened life span. Pseudomonas aeruginosa is an opportunistic pathogen that commonly infects the CF lung, promoting an accelerated decline of pulmonary function. Importantly, P. aeruginosa exhibits significant resistance to innate immune effectors and to antibiotics, in part, by expressing specific virulence factors (e.g., antioxidants and exopolysaccharides) and by acquiring adaptive mutations during chronic infection. In an effort to review our current understanding of the host-pathogen interface driving CF pulmonary disease, we discuss (i) the progression of disease within the primitive CF lung, specifically focusing on the role of host versus bacterial factors; (ii) critical, neutrophil-derived innate immune effectors that are implicated in CF pulmonary disease, including reactive oxygen species (ROS) and antimicrobial peptides (e.g., LL-37); (iii) P. aeruginosa virulence factors and adaptive mutations that enable evasion of the host response; and (iv) ongoing work examining the distribution and colocalization of host and bacterial factors within distinct anatomical niches of the CF lung.

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Single-molecule visualization of dynamic transitions of pore-forming peptides among multiple transmembrane positions

Cited by 38 publications

References 46 publications

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Rigidification of the Escherichia coli cytoplasm by the human antimicrobial peptide LL-37 revealed by superresolution fluorescence microscopy

Cystic Fibrosis and Pseudomonas aeruginosa: the Host-Microbe Interface

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