Interaction of Poly(L-Lysine)-g-Poly(Ethylene Glycol) with Supported Phospholipid Bilayers

Rossetti, Fernanda F.; Reviakine, Ilya; Csúcs, Gábor; Assi, Fabiano; Vörös, János; Textor, Marcus

doi:10.1529/biophysj.104.041780

Cited by 53 publications

(51 citation statements)

References 75 publications

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“…A ratio of Ͼ1 indicates transcriptional activation due to the presence of a specific compound. (28,61,71). Under the employed growth condition, the most distinct resistance phenotypes for the wild-type strain in comparison to the ⌬PA0920 strain were observed in the presence of ampicillin, oxacillin, cefsulodin, daptomycin, protamine sulfate, poly-L-lysine, and polymyxin E (compare structures denoted in Fig.…”

Section: Resultsmentioning

confidence: 99%

Resistance Phenotypes Mediated by Aminoacyl-Phosphatidylglycerol Synthases

et al. 2012

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The specific aminoacylation of the phospholipid phosphatidylglycerol (PG) with alanine or with lysine catalyzed by aminoacylphosphatidylglycerol synthases (aaPGS) was shown to render various organisms less susceptible to antibacterial agents. This study makes use of Pseudomonas aeruginosa chimeric mutant strains producing lysyl-phosphatidylglycerol (L-PG) instead of the naturally occurring alanyl-phosphatidylglycerol (A-PG) to study the resulting impact on bacterial resistance. Consequences of such artificial phospholipid composition were studied in the presence of an overall of seven antimicrobials (␤-lactams, a lipopeptide antibiotic, cationic antimicrobial peptides [CAMPs]) to quantitatively assess the effect of A-PG substitution (with L-PG, L-PG and A-PG, increased A-PG levels). For the employed Gram-negative P. aeruginosa model system, an exclusive charge repulsion mechanism does not explain the attenuated antimicrobial susceptibility due to PG modification. Additionally, the specificity of nine orthologous aaPGS enzymes was experimentally determined. The newly characterized protein sequences allowed for the establishment of a significant group of A-PG synthase sequences which were bioinformatically compared to the related group of L-PG synthesizing enzymes. The analysis revealed a diverse origin for the evolution of A-PG and L-PG synthases, as the specificity of an individual enzyme is not reflected in terms of a characteristic sequence motif. This finding is relevant for future development of potential aaPGS inhibitors.

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Section: Resultsmentioning

confidence: 99%

Resistance Phenotypes Mediated by Aminoacyl-Phosphatidylglycerol Synthases

et al. 2012

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“…The concentration of proteoliposomes was empirically adjusted to achieve a surface density of Ͻ10 particles per fluorescence image (5 ϫ 5 m). The rupture of vesicles upon nonspecific surface binding cannot be excluded, but surface coating with poly-L-lysine has been reported to prevent disruption of lipid vesicles on the bare glass interface and is a standard technique for cell and protein adhesion (48,49). Single particles were excited at 633 nm with a repetition rate of 76 MHz (Coherent Mira 900F coupled to a Coherent MIRA OPO), and fluorescence spectra, intensities, and lifetimes were measured at room temperature on a home-built confocal fluorescence setup as described in detail earlier (50).…”

Section: Methodsmentioning

confidence: 99%

Light-harvesting Complexes (LHCs) Cluster Spontaneously in Membrane Environment Leading to Shortening of Their Excited State Lifetimes

Natali

Gruber

Dietzel

et al. 2016

Journal of Biological Chemistry

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The light reactions of photosynthesis, which include lightharvesting and charge separation, take place in the amphiphilic environment of the thylakoid membrane. The light-harvesting complex II (LHCII) is the main responsible for light absorption in plants and green algae and is involved in photoprotective mechanisms that regulate the amount of excited states in the membrane. The dual function of LHCII has been extensively studied in detergent micelles, but recent results have indicated that the properties of this complex differ in a lipid environment. In this work we checked these suggestions by studying LHCII in liposomes. By combining bulk and single molecule measurements, we monitored the fluorescence characteristics of liposomes containing single complexes up to densely packed proteoliposomes. We show that the natural lipid environment per se does not alter the properties of LHCII, which for single complexes remain very similar to that in detergent. However, we show that LHCII has the strong tendency to cluster in the membrane and that protein interactions and the extent of crowding modulate the lifetimes of the excited state in the membrane. Finally, the presence of LHCII monomers at low concentrations of complexes per liposome is discussed.Photosynthetic organisms evolved the capacity to harvest the energy of solar radiation and store it into chemical compounds. In vascular plants and green algae, sunlight is absorbed by a series of membrane proteins called light-harvesting complexes (LHC).3 The most abundant of these pigment-protein complexes is LHCII. The LHCs have a dual function; in low light conditions they absorb solar energy and efficiently transfer the excitation energy to the reaction center, and in high light they additionally play a role in photoprotection by dissipating the energy absorbed in excess as heat (1, 2). This last process called non-photochemical quenching (NPQ) leads to a decrease of the excited state lifetime of chlorophyll a (Chl a), limiting the possibility of Chl triplet formation and thus the production of singlet oxygen (3). The fast, on the timescale of seconds, and fully reversible part of NPQ is called qE. This mechanism is triggered by the acidification of the lumenal space of the thylakoids, which activates PsbS (4) and LhcSR (5), the proteins responsible for NPQ in plants and green algae, respectively, and the violaxanthin de-epoxidase, which converts violaxanthin into zeaxanthin (for reviews, see Refs. 6 and 7). Although the precise molecular mechanism of quenching has not been fully elucidated yet, a prominent idea discussed in literature is that NPQ is regulated via conformational changes of LHCII. Those changes could be correlated to, or even caused by, LHCII aggregation (8, 9). It was observed that low pH and zeaxanthin, both occurring in high light, enhance LHCII aggregation (10). Aggregation of LHCII in vitro is accompanied by a decrease of the Chl a fluorescence yield, indicating an increased rate of energy dissipation (9, 11). The generation of new quenching sit...

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“…The optical rotatory dispersion (ORD) of poly(e-benzyloxycarbonyl-L-lysine) has been measured in DCA-CHCl 3 solution [73] and DMF [84]. Fasman et al [73] determined the optical rotation a ½ 546 25 of high molecular weight PLL(Z) in CHCl 3 to be +5°.…”

Section: Gpc and Polarimetrymentioning

confidence: 99%

“…PEG and PLL have been covalently combined to form graft [24,25], diblock [26][27][28][29], triblock [30][31][32], and random [33] copolymers and dendrimers [34,35]; some of which have been conjugated to other moieties, such as: folates [36], acids [37,38], sugars [39,40], RGD [41,42], and amphotericin B [43], to mention a few. They have also been used in polyion complex (PIC) formation [27,44,45], and investigated for drug [46,47] and gene [48][49][50] delivery, colloidal lithography [51,52], biomimetic applications [53], photodynamic therapy (PDT) [54,55], antithrombogenicity [56], and as bioimaging agents [57,58].…”

Section: Introductionmentioning

confidence: 99%