Dissociation and unfolding of GCN4 leucine zipper in the presence of sodium dodecyl sulfate

Meng, Fanyue; Zeng, Xiangang; Hong, Yuan-Kai; Zhou, Hai‐Meng

doi:10.1016/s0300-9084(01)01340-2

Cited by 18 publications

(22 citation statements)

References 33 publications

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“…Although it is commonly held that addition of SDS leads to unfolding of proteins in solution, SDS has been shown to promote the formation of secondary structure in many proteins [14], [17], [18]. For example, the component proteins of the leucine zipper GCN4 are stabilised as individual α-helices at SDS concentrations above 1 mM [19]. If the AmelF3 proteins are stabilised as α-helices by the presence of SDS then this may promote coiled coil formation as the SDS is removed.…”

Section: Resultsmentioning

confidence: 99%

Single Honeybee Silk Protein Mimics Properties of Multi-Protein Silk

Sutherland

Church

et al. 2011

PLoS ONE

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Honeybee silk is composed of four fibrous proteins that, unlike other silks, are readily synthesized at full-length and high yield. The four silk genes have been conserved for over 150 million years in all investigated bee, ant and hornet species, implying a distinct functional role for each protein. However, the amino acid composition and molecular architecture of the proteins are similar, suggesting functional redundancy. In this study we compare materials generated from a single honeybee silk protein to materials containing all four recombinant proteins or to natural honeybee silk. We analyse solution conformation by dynamic light scattering and circular dichroism, solid state structure by Fourier Transform Infrared spectroscopy and Raman spectroscopy, and fiber tensile properties by stress-strain analysis. The results demonstrate that fibers artificially generated from a single recombinant silk protein can reproduce the structural and mechanical properties of the natural silk. The importance of the four protein complex found in natural silk may lie in biological silk storage or hierarchical self-assembly. The finding that the functional properties of the mature material can be achieved with a single protein greatly simplifies the route to production for artificial honeybee silk.

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Section: Resultsmentioning

confidence: 99%

Single Honeybee Silk Protein Mimics Properties of Multi-Protein Silk

Sutherland

Church

et al. 2011

PLoS ONE

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“…From CD spectroscopy curves, it can be deduced that both peptides adopt an ␣-helical secondary structure in membrane-mimetic environment. The ratio of the minima ( 222 / 208 ) indicates a monomeric structure in TFE and SDS, whereas those peptides form aggregates in the presence of negatively charged phosphatidylglycerol liposomes (31,32). In this context, it would be tempting to suggest the formation of covalent dimers in NK-2 via cysteine residues resulting in an impaired activity compared with cysteine-free NK27.…”

Section: Discussionmentioning

confidence: 99%

Rationale for the Design of Shortened Derivatives of the NK-lysin-derived Antimicrobial Peptide NK-2 with Improved Activity against Gram-negative Pathogens

AndrÃ¤

Monreal

Tejada

et al. 2007

Journal of Biological Chemistry

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The peptide NK-2 is an effective antimicrobial agent with low hemolytic and cytotoxic activities and is thus a promising candidate for clinical applications. It comprises the ␣-helical, cationic core region of porcine NK-lysin a homolog of human granulysin and of amoebapores of pathogenic amoeba. Here we visualized the impact of NK-2 on Escherichia coli by electron microscopy and used NK-2 as a template for sequence variations to improve the peptide stability and activity and to gain insight into the structure/ function relationships. We synthesized 18 new peptides and tested their activities on seven Gram-negative and one Gram-positive bacterial strains, human erythrocytes, and HeLa cells. Although all peptides appeared unordered in buffer, those active against bacteria adopted an ␣-helical conformation in membrane-mimetic environments like trifluoroethanol and negatively charged phosphatidylglycerol (PG) liposomes that mimick the cytoplasmic membrane of bacteria. This conformation was not observed in the presence of liposomes consisting of zwitterionic phosphatidylcholine (PC) typical for the human cell plasma membrane. The interaction was paralleled by intercalation of these peptides into PG liposomes as determined by FRET spectroscopy. A comparative analysis between biological activity and the calculated peptide parameters revealed that the decisive factor for a broad spectrum activity is not the peptide overall hydrophobicity or amphipathicity, but the possession of a minimal positive net charge plus a highly amphipathic anchor point of only seven amino acid residues (two helical turns).

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“…Fractional helicity was calculated from the dichroic minimum at 222 nm, as described previously (52,53). The 222 / 208 ratio was calculated in order to estimate helix-helix interactions (54).…”

Section: Spectroscopymentioning

confidence: 99%

“…the FTIR experiments. Note that a 222 / 208 ratio larger than 1.0 for all L-amino acid peptides characterizes interacting ␣-helices (54,72). This ratio equals 1.10 for K 5 L 7 , indicating its assembly in LPS.…”

Section: Fig 1 Maximal Dissipation Of the Diffusion Potential In LImentioning

confidence: 99%

A Molecular Mechanism for Lipopolysaccharide Protection of Gram-negative Bacteria from Antimicrobial Peptides

Papo

Shai

2005

Journal of Biological Chemistry

224

218

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Cationic antimicrobial peptides serve as the first chemical barrier between all organisms and microbes. One of their main targets is the cytoplasmic membrane of the microorganisms. However, it is not yet clear why some peptides are active against one particular bacterial strain but not against others. Recent studies have suggested that the lipopolysaccharide (LPS) outer membrane is the first protective layer that actually controls peptide binding and insertion into Gram-negative bacteria. In order to shed light on these interactions, we synthesized and investigated a 12-mer amphipathic ␣-helical antimicrobial peptide (K 5 L 7 ) and its diastereomer (4D-K 5 L 7 ) (containing four D-amino acids). Interestingly, although both peptides strongly bind LPS bilayers and depolarize bacterial cytoplasmic membranes, only the diastereomer kills Gram-negative bacteria. Attenuated total reflectance Fourier transform infrared, CD, and surface plasmon resonance spectroscopies revealed that only the diastereomer penetrates the LPS layer. In contrast, K 5 L 7 binds cooperatively to the polysaccharide chain and the outer phosphate groups. As a result, the self-associated K 5 L 7 is unable to traverse through the tightly packed LPS molecules, revealed by epifluorescence studies with LPS giant unilamellar vesicles. The difference in the peptides' modes of binding is further demonstrated by the ability of the diastereomer to induce LPS miscellization, as shown by transmission electron microscopy. In addition to increasing our understanding of the molecular basis of the protection of bacteria by LPS, this study presents a potential strategy to overcome resistance by LPS, and it should help in the design of antimicrobial peptides for future therapeutic purposes.

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Dissociation and unfolding of GCN4 leucine zipper in the presence of sodium dodecyl sulfate

Cited by 18 publications

References 33 publications

Single Honeybee Silk Protein Mimics Properties of Multi-Protein Silk

Single Honeybee Silk Protein Mimics Properties of Multi-Protein Silk

Rationale for the Design of Shortened Derivatives of the NK-lysin-derived Antimicrobial Peptide NK-2 with Improved Activity against Gram-negative Pathogens

A Molecular Mechanism for Lipopolysaccharide Protection of Gram-negative Bacteria from Antimicrobial Peptides

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