Conformation of gramicidin A in phospholipid vesicles: circular dichroism studies of effects of ion binding, chemical modification, and lipid structure

Wallace, B.A.; Veatch, William R.; Blout, E. R.

doi:10.1021/bi00523a018

Cited by 159 publications

(128 citation statements)

References 28 publications

(45 reference statements)

Supporting

Mentioning

111

Contrasting

Unclassified

Order By: Relevance

“…This suggested that aggregation of peptide-bound vesicles was responsible and that absorption flattening (39) contributed to the effects on CD. Similar results have been observed in other studies performed with cationic peptides (30), and it illustrates the ability of these peptides to tie together pairs of vesicles in solution. Because aggregation interferes with CD readings, ratios greater than 1/140 were not used in secondary structure calculations.…”

Section: Analysis Of Pediocin Ach In Aqueous Buffer and L Innocuasupporting

confidence: 90%

Conformational Changes in Pediocin AcH upon Vesicle Binding and Approximation of the Membrane-Bound Structure in Detergent Micelles

et al. 2001

View full text Add to dashboard Cite

Pediocin AcH is a 44-residue antimicrobial peptide with bactericidal potency against Gram-positive bacteria such as Listeria. It belongs to a family of bacteriocins that, when membrane-associated, is predicted to contain β-sheet and α-helical regions. All bacteriocins in this family have a conserved N-terminal disulfide bond. An additional C-terminal disulfide bond in pediocin AcH is thought to confer enhanced potency and broader specificity range against sensitive bacteria. The C-terminal disulfide bond may also affect the conformation of the C-terminus. The secondary structures of pediocin AcH in aqueous solution and vesicles from susceptible cells, as well as the ability of trifluoroethanol (TFE) and detergent systems to induce secondary structures like those induced in vesicles, were studied by circular dichroism (CD) spectroscopy. Like related peptides, pediocin AcH was highly unordered in aqueous solution, 56%. However, it also contained 20% β-strand and 15% β-turn structures. Upon complete binding to vesicles, 32% α-helical structure formed, the unordered structure decreased to 32%, and the β-strand and β-turn structures remained largely unchanged. Thus, a βα domain structure formed in vesicles. The helical structure likely forces the C-terminal tail to loop back on the helix so that the C24−C44 disulfide bond can form. Detergent micelles were superior to TFE in their ability to induce secondary structural fractions in pediocin AcH comparable to those observed in vesicles. This demonstrates the importance of a hydrocarbon−water interface to pediocin AcH structure induction and suggests that it is preferable to use detergent micelles as solvents in NMR studies of pediocin AcH structure. ReceiVed May 21, 2001; ReVised Manuscript ReceiVed September 18, 2001 ABSTRACT: Pediocin AcH is a 44-residue antimicrobial peptide with bactericidal potency against Grampositive bacteria such as Listeria. It belongs to a family of bacteriocins that, when membrane-associated, is predicted to contain -sheet and R-helical regions. All bacteriocins in this family have a conserved N-terminal disulfide bond. An additional C-terminal disulfide bond in pediocin AcH is thought to confer enhanced potency and broader specificity range against sensitive bacteria. The C-terminal disulfide bond may also affect the conformation of the C-terminus. The secondary structures of pediocin AcH in aqueous solution and vesicles from susceptible cells, as well as the ability of trifluoroethanol (TFE) and detergent systems to induce secondary structures like those induced in vesicles, were studied by circular dichroism (CD) spectroscopy. Like related peptides, pediocin AcH was highly unordered in aqueous solution, 56%. However, it also contained 20% -strand and 15% -turn structures. Upon complete binding to vesicles, 32% R-helical structure formed, the unordered structure decreased to 32%, and the -strand and -turn structures remained largely unchanged. Thus, a R domain structure formed in vesicles. The helical structure likely forces th...

show abstract

Section: Analysis Of Pediocin Ach In Aqueous Buffer and L Innocuasupporting

confidence: 90%

Conformational Changes in Pediocin AcH upon Vesicle Binding and Approximation of the Membrane-Bound Structure in Detergent Micelles

et al. 2001

View full text Add to dashboard Cite

show abstract

“…This result suggests that the ion binding site which is located near the channel opening [16] is already present in the gramicidin molecule and is not formed on the entry of an ion. Indeed, circular dichroism studies have indicated that virtually no changes in the helical pore diameter occur upon ion binding [33].…”

Section: Discussionmentioning

confidence: 99%

The different influences of ether and ester phospholipids on the conformation of gramicidin A. A molecular modelling study

Meulendijks

Sonderkamp

Dubois

et al. 1989

Biochimica et Biophysica Acta (BBA) - Biomembranes

View full text Add to dashboard Cite

“…1C) (22,23). Changing the membrane environment (24,25) or the amino acid sequence (18,19,26) can alter the gA folding preference, in some cases promoting the folding into double-stranded (DS) dimeric structures (Fig. 1D).…”

mentioning

confidence: 99%

The Preference of Tryptophan for Membrane Interfaces

Sun

Greathouse

Andersen

et al. 2008

Journal of Biological Chemistry

View full text Add to dashboard Cite

To better understand the structural and functional roles of tryptophan at the membrane/water interface in membrane proteins, we examined the structural and functional consequences of Trp 3 1-methyl-tryptophan substitutions in membranespanning gramicidin A channels. Gramicidin A channels are miniproteins that are anchored to the interface by four Trps near the C terminus of each subunit in a membrane-spanning dimer. We masked the hydrogen bonding ability of individual or multiple Trps by 1-methylation of the indole ring and examined the structural and functional changes using circular dichroism spectroscopy, size exclusion chromatography, solid state 2 H NMR spectroscopy, and single channel analysis. N-Methylation causes distinct changes in the subunit conformational preference, channel-forming propensity, single channel conductance and lifetime, and average indole ring orientations within the membrane-spanning channels. The extent of the local ring dynamic wobble does not increase, and may decrease slightly, when the indole NH is replaced by the non-hydrogen-bonding and more bulky and hydrophobic N-CH 3 group. The changes in conformational preference, which are associated with a shift in the distribution of the aromatic residues across the bilayer, are similar to those observed previously with Trp 3 Phe substitutions. We conclude that indole N-H hydrogen bonding is of major importance for the folding of gramicidin channels. The changes in ion permeability, however, are quite different for Trp 3 Phe and Trp 3 1-methyl-tryptophan substitutions, indicating that the indole dipole moment and perhaps also ring size and are important for ion permeation through these channels.

show abstract

Conformation of gramicidin A in phospholipid vesicles: circular dichroism studies of effects of ion binding, chemical modification, and lipid structure

Cited by 159 publications

References 28 publications

Conformational Changes in Pediocin AcH upon Vesicle Binding and Approximation of the Membrane-Bound Structure in Detergent Micelles

Conformational Changes in Pediocin AcH upon Vesicle Binding and Approximation of the Membrane-Bound Structure in Detergent Micelles

The different influences of ether and ester phospholipids on the conformation of gramicidin A. A molecular modelling study

The Preference of Tryptophan for Membrane Interfaces

Contact Info

Product

Resources

About