Solid‐state NMR studies of the membrane‐bound closed state of the colicin E1 channel domain in lipid bilayers

Kim, Yongae; Valentine, Kathleen G.; Opella, Stanley J.; Schendel, Sharon L.

doi:10.1002/pro.5560070214

Cited by 88 publications

(96 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most of the ␣-helical hairpin antimicrobial peptides, such as cecropins (26 -28, 39, 43) and those found in the C-terminal region of colicins (29,31), are active against both Gram-positive and Gram-negative bacteria by disrupting bacterial membrane function. The cellular target for most ␣-helix peptides is the cytoplasmic membrane.…”

Section: Discussionmentioning

confidence: 99%

A Helix-Loop-Helix Peptide at the Upper Lip of the Active Site Cleft of Lysozyme Confers Potent Antimicrobial Activity with Membrane Permeabilization Action

Ibrahim¹,

Thomas²,

Pellegrini³

2001

Journal of Biological Chemistry

259

203

View full text Add to dashboard Cite

Recently, we have found that partially unfolded lysozyme exerts broad spectrum antimicrobial action in vitro against Gram-negative and Gram-positive bacteria independent of its catalytic activity. In parallel, an internal peptide (residues 98 -112) of hen egg white lysozyme, obtained after digestion with clostripain, possessed broad spectrum antimicrobial action in vitro. This internal peptide is part of a helix-loop-helix domain (87-114 sequence of hen lysozyme) located at the upper lip of the active site cleft of lysozyme. The helix-loophelix (HLH) structures are known motifs commonly found in membrane-active and DNA-binding proteins. To evaluate the contribution of the HLH peptide to the antimicrobial properties of lysozyme, the HLH sequence and its secondary structure derivatives of chicken and human lysozyme were synthesized and tested for antimicrobial activity against several bacterial strains. We found that the full HLH peptide of both chicken and human lysozymes was potently microbicidal against both Gram-positive and Gram-negative bacteria and the fungus Candida albicans. The N-terminal helix of HLH was specifically bactericidal to Gram-positive bacteria, whereas the C-terminal helix was bactericidal to all tested strains. Outer and inner membrane permeabilization studies, as well as measurements of transmembrane electrochemical potentials, provided evidence that HLH peptide and its C-terminal helix domain kill Gram-negative bacteria by crossing the outer membrane via self-promoted uptake and causing damage to the inner membrane through channel formation. The results are discussed in terms of proposed mechanisms for the catalytically independent antimicrobial activity of lysozyme that offer a new strategy for the design of potential antimicrobial drugs in the treatment of infectious diseases.

show abstract

Section: Discussionmentioning

confidence: 99%

A Helix-Loop-Helix Peptide at the Upper Lip of the Active Site Cleft of Lysozyme Confers Potent Antimicrobial Activity with Membrane Permeabilization Action

Ibrahim¹,

Thomas²,

Pellegrini³

2001

Journal of Biological Chemistry

259

203

View full text Add to dashboard Cite

show abstract

“…The membrane-bound state of the colicin E1 channel domain is a flexible highly helical (80-90%) extended (4,200 Å 2 per molecule) 2D array of weakly or noninteracting helices anchored by a hydrophobic hairpin (50,51) near the C terminus (Fig. 6).…”

Section: Discussionmentioning

confidence: 99%

Membrane-bound state of the colicin E1 channel domain as an extended two-dimensional helical array

Zakharov

Lindeberg

Griko

et al. 1998

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

View full text Add to dashboard Cite

Atomic level structures have been determined for the soluble forms of several colicins and toxins, but the structural changes that occur after membrane binding have not been well characterized. Changes occurring in the transition from the soluble to membrane-bound state of the C-terminal 190-residue channel polypeptide of colicin E1 (P190) bound to anionic membranes are described. In the membrane-bound state, the ␣-helical content increases from 60-64% to 80-90%, with a concomitant increase in the average length of the helical segments from 12 to 16 or 17 residues, close to the length required to span the membrane bilayer in the open channel state. The average distance between helical segments is increased and interhelix interactions are weakened, as shown by a major loss of tertiary structure interactions, decreased efficiency of fluorescence resonance energy transfer from an energy donor on helix V of P190 to an acceptor on helix IX, and decreased resonance energy transfer at higher temperatures, not observed in soluble P190, implying freedom of motion of helical segments. Weaker interactions are also shown by a calorimetric thermal transition of low cooperativity, and the extended nature of the helical array is shown by a 3-to 4-fold increase in the average area subtended per molecule to 4,200 Å 2 on the membrane surface. The latter, with analysis of the heat capacity changes, implies the absence of a developed hydrophobic core in the membrane-bound P190. The membrane interfacial layer thus serves to promote formation of a highly helical extended two-dimensional flexible net. The properties of the membrane-bound state of the colicin channel domain (i.e., hydrophobic anchor, lengthened and loosely coupled ␣-helices, and close association with the membrane interfacial layer) are plausible structural features for the state that is a prerequisite for voltage gating, formation of transmembrane helices, and channel opening.

show abstract

“…Next, the translocation domain associates with the trimeric ␤-barrel TolC outer membrane receptor, through which the unfolded translocation and catalytic domains of the colicin are transported into the periplasmic space (16). The catalytic domain subsequently refolds into an insertion-competent conformation, and the protein binds the inner membrane and, in a series of kinetically defined steps, the channel protein sequentially unfolds, binds, and spontaneously inserts into the membrane in a precursor state to the open channel (7,(17)(18)(19). The channel is opened upon imposition of a trans-negative membrane potential (20), and the newly created pore causes depolarization of the cytoplasmic membrane through the escape of cellular ions such as Na ϩ , K ϩ , and H ϩ .…”

mentioning

confidence: 99%

“…brane and in-plane ␣-helices of membrane-bound colicin E1 (18), whereas circular dichroism, Fourier transform infrared spectroscopy, fluorescence resonance energy transfer, and differential scanning calorimetry were used to study membrane association and determine the ␣-helical and ␤-sheet content (32). Using site-directed mutagenesis to engineer conveniently located Trp residues, our group has estimated the depth of colicin E1 helical segments upon binding to the membrane using fluorescence quenching, fluorescence resonance energy transfer, and red-edge excitation shift analysis (33)(34)(35).…”

mentioning

confidence: 99%

Toward Elucidating the Membrane Topology of Helix Two of the Colicin E1 Channel Domain

White

Musse

Wang

et al. 2006

Journal of Biological Chemistry

View full text Add to dashboard Cite

The membrane-bound closed state of the colicin E1 channel domain was investigated by site-directed fluorescence labeling using a bimane fluorophore attached to each single cysteine residue within helix 2 of each mutant protein. The fluorescence properties of the bimane fluorophore were measured for the membrane-associated form of the closed channel and included fluorescence emission maximum, fluorescence anisotropy, apparent polarity, surface accessibility, and membrane bilayer penetration depth. The fluorescence data show that helix 2 is an amphipathic ␣-helix that is situated parallel to the membrane surface, but it is less deeply embedded within the bilayer interfacial region than is helix 1 in the closed channel. A least squares fit of the various data sets to a harmonic wave function indicated that the periodicity and angular frequency for helix 2 in the membrane-bound state are typical for an amphipathic ␣-helix (3.8 ؎ 0.1 residues per turn and 94 ؎ 4°, respectively) that is located at an interfacial region of a membrane bilayer. Dual quencher analysis also revealed that helix 2 is peripherally membrane associated, with one face of the helix dipping into the interfacial region of the lipid bilayer and the other face projecting outwardly into the aqueous solvent. Finally, our data show that helices 1 and 2 remain independent helices upon membrane association with a short connector link (Tyr 363 -Gly 364 ) and that short amphipathic ␣-helices participate in the formation of a lipiddependent, toroidal pore for this colicin.

show abstract

Solid‐state NMR studies of the membrane‐bound closed state of the colicin E1 channel domain in lipid bilayers

Cited by 88 publications

References 39 publications

A Helix-Loop-Helix Peptide at the Upper Lip of the Active Site Cleft of Lysozyme Confers Potent Antimicrobial Activity with Membrane Permeabilization Action

A Helix-Loop-Helix Peptide at the Upper Lip of the Active Site Cleft of Lysozyme Confers Potent Antimicrobial Activity with Membrane Permeabilization Action

Membrane-bound state of the colicin E1 channel domain as an extended two-dimensional helical array

Toward Elucidating the Membrane Topology of Helix Two of the Colicin E1 Channel Domain

Contact Info

Product

Resources

About