Interactions between bovine myelin basic protein and zwitterionic lysophospholipids

Gow, Alexander; Auton, Wendy P.; Smith, Ross

doi:10.1021/bi00457a007

Cited by 15 publications

(3 citation statements)

References 30 publications

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“…Light scattering artifacts were eliminated by use of mixed micelles of LPC/PG (4:1, mol/mol). Micelles of lysophospholipids are generally smaller than 10 nm in diameter, they do not exhibit substantial scattering, and they have been extensively used in CD measurements as mimics for the phospholipid environment for proteins ( − ). The dispersion state of micelles of LPC/PG (4:1, mol/mol) was not affected by CCT (Figure ).…”

Section: Discussionmentioning

confidence: 99%

Lipid-Induced Conformational Switch in the Membrane Binding Domain of CTP:Phosphocholine Cytidylyltransferase: A Circular Dichroism Study

2003

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CTP:phosphocholine cytidylyltranferase (CCT) regulates phosphatidylcholine (PC) biosynthesis. Its activity is controlled by reversible interactions with membrane lipids, mediated by an internal segment referred to as domain M. Although domain M peptides adopt an amphipathic alpha-helical structure when membrane bound, the structure of this domain in the context of the whole enzyme in the lipid-free and lipid-bound state is unknown. Here we derive lipid-induced secondary structural changes in CCTalpha using circular dichroism and three deconvolution programs. The analysis of two fragments, CCT236 (CCT1-236, housing the catalytic domain) and a synthetic domain M peptide (CCT237-293) aided the assignment of structural change to specific domains. To carry out this study, we developed a micellar lipid activating system that would avoid generation of CCT-induced lipid vesicle aggregates that interfere with the CD analysis. Lysophosphatidylcholine/phosphatidylglycerol (LPC/PG) mixed micelles supported full activation of CCT and caused an increase in the alpha-helix content of full-length CCT from 25 to 41%, at the expense of all other conformations. LPC/PG also induced an increase in alpha-helix content of the domain M peptide from 7 to 85% at the expense of all other conformers. This lipid system did not significantly affect the secondary structure of CCT236, nor did it affect the proteolytic fragmentation pattern of this region within full-length CCT, suggesting that the region containing the catalytic domain changes very little upon membrane activation of CCT. Our data suggest that lipids trigger a conformational switch in domain M from a mixed structure to an alpha-helix, thus creating a hydrophobic face for membrane insertion. Our results negate the idea that domain M is entirely helical in both the soluble and membrane-bound forms of CCT.

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Section: Discussionmentioning

confidence: 99%

Lipid-Induced Conformational Switch in the Membrane Binding Domain of CTP:Phosphocholine Cytidylyltransferase: A Circular Dichroism Study

2003

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“…However, the number of temperature points for those anionic lipids where the heat capacity has been measured is less than for phosphatidyl-cholines, and the experimental scatter is greater. Nevertheless, we can test whether the parameters established for phosphatidylcholine are appropriate for a different phospholipid by using a systematic comparison of the temperature dependence for spin-labeled phosphatidylglycerol and the (6), with additional points from the literature (10,11,16,(18)(19)(20)(21)(22)(23)(24)(25)(26))-see Marsh (8). Symbols and annotations as in Fig.…”

Section: Resultsmentioning

confidence: 99%

Equation of State for Phospholipid Self-Assembly

Marsh

2016

Biophysical Journal

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Phospholipid self-assembly is the basis of biomembrane stability. The entropy of transfer from water to self-assembled micelles of lysophosphatidylcholines and diacyl phosphatidylcholines with different chain lengths converges to a common value at a temperature of 44°C. The corresponding enthalpies of transfer converge at ∼-18°C. An equation of state for the free energy of self-assembly formulated from this thermodynamic data depends on the heat capacity of transfer as the sole parameter needed to specify a particular lipid. For lipids lacking calorimetric data, measurement of the critical micelle concentration at a single temperature suffices to define an effective heat capacity according to the model. Agreement with the experimental temperature dependence of the critical micelle concentration is then good. The predictive powers should extend also to amphiphile partitioning and the kinetics of lipid-monomer transfer.

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“…It is also important to note that many of the elements of Scheme are well-known from studies of the interactions of other proteins with amphiphiles. For example, progressive and often positively cooperative binding of amphiphiles to proteins is well-known ( − ). This aggregation often begins well below the cmc of the ligand, i.e., as protein-induced aggregation of ligand monomers or premicelles ( − ).…”

Section: Resultsmentioning

confidence: 99%

Interactions of Soluble Penicillin-Binding Protein 2a of Methicillin-Resistant Staphylococcus aureus with Moenomycin

Graves-Woodward

Pratt

1999

Biochemistry

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Kinetics studies in homogeneous aqueous solution showed that solubilized penicillin-binding protein 2a (sPBP2a) of methicillin-resistant Staphylococcus aureus (a bacterial DD-peptidase) was inhibited by the amphiphilic glycolipid antibiotic moenomycin. Inhibition at the peptidase site was determined by competition experiments between moenomycin and the chromophoric beta-lactam nitrocefin. Under conditions of high salt concentration (1 M NaCl), pseudo-first-order rate constants for the reaction of moenomycin with sPBP2a leading to inhibition of acylation by nitrocefin varied with moenomycin concentration in a biphasic fashion. At low moenomycin concentration (<20 microM) little inhibition occurred, but at higher concentrations a linear increase in rate constant with moenomycin concentration was observed, yielding a second-order rate constant of inhibition of 120 s(-)(1) M(-)(1). Since the cmc of moenomycin under these conditions was shown to be ca. 20 microM, the inhibition was concluded to arise from reaction of sPBP2a with a moenomycin micelle. Protein fluorescence studies showed a pseudo-first-order decrease in fluorescence on reaction of the protein with moenomycin. The variation of this rate constant with moenomycin concentration was consistent with reaction of a moenomycin monomer with the protein with a second-order rate constant of 650 s(-)(1) M(-)(1). This monomer reaction did not occur at the DD-peptidase site since its rate was unaffected by prior acylation of the enzyme by benzylpenicillin; nor did it inhibit reaction at that site by beta-lactams. Under low salt conditions (0.175 M NaCl) where reaction could be studied over a greater range of monomer concentrations since the cmc was ca. 120 microM, similar reactions were involved. Under these circumstances, inhibition was concerted with the reaction of moenomycin monomers, although fast premicellar aggregation of moenomycin with the protein also occurred. All moenomycin interactions with sPBP2a were reversible, as revealed by detergent-extraction chromatography. Lower limits to moenomycin off-rates and equilibrium dissociation constants were 7.7 x 10(-)(4) s(-)(1) and 1.2 microM, respectively. Other amphiphiles did not react in exactly the same manner as moenomycin, indicating some degree of specificity in reactions of the latter. sPBP2a did not have detectable affinity for lipid surfaces (Triton X-114 and phosphatidylglycerol vesicles). A general scheme for reaction of moenomycin with sPBP2a is proposed.

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Interactions between bovine myelin basic protein and zwitterionic lysophospholipids

Cited by 15 publications

References 30 publications

Lipid-Induced Conformational Switch in the Membrane Binding Domain of CTP:Phosphocholine Cytidylyltransferase: A Circular Dichroism Study

Lipid-Induced Conformational Switch in the Membrane Binding Domain of CTP:Phosphocholine Cytidylyltransferase: A Circular Dichroism Study

Equation of State for Phospholipid Self-Assembly

Interactions of Soluble Penicillin-Binding Protein 2a of Methicillin-Resistant Staphylococcus aureus with Moenomycin

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