Using low-E resonators to reduce RF heating in biological samples for static solid-state NMR up to 900MHz

Gor’kov, Peter L.; Chekmenev, Eduard Y.; Li, Conggang; Cotten, Myriam; Buffy, Jarrod J.; Traaseth, Nathaniel J.; Veglia, Gianluigi; Brey, Wallace S.

doi:10.1016/j.jmr.2006.11.008

Cited by 173 publications

(244 citation statements)

References 46 publications

(92 reference statements)

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“…Spectra of [U- 15 N] samples were acquired with 1 k scans and 30-t1 increments, whereas selectively labeled samples required 4-to 12 k scans and Ϸ8 -16 increments. Experiments were performed at 1 H frequencies of 600 and 700 MHz using Bruker (DMX) and Varian (VNMRS) spectrometers, respectively, equipped with low electric field flat-coil probes (64). Additional details are given in the SI Text.…”

Section: Nmr Spectroscopymentioning

confidence: 99%

Structure and topology of monomeric phospholamban in lipid membranes determined by a hybrid solution and solid-state NMR approach

Traaseth

Shi²,

Verardi

et al. 2009

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

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156

194

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Phospholamban (PLN) is an essential regulator of cardiac muscle contractility. The homopentameric assembly of PLN is the reservoir for active monomers that, upon deoligomerization form 1:1 complexes with the sarco(endo)plasmic reticulum Ca 2؉ -ATPase (SERCA), thus modulating the rate of calcium uptake. In lipid bilayers and micelles, monomeric PLN exists in equilibrium between a bent (or resting) T state and a more dynamic (or active) R state. Here, we report the high-resolution structure and topology of the T state of a monomeric PLN mutant in lipid bilayers, using a hybrid of solution and solid-state NMR restraints together with molecular dynamics simulations in explicit lipid environments. Unlike the previous structural ensemble determined in micelles, this approach gives a complete picture of the PLN monomer structure in a lipid bilayer. This hybrid ensemble exemplifies the tilt, rotation, and depth of membrane insertion, revealing the interaction with the lipids for all protein domains. The N-terminal amphipathic helical domain Ia (residues 1-16) rests on the surface of the lipid membrane with the hydrophobic face of domain Ia embedded in the membrane bilayer interior. The helix comprised of domain Ib (residues 23-30) and transmembrane domain II (residues 31-52) traverses the bilayer with a tilt angle of Ϸ24°. The specific interactions between PLN and lipid membranes may represent an additional regulatory element of its inhibitory function. We propose this hybrid method for the simultaneous determination of structure and topology for membrane proteins with compact folds or proteins whose spatial arrangement is dictated by their specific interactions with lipid bilayers.hybrid method ͉ membrane proteins ͉ oriented solid-state NMR ͉ molecular modeling ͉ PISEMA S tructure and topology are central to membrane protein function (1). Recently determined high-resolution structures reveal the compact folds for several membrane proteins, such as electron and proton-conducting proteins involved in photosynthesis and respiration (http://blanco.biomol.uci.edu/ Membrane Proteins xtal.html). However, a significant population of membrane proteins does not possess a compact tertiary fold, but has its fold space defined through interactions of secondary structure elements (helices, turns, and loops) with the lipid membrane, i.e., the topology (1). This is the case for phospholamban (PLN), a mammalian protein that is essential in the regulation of cardiac muscle contractility (2), and that has recently become a major target for gene therapy to ameliorate cardiomyopathies (3, 4). PLN is located in the sarco(endo)plasmic reticulum (SR) of cardiac myocytes, inhibiting the SR Ca 2ϩ -ATPase (SERCA) by shifting its relative Ca 2ϩ affinity (5). In vitro and in vivo experiments have shown PLN to exist as a homopentamer that deoligomerizes into active monomers that bind SERCA in a 1:1 molar ratio (6). The monomeric form of PLN exists in equilibrium between a dynamically disordered R state and a more restricted T state (7,8) and has 3 ...

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Section: Nmr Spectroscopymentioning

confidence: 99%

Structure and topology of monomeric phospholamban in lipid membranes determined by a hybrid solution and solid-state NMR approach

Traaseth

Shi²,

Verardi

et al. 2009

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

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156

194

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“…strength of Ϸ60 kHz for cross-polarization, SEMA, and decoupling, by using a low-E probe (54). Additional details are provided in the SI Methods.…”

mentioning

confidence: 99%

Spectroscopic validation of the pentameric structure of phospholamban

Traaseth¹,

Verardi

Torgersen

et al. 2007

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

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126

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Phospholamban (PLN) regulates calcium translocation within cardiac myocytes by shifting sarco(endo)plasmic reticulum Ca 2؉ -ATPase (SERCA) affinity for calcium. Although the monomeric form of PLN (6 kDa) is the principal inhibitory species, recent evidence suggests that the PLN pentamer (30 kDa) also is able to bind SERCA. To date, several membrane architectures of the pentamer have been proposed, with different topological orientations for the cytoplasmic domain: (i) extended from the bilayer normal by 50 -60°; (ii) continuous ␣-helix tilted 28°relative to the bilayer normal; (iii) pinwheel geometry, with the cytoplasmic helix perpendicular to the bilayer normal and in contact with the surface of the bilayer; and (iv) bellflower structure, in which the cytoplasmic domain helix makes Ϸ20°angle with respect to the membrane bilayer normal. Using a variety of cell membrane mimicking systems (i.e., lipid vesicles, oriented lipid bilayers, and detergent micelles) and a combination of multidimensional solution/solidstate NMR and EPR spectroscopies, we tested the different structural models. We conclude that the pinwheel topology is the predominant conformation of pentameric PLN, with the cytoplasmic domain interacting with the membrane surface. We propose that the interaction with the bilayer precedes SERCA binding and may mediate the interactions with other proteins such as protein kinase A and protein phosphatase 1.Ca 2ϩ -ATPase ͉ EPR ͉ membrane protein ͉ solid-state NMR ͉ protein dynamics C alcium translocation into the sarcoplasmic reticulum of cardiac myocytes is controlled by the sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA). Phospholamban (PLN) regulates the activity of SERCA by shifting the apparent calcium affinity for the enzyme. This activity is relieved by phosphorylation of PLN at Ser-16 and/or Thr-17 and high calcium concentration within the cytosol. Wild-type PLN (wt-PLN) forms stable homopentamers in lipid bilayers and in detergent micelles, where each monomer is composed of a helical cytoplasmic domain (residues 1-16), a semiflexible loop (residues 17-21), and a helical transmembrane domain (residues 22-52) (1, 2). Mutagenesis, molecular biology, and in vivo studies revealed that the PLN pentamer depolymerizes into active monomers that bind and inhibit SERCA (3). Similar conclusions were reached by in vitro fluorescence studies (4). Recently, Young and coworkers (5) have reported a cocrystal formed by SERCA and PLN pentamer, suggesting that the pentameric species also is able to bind SERCA. Furthermore, Jones and coworkers (6) hypothesized that the PLN pentamer may act as a chloride ion channel, which is supported by the bellflower structure recently determined by Oxenoid and Chou (2).There are four principal proposed structural models of pentameric wt-PLN, which differ primarily in the topology of the more dynamic cytoplasmic domain. In each of these models (shown in Fig. 1), residues 32-52 are in a coiled helix approximately parallel to the bilayer normal. The first model (extended helix/sheet ...

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“…43 The spectra of sarcolipin in flipped bicelles were acquired at 38 • C, whereas a temperature of 28 • C was used for the NAL single crystal. Both the 90 • and 180 • pulse lengths on 1 H and 15 N are 4 and 8 μs, respectively, which correspond to a field strength of 62.5 kHz RF (γ B 1 ).…”

Section: B Nmr Spectroscopymentioning

confidence: 99%

Proton evolved local field solid-state nuclear magnetic resonance using Hadamard encoding: Theory and application to membrane proteins

Gopinath¹,

Mote²,

Veglia

2011

The Journal of Chemical Physics

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NMR anisotropic parameters such as dipolar couplings and chemical shifts are central to structure and orientation determination of aligned membrane proteins and liquid crystals. Among the separated local field experiments, the proton evolved local field (PELF) scheme is particularly suitable to measure dynamically averaged dipolar couplings and give information on local molecular motions. However, the PELF experiment requires the acquisition of several 2D datasets at different mixing times to optimize the sensitivity for the complete range of dipolar couplings of the resonances in the spectrum. Here, we propose a new PELF experiment that takes the advantage of the Hadamard encoding (HE) to obtain higher sensitivity for a broad range of dipolar couplings using a single 2D experiment. The HE scheme is obtained by selecting the spin operators with phase switching of hard pulses. This approach enables one to detect four spin operators, simultaneously, which can be processed into two 2D spectra covering a broader range of dipolar couplings. The advantages of the new approach are illustrated for a U-15 N NAL single crystal and the U-15 N labeled single-pass membrane protein sarcolipin reconstituted in oriented lipid bicelles. The HE-PELF scheme can be implemented in other multidimensional experiments to speed up the characterization of the structure and dynamics of oriented membrane proteins and liquid crystalline samples.

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Using low-E resonators to reduce RF heating in biological samples for static solid-state NMR up to 900MHz

Cited by 173 publications

References 46 publications

Structure and topology of monomeric phospholamban in lipid membranes determined by a hybrid solution and solid-state NMR approach

Structure and topology of monomeric phospholamban in lipid membranes determined by a hybrid solution and solid-state NMR approach

Spectroscopic validation of the pentameric structure of phospholamban

Proton evolved local field solid-state nuclear magnetic resonance using Hadamard encoding: Theory and application to membrane proteins

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