Intensity and mosaic spread analysis from PISEMA tensors in solid-state NMR

Quine, J. R.; Achuthan, Srisairam; Asbury, T.; Bertram, Richard; Chapman, Michael S.; Hu, Jun; Cross, Timothy A.

doi:10.1016/j.jmr.2005.12.002

Cited by 21 publications

(37 citation statements)

References 26 publications

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“…This in turn would affect the relative intensity of the resonances in the PISA wheel. As a result, the intensity may be attenuated because Ile-14 is positioned closer than the other residues to the so-called sweet spot, which denotes the minimum intensity point (28). Remarkably, Ile-3 falls in the oriented R-helical region of the PISEMA spectrum, suggesting that the helical conformation extends up to this residue in the lipid bilayer.…”

Section: Assignment Of the Oriented Spectra Of Sln Serca Hasmentioning

confidence: 99%

Two-Dimensional Solid-State NMR Reveals Two Topologies of Sarcolipin in Oriented Lipid Bilayers

et al. 2006

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Sarcolipin (SLN), a 31 amino acid integral membrane protein, regulates SERCA1a and SERCA2a, two isoforms of the sarco(endo)plasmic Ca-ATPase, by lowering their apparent Ca 2+ affinity and thereby enabling muscle relaxation. SLN is expressed in both fast-twitch and slow-twitch muscle fibers with significant expression levels also found in the cardiac muscle. SLN shares ∼30% identity with the transmembrane domain of phospholamban (PLN), and recent solution NMR studies carried out in detergent micelles indicate that the two polypeptides bind to SERCA in a similar manner. Previous 1D solid-state NMR experiments on selectively 15 N-labeled sites showed that SLN crosses the lipid bilayer with an orientation nearly parallel to the bilayer normal. With a view toward the characterization of SLN structure and its interactions with both lipids and SERCA, herein we report our initial structural and topological assignments of SLN in mechanically oriented DOPC/DOPE lipid bilayers as mapped by 2D 15 N PISEMA experiments. The PISEMA spectra obtained on uniformly 15 N-labeled protein as well as 15 N-Leu, 15 N-Ile and 15 N-Val map the secondary structure of SLN and, simultaneously, reveal that SLN exists in two distinct topologies. Both the major and the minor populations assume an orientation with the helix axis tilted by ∼23°with respect to the lipid bilayer normal, but vary in the rotation angle about the helix axis by ∼5°. The existence of the multiple populations in model membranes may be a significant requirement for SLN interaction with SERCA.The integral membrane protein sarcolipin (SLN) is expressed in both fast-twitch and slow-twitch muscle fibers. Recently, significant expression levels of SLN have been identified in cardiac muscle, increasing interest in this protein.In rats and mice, SLN expression is restricted to the heart and skeletal muscle, whereas in humans and rabbits, a different expression pattern is observed (1-4). The different localization pattern amongst species has been attributed to sequence variations in the N-terminal and/or transmembrane residues of SLN. MacLennan and co-workers found that the highly conserved C-terminal tail (RSYQY) of SLN is responsible for the localization of SLN in the endoplasmic reticulum (5).The specific role of SLN in the regulation of heart muscle has yet to be fully understood. One hypothesis is that SLN increases the rate of the leakage of Ca 2+ into the lumen, augmenting ATP hydrolysis mediated heat production (6, 7). A second hypothesis is that SLN physically interacts with SERCA2a in tandem with phospholamban (PLN), its functional homolog, constituting a superinhibitory complex (8).In support of the latter hypothesis, in vivo and in vitro experiments show that SLN alone lowers SERCA's apparent Ca 2+ affinity in a manner similar to that by PLN (9), whereas the simultaneous reconstitution of SLN and PLN produces a superinhibitory effect on SERCA (8).Initially, no posttranslational modifications were identified in SLN co-purified with SERCA (10), leading to the ...

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Section: Assignment Of the Oriented Spectra Of Sln Serca Hasmentioning

confidence: 99%

Two-Dimensional Solid-State NMR Reveals Two Topologies of Sarcolipin in Oriented Lipid Bilayers

et al. 2006

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“…The B 0 coordinates can be expressed as a function of four sign degeneracies {ε 1 , ε 2 , ε 3 , ε 4 } [12,17]. That is, the orientation is determined by the choice of ±1 for each ε.…”

Section: Theory Oriented Structures and Degeneraciesmentioning

confidence: 99%

“…That is, the orientation is determined by the choice of ±1 for each ε. We work with degeneracies that have been expressed mathematically in the principal axis frame (PAF) of the 15 N-1 H dipolar coupling interaction [17]. The definition of all the sign degeneracies were given in [17].…”

Section: Theory Oriented Structures and Degeneraciesmentioning

confidence: 99%

“…The set of possible PISEMA data points corresponding to all B 0 orientations is a powder pattern [12,17,20] (Fig. 1).…”

Section: Theory Oriented Structures and Degeneraciesmentioning

confidence: 99%

“…These restraints give rise to degeneracies [11,12,13,17] in peptide plane orientations. That is, multiple peptide plane orientations are consistent with a given data point.…”

Section: Introductionmentioning

confidence: 99%

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Continuity conditions and torsion angles from ssNMR orientational restraints

Achuthan¹,

Asbury²,

Hu³

et al. 2008

Journal of Magnetic Resonance

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The backbone torsion angle pair (φ, ψ) at each amino acid of a polypeptide is a descriptor of its conformation. One can use chemical shift and dipolar coupling data from solid-state NMR PISEMA experiments to directly calculate the torsion angles for the membrane-spanning portion of a protein.However, degeneracies inherent in the data give rise to multiple potential torsion angles between two adjacent peptide planes (a diplane). The molecular backbone structure can be determined by gluing together the consecutive diplanes, as in the PIPATH algorithm [25]. The multiplicities in torsion angles translate to multiplicities in diplane orientations. In this paper, we show that adjacent diplanes can be glued together to form a permissible structure only if they satisfy continuity conditions, described quantitatively here. These restrict the number of potential torsion angle pairs. We rewrite the torsion angle formulas from [22] so that they automatically satisfy the continuity conditions. The reformulated torsion angle formulas have been applied recently in the PIPATH algorithm [25] and will be helpful in other applications in which diplane gluing is used to construct a protein backbone model.

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Aligned Membrane Proteins: Structural Studies

Brey

Cross

2009

Encyclopedia of Magnetic Resonance

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Intensity and mosaic spread analysis from PISEMA tensors in solid-state NMR

Cited by 21 publications

References 26 publications

Two-Dimensional Solid-State NMR Reveals Two Topologies of Sarcolipin in Oriented Lipid Bilayers

Two-Dimensional Solid-State NMR Reveals Two Topologies of Sarcolipin in Oriented Lipid Bilayers

Continuity conditions and torsion angles from ssNMR orientational restraints

Aligned Membrane Proteins: Structural Studies

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