Dataset Information

Stabilization of the spectrin-like domains of nesprin-1? by the evolutionarily conserved "adaptive" domain.

ABSTRACT: Nesprins are located at the outer and inner membranes of the nuclear envelope and help link the cytoskeleton to the nucleoskeleton. Nesprin-1?, located at the inner nuclear membrane, binds to A-type lamins and emerin and has homology to spectrin-repeat proteins. However, the mechanical and thermodynamic properties of the spectrin-like repeats (SLRs) of nesprin-1? and the potential structural contributions of the unique central domain were untested. In other spectrin superfamily proteins, tandem spectrin-repeat domains undergo cooperatively coupled folding and unfolding. We hypothesized that the large central domain, which interrupts SLRs and is conserved in other nesprin isoforms, might confer unique structural properties. To test this model we measured the thermal unfolding of nesprin-1? fragments using circular dichroism and dynamic light scattering. The SLRs in nesprin-1? were found to have structural and thermodynamic properties typical of spectrins. The central domain had relatively little secondary structure as an isolated fragment, but significantly stabilized larger SLR-containing molecules by increasing their overall helicity, thermal stability and cooperativity of folding. We suggest this domain, now termed the 'adaptive' domain (AD), also strengthens dimerization and inhibits unfolding. Further engineering of the isolated AD, and AD-containing nesprin molecules, may yield new information about the higher-order association of cooperative protein motifs.

SUBMITTER: Zhong Z

PROVIDER: S-EPMC2885798 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Stabilization of the spectrin-like domains of nesprin-1α by the evolutionarily conserved "adaptive" domain.

Zhong Zhixia Z Chang Siwei A SA Kalinowski Agnieszka A Wilson Katherine L KL Dahl Kris Noel KN

Cellular and molecular bioengineering 20100601 2

Nesprins are located at the outer and inner membranes of the nuclear envelope and help link the cytoskeleton to the nucleoskeleton. Nesprin-1α, located at the inner nuclear membrane, binds to A-type lamins and emerin and has homology to spectrin-repeat proteins. However, the mechanical and thermodynamic properties of the spectrin-like repeats (SLRs) of nesprin-1α and the potential structural contributions of the unique central domain were untested. In other spectrin superfamily proteins, tandem ...[more]

PMID: 20563238

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Project description:Despite the sequence homology between acid-sensing ion channels (ASICs) and epithelial sodium channel (ENaCs), these channel families display very different functional characteristics. Whereas ASICs are gated by protons and show a relatively low degree of selectivity for sodium over potassium, ENaCs are constitutively active and display a remarkably high degree of sodium selectivity. To decipher if some of the functional diversity originates from differences within the transmembrane helices (M1 and M2) of both channel families, we turned to a combination of computational and functional interrogations, using statistical coupling analysis and mutational studies on mouse ASIC1a. The coupling analysis suggests that the relative position of M1 and M2 in the upper part of the pore domain is likely to remain constant during the ASIC gating cycle, whereas they may undergo relative movements in the lower part. Interestingly, our data suggest that to account for coupled residue pairs being in close structural proximity, both domain-swapped and nondomain-swapped ASIC M2 conformations need to be considered. Such conformational flexibility is consistent with structural work, which suggested that the lower part of M2 can adopt both domain-swapped and nondomain-swapped conformations. Overall, mutations to residues in the middle and lower pore were more likely to affect gating and/or ion selectivity than those in the upper pore. Indeed, disrupting the putative interaction between a highly conserved Trp/Glu residue pair in the lower pore is detrimental to gating and selectivity, although this interaction might occur in both domain-swapped and nonswapped conformations. Finally, our results suggest that the greater number of larger, aromatic side chains in the ENaC M2 helix may contribute to the constitutive activity of these channels at a resting pH. Together, the data highlight differences in the transmembrane domains of these closely related ion channels that may help explain some of their distinct functional properties.

Dataset Information

Stabilization of the spectrin-like domains of nesprin-1? by the evolutionarily conserved "adaptive" domain.

Publications

Stabilization of the spectrin-like domains of nesprin-1α by the evolutionarily conserved "adaptive" domain.

Similar Datasets

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