The coiled-coil trigger site of the rod domain of cortexillin I unveils a distinct network of interhelical and intrahelical salt bridges

Burkhard, Peter; Kammerer, Richard A.; Steinmetz, Michel O.; Bourenkov, Gleb; Aebi, Ueli

doi:10.1016/s0969-2126(00)00100-3

Cited by 116 publications

(104 citation statements)

References 37 publications

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“…Model building indicated that salt bridges between positions e and g were also important and favored the chains being in register (3). The high-resolution structure of the tropomyosin fragment (12) shows both the knobs in holes packing and the e-g salt bridges and in this respect is similar to the structures of other coiledcoils such as the GCN4 leucine zipper (22) and cortexillin (23). There is also a significant variation of radius of coiled-coil associated with different sizes of core side chains.…”

supporting

confidence: 52%

Structural basis for bending tropomyosin around actin in muscle thin filaments

Stewart

2001

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

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supporting

confidence: 52%

Structural basis for bending tropomyosin around actin in muscle thin filaments

Stewart

2001

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

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“…This network is a characteristic feature of the monomeric GCN4 leucine zipper folding intermediate that is rearranged in the final dimeric coiled-coil structure. Notably, networks of intrahelical and interhelical electrostatic interactions are also the hallmark that distinguishes trigger sequences from other heptad repeat regions (17,42). It is interesting to note that GCN4 coiled-coil folding markedly depends on solution conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, understanding the folding mechanisms of coiled coils is of fundamental interest to experimentalists and theoreticians challenged by the question of how the sequence of a protein defines its specific 3D structure. Along these lines, we have been interested particularly in coiled-coil ''trigger sequences,'' which encode stable monomeric ␣-helices that are indispensable for coiled-coil formation (14)(15)(16)(17)(18). Although there are a few examples of synthetic peptides that fold either into heterodimers (19) or at conditions of extremes of pH (20) without an apparent trigger sequence, the ''trigger site'' concept is generally accepted because these short autonomous helical folding units are structurally and functionally conserved in a large number of native coiled-coil proteins (reviewed in refs.…”

mentioning

confidence: 99%

Molecular basis of coiled-coil formation

Steinmetz

Jelesarov

Matousek

et al. 2007

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

124

129

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Coiled coils have attracted considerable interest as design templates in a wide range of applications. Successful coiled-coil design strategies therefore require a detailed understanding of coiled-coil folding. One common feature shared by coiled coils is the presence of a short autonomous helical folding unit, termed ''trigger sequence,'' that is indispensable for folding. Detailed knowledge of trigger sequences at the molecular level is thus key to a general understanding of coiled-coil formation. Using a multidisciplinary approach, we identify and characterize here the molecular determinants that specify the helical conformation of the monomeric early folding intermediate of the GCN4 coiled coil. We demonstrate that a network of hydrogen-bonding and electrostatic interactions stabilize the trigger-sequence helix. This network is rearranged in the final dimeric coiled-coil structure, and its destabilization significantly slows down GCN4 leucine zipper folding. Our findings provide a general explanation for the molecular mechanism of coiled-coil formation.autonomous folding unit ͉ protein folding ͉ trigger sequence ͉ leucine zipper ͉ ␣-helix A lthough coiled coils have been used traditionally as model systems for protein folding studies, the molecular basis of how they fold is still largely unknown. A need for a detailed understanding of coiled-coil folding is relevant, particularly in light of the important functions these structures play in almost all biological processes, as well as the considerable attention coiled coils have recently garnered in a wide range of applications, including basic research, nanomaterials, protein engineering, biotechnology, and medicine (1-13). Furthermore, understanding the folding mechanisms of coiled coils is of fundamental interest to experimentalists and theoreticians challenged by the question of how the sequence of a protein defines its specific 3D structure. Along these lines, we have been interested particularly in coiled-coil ''trigger sequences,'' which encode stable monomeric ␣-helices that are indispensable for coiled-coil formation (14-18). Although there are a few examples of synthetic peptides that fold either into heterodimers (19) or at conditions of extremes of pH (20) without an apparent trigger sequence, the ''trigger site'' concept is generally accepted because these short autonomous helical folding units are structurally and functionally conserved in a large number of native coiled-coil proteins (reviewed in refs. 21-24). Detailed knowledge of the properties of trigger sequences at the molecular level is therefore key to an understanding of coiled-coil formation and function in general.The parallel two-stranded leucine zipper of the yeast transcriptional activator GCN4 is the best-characterized coiled coil and thus represents an excellent paradigm for a comprehensive analysis of the roles of trigger sequences in coiled-coil folding. Our current understanding of the folding kinetics of the GCN4 leucine zipper is based on extensive stopped-flow studies and te...

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“…Inter-and intra-molecular hydrogen-bonded salt bridges are prevalent in the X-ray structure of the GCN4 leucine zipper (Fig. 1), and other coiled coils 12,15,[19][20][21] . By contrast NMR studies have shown that ionization of these residues often contributes little to the stability of the N state 17,22-24 .…”

Section: Introductionmentioning

confidence: 99%

Electrostatic Contributions to the Stability of the GCN4 Leucine Zipper Structure

Matousek

Ciani

Fitch

et al. 2007

Journal of Molecular Biology

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SummaryIon pairs are ubiquitous in X-ray structures of coiled coils, and mutagenesis of charged residues can result in large stability losses. By contrast, pK a values determined by NMR in solution often predict only small contributions to stability from charge interactions. To help reconcile these results we used triple-resonance NMR to determine pK a values for all groups that ionize between pH 1 and 13 in the 33-residue leucine zipper fragment, GCN4p. In addition to the native state we also determined comprehensive pK a values for two models of the GCN4p denatured state: the protein in 6 M urea, and unfolded peptide fragments of the protein in water. Only residues that form ion pairs in multiple X-ray structures of GCN4p gave large pK a differences between the native and denatured states. Moreover, electrostatic contributions to stability were not equivalent for oppositely charged partners in ion pairs, suggesting that the interactions between a charge and its environment are as important as those within the ion pair. The pH dependence of protein stability calculated from NMR-derived pK a values agreed with the stability profile measured from equilibrium urea-unfolding experiments as a function of pH. The stability profile was also reproduced with structure-based continuum electrostatic calculations, although contributions to stability were overestimated at the extremes of pH. We consider potential sources of errors in the calculations, and how pK a predictions could be improved. Our results show that although hydrophobic packing and hydrogen bonding have dominant roles, electrostatic interactions also make significant contributions to the stability of the coiled coil.

show abstract

The coiled-coil trigger site of the rod domain of cortexillin I unveils a distinct network of interhelical and intrahelical salt bridges

Cited by 116 publications

References 37 publications

Structural basis for bending tropomyosin around actin in muscle thin filaments

Structural basis for bending tropomyosin around actin in muscle thin filaments

Molecular basis of coiled-coil formation

Electrostatic Contributions to the Stability of the GCN4 Leucine Zipper Structure

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