(i,i+ 4) Ion Pairs Stabilize Helical Peptides Derived from Smooth Muscle Caldesmon

Wang, Enzhong; Wang, Chih‐Lueh Albert

doi:10.1006/abbi.1996.0204

Cited by 24 publications

(28 citation statements)

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“…Our CD thermal denaturation experiments on full length ezrin show a linear dependence on temperature prior to unfolding (Fig. 3B),which is typical for coiled-coils [46], however, it does not exclude single, stable α-helices [47].…”

Section: Discussionmentioning

confidence: 77%

“…We note that prior to the sigmoidal unfolding transition, the mean residue ellipticity shows a linear dependence on temperature for both full-length monomer and dimer samples. Such a linear dependence on temperature is typical for coiled-coil proteins [46] as well as stable single α-helices [47].…”

Section: Multi-angle Light Scattering Shows Bacterially Expressed Ezrmentioning

confidence: 89%

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Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin

Phang

Harrop

Duff

et al. 2016

Biochemical Journal

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Ezrin is a member of the ERM (ezrin–radixin–moesin) family of proteins that have been conserved through metazoan evolution. These proteins have dormant and active forms, where the latter links the actin cytoskeleton to membranes. ERM proteins have three domains: an N-terminal FERM [band Four-point-one (4.1) ERM] domain comprising three subdomains (F1, F2, and F3); a helical domain; and a C-terminal actin-binding domain. In the dormant form, FERM and C-terminal domains form a stable complex. We have determined crystal structures of the active FERM domain and the dormant FERM:C-terminal domain complex of human ezrin. We observe a bistable array of phenylalanine residues in the core of subdomain F3 that is mobile in the active form and locked in the dormant form. As subdomain F3 is pivotal in binding membrane proteins and phospholipids, these transitions may facilitate activation and signaling. Full-length ezrin forms stable monomers and dimers. We used small-angle X-ray scattering to determine the solution structures of these species. As expected, the monomer shows a globular domain with a protruding helical coiled coil. The dimer shows an elongated dumbbell structure that is twice as long as the monomer. By aligning ERM sequences spanning metazoan evolution, we show that the central helical region is conserved, preserving the heptad repeat. Using this, we have built a dimer model where each monomer forms half of an elongated antiparallel coiled coil with domain-swapped FERM:C-terminal domain complexes at each end. The model suggests that ERM dimers may bind to actin in a parallel fashion.

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Section: Discussionmentioning

confidence: 77%

Section: Multi-angle Light Scattering Shows Bacterially Expressed Ezrmentioning

confidence: 89%

Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin

Phang

Harrop

Duff

et al. 2016

Biochemical Journal

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“…Many putative SAHs have now been identified in a wide range of proteins with diverse functions, typically ranging in length between 40 and ~200 residues12789. However, only a few of these have been characterized experimentally and in detail4569101112. Most recently, it has been shown that in some cases, a region of the SAH can mediate binding to other proteins1314.…”

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confidence: 99%

Characterization of long and stable de novo single alpha-helix domains provides novel insight into their stability

Wolny

Batchelor

Bartlett

et al. 2017

Sci Rep

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Naturally-occurring single α-helices (SAHs), are rich in Arg (R), Glu (E) and Lys (K) residues, and stabilized by multiple salt bridges. Understanding how salt bridges promote their stability is challenging as SAHs are long and their sequences highly variable. Thus, we designed and tested simple de novo 98-residue polypeptides containing 7-residue repeats (AEEEXXX, where X is K or R) expected to promote salt-bridge formation between Glu and Lys/Arg. Lys-rich sequences (EK3 (AEEEKKK) and EK2R1 (AEEEKRK)) both form SAHs, of which EK2R1 is more helical and thermo-stable suggesting Arg increases stability. Substituting Lys with Arg (or vice versa) in the naturally-occurring myosin-6 SAH similarly increased (or decreased) its stability. However, Arg-rich de novo sequences (ER3 (AEEERRR) and EK1R2 (AEEEKRR)) aggregated. Combining a PDB analysis with molecular modelling provides a rational explanation, demonstrating that Glu and Arg form salt bridges more commonly, utilize a wider range of rotamer conformations, and are more dynamic than Glu–Lys. This promiscuous nature of Arg helps explain the increased propensity of de novo Arg-rich SAHs to aggregate. Importantly, the specific K:R ratio is likely to be important in determining helical stability in de novo and naturally-occurring polypeptides, giving new insight into how single α-helices are stabilized.

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“…The corresponding peptides were synthesised, their α-helicity experimentally determined by, for example, circular dichroism, and stabilization energies were obtained by fitting models to the data. Although poly-alanine peptides adopt α-helical conformations when sparsely interrupted by lysine [6], arginine [7] and glutamine residues [8], helices are especially stabilized by charged interactions (salt bridges) between residues at ( i , i+3 ) and ( i , i+4 ) spacing [1–3] and hydrogen-bonding interactions between polar/charged residues at ( i , i+3 ) and ( i , i+4 ) [4,5]. Additional stability is obtained through networks of oppositely charged residues in ( i , i+3 , i+6 ), ( i , i+3 , i+7 ), ( i , i+4 , i+7 ), or ( i , i+4 , i+8 ) distances [9,10].…”

Section: Introductionmentioning

confidence: 99%

Distribution and evolution of stable single α-helices (SAH domains) in myosin motor proteins

2017

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Stable single-alpha helices (SAHs) are versatile structural elements in many prokaryotic and eukaryotic proteins acting as semi-flexible linkers and constant force springs. This way SAH-domains function as part of the lever of many different myosins. Canonical myosin levers consist of one or several IQ-motifs to which light chains such as calmodulin bind. SAH-domains provide flexibility in length and stiffness to the myosin levers, and may be particularly suited for myosins working in crowded cellular environments. Although the function of the SAH-domains in human class-6 and class-10 myosins has well been characterised, the distribution of the SAH-domain in all myosin subfamilies and across the eukaryotic tree of life remained elusive. Here, we analysed the largest available myosin sequence dataset consisting of 7919 manually annotated myosin sequences from 938 species representing all major eukaryotic branches using the SAH-prediction algorithm of Waggawagga, a recently developed tool for the identification of SAH-domains. With this approach we identified SAH-domains in more than one third of the supposed 79 myosin subfamilies. Depending on the myosin class, the presence of SAH-domains can range from a few to almost all class members indicating complex patterns of independent and taxon-specific SAH-domain gain and loss.

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(i,i+ 4) Ion Pairs Stabilize Helical Peptides Derived from Smooth Muscle Caldesmon

Cited by 24 publications

References 0 publications

Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin

Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin

Characterization of long and stable de novo single alpha-helix domains provides novel insight into their stability

Distribution and evolution of stable single α-helices (SAH domains) in myosin motor proteins

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