Calmodulin has the Potential to Function as a Ca<sup>2+</sup>-Dependent Adaptor Protein

Yamniuk, Aaron P.; Rainaldi, Mario; Vogel, Hans J.

doi:10.4161/psb.2.5.4155

Cited by 16 publications

(14 citation statements)

References 29 publications

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“…The absence of any significant interaction with the CaM N-lobe is highly intriguing as this means there is a fully functional calcium sensor available in the immediate vicinity of the remainder of the Na V 1.5 calcium sensing apparatus. A general model with independent function of the two lobes of CaM has been hypothesized,52 similar to a previous proposal for the homologous and structurally similar EF-hand protein centrin 53. The mechanism of action of CaM in the complex Na V 1.5 Ca 2+ sensing apparatus seems to provide yet another example of the remarkable adaptability and functional diversity of CaM.…”

Section: Discussionsupporting

confidence: 77%

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Chagot

Chazin

2011

Journal of Molecular Biology

108

123

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The function of the human voltage-gated sodium channel Na V 1.5 is regulated in part by intracellular calcium signals. The ubiquitous calcium sensor protein calmodulin (CaM) is an important part of the complex calcium-sensing apparatus in Na V 1.5. CaM interacts with an IQ motif in the large intracellular C-terminal domain of the channel. Using co-expression and copurification, we have been able to isolate a CaM-IQ motif complex and to determine its highresolution structure in absence of calcium using multi-dimensional solution NMR. Under these conditions, the Na V 1.5 IQ motif interacts with the C-terminal domain (C-lobe) of CaM, with the N-terminal domain remaining free in solution. The structure reveals that the C-lobe adopts a semiopen conformation with the IQ motif bound in a narrow hydrophobic groove. Sequence similarities between voltage-gated sodium channels and voltage-gated calcium channels suggest that the structure of the CaM-Na V 1.5 IQ motif complex can serve as a general model for the interaction between CaM and ion channels IQ motifs under conditions of low calcium. The structure also provides insight into the biochemical basis for disease-associated mutations that map to the IQ motif in Na V 1.5.

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Section: Discussionsupporting

confidence: 77%

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Chagot

Chazin

2011

Journal of Molecular Biology

108

123

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“…Generally, the binding region on the target protein is a stretch of about 20 amino acids, with high hydrophobic content and a tendency to form α-helices. CaMBD binding is largely driven by hydrophobic interactions between “anchor” residues on the target and methionine side chains in the CaM pocket, which become exposed upon Ca 2+ binding (Yamniuk et al, 2007 ; Marshall et al, 2015 ). The binding mechanism can be very diverse, resulting in different tuning of target protein properties.…”

Section: Introductionmentioning

confidence: 99%

“…The two CaM domains can interact with the same CaMBD (typical “wrap around” mode) or the N- and C- lobe may bind the different domains independently. In the latter case, CaM acts as an adaptor protein: the binding can promote structural reorganization if the two target domains are on the same protein, or induce dimerization when different proteins are involved (Yamniuk et al, 2007 ). Here, we present a novel interaction between dCRY and CaM.…”

Section: Introductionmentioning

confidence: 99%

Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors

Mazzotta

Bellanda

Minervini

et al. 2018

Front. Mol. Neurosci.

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Light is the main environmental stimulus that synchronizes the endogenous timekeeping systems in most terrestrial organisms. Drosophila cryptochrome (dCRY) is a light-responsive flavoprotein that detects changes in light intensity and wavelength around dawn and dusk. We have previously shown that dCRY acts through Inactivation No Afterpotential D (INAD) in a light-dependent manner on the Signalplex, a multiprotein complex that includes visual-signaling molecules, suggesting a role for dCRY in fly vision. Here, we predict and demonstrate a novel Ca2+-dependent interaction between dCRY and calmodulin (CaM). Through yeast two hybrid, coimmunoprecipitation (Co-IP), nuclear magnetic resonance (NMR) and calorimetric analyses we were able to identify and characterize a CaM binding motif in the dCRY C-terminus. Similarly, we also detailed the CaM binding site of the scaffold protein INAD and demonstrated that CaM bridges dCRY and INAD to form a ternary complex in vivo. Our results suggest a process whereby a rapid dCRY light response stimulates an interaction with INAD, which can be further consolidated by a novel mechanism regulated by CaM.

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“…On its own, the isolated N-terminal lobe of CaM is capable of binding other CBD peptides [56], [103], [104], as well as intact target proteins [105]. Furthermore, related EF-hand proteins have been shown to act as adaptor proteins including centrin and Ca 2+ - and integrin-binding protein 1 [106]. Finally, Ca 2+ -CaM itself can facilitate the movement of large molecules into the nucleus [107], [108], potentially playing a key role in the nuclear targeting of Lf.…”

Section: Discussionmentioning

confidence: 99%

Structural Characterization of the Interaction of Human Lactoferrin with Calmodulin

2012

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Lactoferrin (Lf) is an 80 kDa, iron (Fe3+)-binding immunoregulatory glycoprotein secreted into most exocrine fluids, found in high concentrations in colostrum and milk, and released from neutrophil secondary granules at sites of infection and inflammation. In a number of cell types, Lf is internalized through receptor-mediated endocytosis and targeted to the nucleus where it has been demonstrated to act as a transcriptional trans-activator. Here we characterize human Lf’s interaction with calmodulin (CaM), a ubiquitous, 17 kDa regulatory calcium (Ca2+)-binding protein localized in the cytoplasm and nucleus of activated cells. Due to the size of this intermolecular complex (∼100 kDa), TROSY-based NMR techniques were employed to structurally characterize Ca2+-CaM when bound to intact apo-Lf. Both CaM’s backbone amides and the ε-methyl group of key methionine residues were used as probes in chemical shift perturbation and cross-saturation experiments to define the binding interface of apo-Lf on Ca2+-CaM. Unlike the collapsed conformation through which Ca2+-CaM binds the CaM-binding domains of its classical targets, Ca2+-CaM assumes an extended structure when bound to apo-Lf. Apo-Lf appears to interact predominantly with the C-terminal lobe of Ca2+-CaM, enabling the N-terminal lobe to potentially bind another target. Our use of intact apo-Lf has made possible the identification of a secondary interaction interface, removed from CaM’s primary binding domain. Secondary interfaces play a key role in the target’s response to CaM binding, highlighting the importance of studying intact complexes. This solution-based approach can be applied to study other regulatory calcium-binding EF-hand proteins in intact intermolecular complexes.

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Calmodulin has the Potential to Function as a Ca²⁺-Dependent Adaptor Protein

Cited by 16 publications

References 29 publications

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors

Structural Characterization of the Interaction of Human Lactoferrin with Calmodulin

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Calmodulin has the Potential to Function as a Ca2+-Dependent Adaptor Protein

Cited by 16 publications

References 29 publications

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Solution NMR Structure of Apo-Calmodulin in Complex with the IQ Motif of Human Cardiac Sodium Channel NaV1.5

Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors

Structural Characterization of the Interaction of Human Lactoferrin with Calmodulin

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Calmodulin has the Potential to Function as a Ca²⁺-Dependent Adaptor Protein