Calcium-induced increase in the radius of gyration and maximum dimension of calmodulin measured by small-angle x-ray scattering

Seaton, Barbara A.; Head, James F.; Engelman, Donald M.; Richards, Frederic M.

doi:10.1021/bi00345a002

Cited by 138 publications

(137 citation statements)

References 18 publications

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“…This changes the overall conformation of the protein from the extended structure of apoCaM to the more extended characteristic dumbbell shape of Ca 2+ CaM. This increase in radius of gyration (R g ) of the protein was observed in small-angle X-ray scattering (SAXS) studies (Seaton et al, 1985;Heidorn et al, 1989;Matsushima et al, 1989Matsushima et al, , 2000.…”

Section: Introductionmentioning

confidence: 93%

Binding of trifluoperazine to apocalmodulin revealed by a combination of small-angle X-ray scattering and nuclear magnetic resonance

et al. 2007

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Small-angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) studies were performed to investigate the binding of trifluoperazine (TFP) to Ca 2+ -free calmodulin (apoCaM) with N-and C-terminal globular domains connected by a linker. The SAXS and NMR measurements were taken throughout the titration of TFP. The SAXS analyses indicate that the binding of TFP induces structural changes from a dumbbell shape to a compact globular shape in solution. The formation of the complete globular structure requires 5.0 added equivalents of TFP. An analysis of NMR chemical-shift changes indicates that the C-terminal domain of apoCaM is involved in the binding of TFP. The SAXS and NMR data reflect the high structural flexibility of apoCaM.

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Section: Introductionmentioning

confidence: 93%

Binding of trifluoperazine to apocalmodulin revealed by a combination of small-angle X-ray scattering and nuclear magnetic resonance

et al. 2007

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“…Recently, incorporation of Tyr-138 into the exiting a-helix of site 4 has been shown to be a calcium-induced event (Kuboniwa et al, 1995) One possible mechanism whereby N-terminal calcium binding might affect Tyr-138 is by direct interaction between the two terminal lobes of the protein. However, although the two lobes can approach more closely in solution than indicated by the crystal structure (Seaton et al, 1985;Heidorn & Trewhella, 1988), no NOE interactions are detected between side chains located in opposing terminal lobes of calmodulin in either the apo-or the holo-form of the protein (Ikuraet al, 1991). Therefore, on the time scale detected by NMR, no residues of the N-terminus are within 5 A of any C-terminal residues, suggesting that direct interaction between the two terminal lobes is unlikely.…”

Section: Analysis In Terms Of the Known Properties Of Tyr-138mentioning

confidence: 99%

“…SAXS analysis has indicated that the terminal lobes of the protein are maintained in the absence of calcium, but are closer together by about 5 A (Seaton et al, 1985;Heidorn & Trewhella, 1988). Nevertheless, biophysical and biochemical studies with both the intact protein and the separated N-and C-terminal halves have suggested that the calcium-induced conformational changes in the two terminal lobes are independent of one another (Forsen et al, 1986;Martin & Bayley, 1986).…”

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confidence: 99%

Interlobe communication in multiple calcium‐binding site mutants of Drosophila calmodulin

1996

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We have generated mutants of Drosophila calmodulin in which pairs of calcium-binding sites are mutated so as to prevent calcium binding. In all sites, the mutation involves replacement of the -Z position glutamate residue with glutamine. Mutants inactivated in both N-terminal sites (B12Q) or both C-terminal sites (B34Q), and two mutants with one N-and one C-terminal site inactivated (B13Q and B24Q) were generated. The quadruple mutant with all four sites mutated was also studied. UV-difference spectroscopy and near-UV CD were used to examine the influence of these mutations upon the single tyrosine (Tyr-138) of the protein. These studies uncovered four situations in which Tyr-138 in the C-terminal lobe responds to a change in the calcium-binding properties of the N-terminal lobe. Further, they suggest that N-terminal calcium-binding events contribute strongly to the aberrant behavior of Tyr-138 seen in mutants with a single functional C-terminal calcium-binding site. The data also indicate that loss of calcium binding at site 1 adjusts the aberrant conformation of Tyr-138 produced by mutation of site 3 toward the wild-type structure. However, activation studies for skeletal muscle myosin light chain kinase (SK-MLCK) established that all of the multiple binding site mutants are poor activators of SK-MLCK. Thus, globally, the calcium-induced conformation of B13Q is not closer to wild type than that of either the site 1 or the site 3 mutant. The positioning of Tyr-138 within the crystal structure of calmodulin suggests that effects of the N-terminal lobe on this residue may be mediated via changes to the central linker region of the protein.

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“…Given the effects of electrolytes on the electrical measurements taken by a SiNW-FET, we generally used phosphate solution (0.1 × PS, consisting of 0.76 mM Na 2 HPO 4 and 0.24 mM NaH 2 PO 4 at pH 7.4) as a buffer in all of the sensing experiments, of which the corresponding Debye screening length (λ D ) is 6.1 nm. The electrical measurements under such a solution environment should effectively reflect the binding of interacting proteins to CaM-GST that was estimated to be ∼5.6 nm distant from the surface of the SiNW-FET (17,18). As shown in Fig.…”

Section: Supporting Information)mentioning

confidence: 99%

Label-free detection of protein-protein interactions using a calmodulin-modified nanowire transistor

Lin

Hsieh

Lin

et al. 2009

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

122

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In this study, we describe a highly sensitive and reusable silicon nanowire field-effect transistor for the detection of protein-protein interactions. This reusable device was made possible by the reversible association of glutathione S-transferase-tagged calmodulin with a glutathione modified transistor. The calmodulin-modified transistor exhibited selective electrical responses to Ca 2þ (≥1 μM) and purified cardiac troponin I (∼7 nM); the change in conductivity displayed a linear dependence on the concentration of troponin I in a range from 10 nM to 1 μM. These results are consistent with the previously reported concentration range in which the dissociation constant for the troponin I-calmodulin complex was determined. The minimum concentration of Ca 2þ required to activate calmodulin was determined to be 1 μM. We have also successfully demonstrated that the N-type Ca 2þ channels, expressed by cultured 293T cells, can be recognized specifically by the calmodulin-modified nanowire transistor. This sensitive nanowire transistor can serve as a high-throughput biosensor and can also substitute for immunoprecipitation methods used in the identification of interacting proteins.calcium ion | glutathione S-transfrease | N-type calcium channel | silicon nanowire field-effect transistor

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Calcium-induced increase in the radius of gyration and maximum dimension of calmodulin measured by small-angle x-ray scattering

Cited by 138 publications

References 18 publications

Binding of trifluoperazine to apocalmodulin revealed by a combination of small-angle X-ray scattering and nuclear magnetic resonance

Binding of trifluoperazine to apocalmodulin revealed by a combination of small-angle X-ray scattering and nuclear magnetic resonance

Interlobe communication in multiple calcium‐binding site mutants of Drosophila calmodulin

Label-free detection of protein-protein interactions using a calmodulin-modified nanowire transistor

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