Abstract
Calbindin D28k is an intracellular Ca(2+)-binding protein containing six subdomains of EF-hand type. The number and identity of the globular domains within this protein have been elucidated using six synthetic peptide fragments, each corresponding to one EF-hand subdomain. All six peptides were mixed in equimolar amounts in the presence of 10 mM Ca2+ to allow for the reconstitution of domains. The mixture was compared to native calbindin D28k and to the sum of the properties of the individual peptides using circular dichroism (CD), fluorescence, and 1H NMR spectroscopy, as well as gel filtration and ion-exchange chromatography. It was anticipated that if the peptides associate to form native-like domains, the properties would be similar to those of the intact protein, whereas if they did not interact, they would be the same as the properties of the isolated peptides. The results show that the peptides in the mixture interact with one another. For example, the CD and fluorescence spectra for the mixture are very similar to those of the intact calbindin D28k, suggesting that the mixed EF-hand fragments associate to form a native-like structure. To determine the number of domains and the subdomain composition of each domain in calbindin D28k, a variety of peptide combinations containing two to five EF-hand fragments were studied. The spectral and chromatographic properties of all the mixtures containing less than six peptides were closer to the sum of the properties of the relevant individual peptides than to the mixture of the six peptides. The results strongly suggest that all six EF-hands are packed into one globular domain. The association of the peptide fragments is observed to drive the folding of the individual subdomains. For example, one of the fragments, EF2, which is largely unstructured in isolation even in the presence of high concentrations of Ca2+, is considerably more structured in the presence of the other peptides, as judged by CD difference spectroscopy. The CD data also suggest that the packing between the individual subdomains is specific.
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Selected References
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- Akerfeldt K. S., Coyne A. N., Wilk R. R., Thulin E., Linse S. Ca2+-binding stoichiometry of calbindin D28k as assessed by spectroscopic analyses of synthetic peptide fragments. Biochemistry. 1996 Mar 26;35(12):3662–3669. doi: 10.1021/bi9527956. [DOI] [PubMed] [Google Scholar]
- Andersson A., Forsén S., Thulin E., Vogel H. J. Cadmium-113 nuclear magnetic resonance studies of proteolytic fragments of calmodulin: assignment of strong and weak cation binding sites. Biochemistry. 1983 May 10;22(10):2309–2313. doi: 10.1021/bi00279a001. [DOI] [PubMed] [Google Scholar]
- Blanchard H., Grochulski P., Li Y., Arthur J. S., Davies P. L., Elce J. S., Cygler M. Structure of a calpain Ca(2+)-binding domain reveals a novel EF-hand and Ca(2+)-induced conformational changes. Nat Struct Biol. 1997 Jul;4(7):532–538. doi: 10.1038/nsb0797-532. [DOI] [PubMed] [Google Scholar]
- Durussel I., Luan-Rilliet Y., Petrova T., Takagi T., Cox J. A. Cation binding and conformation of tryptic fragments of Nereis sarcoplasmic calcium-binding protein: calcium-induced homo- and heterodimerization. Biochemistry. 1993 Mar 9;32(9):2394–2400. doi: 10.1021/bi00060a034. [DOI] [PubMed] [Google Scholar]
- Finn B. E., Evenäs J., Drakenberg T., Waltho J. P., Thulin E., Forsén S. Calcium-induced structural changes and domain autonomy in calmodulin. Nat Struct Biol. 1995 Sep;2(9):777–783. doi: 10.1038/nsb0995-777. [DOI] [PubMed] [Google Scholar]
- Finn B. E., Kördel J., Thulin E., Sellers P., Forsén S. Dissection of calbindin D9k into two Ca(2+)-binding subdomains by a combination of mutagenesis and chemical cleavage. FEBS Lett. 1992 Feb 24;298(2-3):211–214. doi: 10.1016/0014-5793(92)80059-p. [DOI] [PubMed] [Google Scholar]
- Gagné S. M., Tsuda S., Li M. X., Smillie L. B., Sykes B. D. Structures of the troponin C regulatory domains in the apo and calcium-saturated states. Nat Struct Biol. 1995 Sep;2(9):784–789. doi: 10.1038/nsb0995-784. [DOI] [PubMed] [Google Scholar]
- Griffith J. P., Kim J. L., Kim E. E., Sintchak M. D., Thomson J. A., Fitzgibbon M. J., Fleming M. A., Caron P. R., Hsiao K., Navia M. A. X-ray structure of calcineurin inhibited by the immunophilin-immunosuppressant FKBP12-FK506 complex. Cell. 1995 Aug 11;82(3):507–522. doi: 10.1016/0092-8674(95)90439-5. [DOI] [PubMed] [Google Scholar]
- Kretsinger R. H., Nockolds C. E. Carp muscle calcium-binding protein. II. Structure determination and general description. J Biol Chem. 1973 May 10;248(9):3313–3326. [PubMed] [Google Scholar]
- Li M. X., Chandra M., Pearlstone J. R., Racher K. I., Trigo-Gonzalez G., Borgford T., Kay C. M., Smillie L. B. Properties of isolated recombinant N and C domains of chicken troponin C. Biochemistry. 1994 Feb 1;33(4):917–925. doi: 10.1021/bi00170a010. [DOI] [PubMed] [Google Scholar]
- Lin G. D., Chattopadhyay D., Maki M., Wang K. K., Carson M., Jin L., Yuen P. W., Takano E., Hatanaka M., DeLucas L. J. Crystal structure of calcium bound domain VI of calpain at 1.9 A resolution and its role in enzyme assembly, regulation, and inhibitor binding. Nat Struct Biol. 1997 Jul;4(7):539–547. doi: 10.1038/nsb0797-539. [DOI] [PubMed] [Google Scholar]
- Linse S., Helmersson A., Forsén S. Calcium binding to calmodulin and its globular domains. J Biol Chem. 1991 May 5;266(13):8050–8054. [PubMed] [Google Scholar]
- Martin S. R., Andersson Teleman A., Bayley P. M., Drakenberg T., Forsen S. Kinetics of calcium dissociation from calmodulin and its tryptic fragments. A stopped-flow fluorescence study using Quin 2 reveals a two-domain structure. Eur J Biochem. 1985 Sep 16;151(3):543–550. doi: 10.1111/j.1432-1033.1985.tb09137.x. [DOI] [PubMed] [Google Scholar]
- Nakayama S., Moncrief N. D., Kretsinger R. H. Evolution of EF-hand calcium-modulated proteins. II. Domains of several subfamilies have diverse evolutionary histories. J Mol Evol. 1992 May;34(5):416–448. doi: 10.1007/BF00162998. [DOI] [PubMed] [Google Scholar]
- Permyakov E. A., Medvedkin V. N., Mitin Y. V., Kretsinger R. H. Noncovalent complex between domain AB and domains CD*EF of parvalbumin. Biochim Biophys Acta. 1991 Jan 8;1076(1):67–70. doi: 10.1016/0167-4838(91)90220-t. [DOI] [PubMed] [Google Scholar]
- Shaw G. S., Hodges R. S., Sykes B. D. Determination of the solution structure of a synthetic two-site calcium-binding homodimeric protein domain by NMR spectroscopy. Biochemistry. 1992 Oct 13;31(40):9572–9580. doi: 10.1021/bi00155a009. [DOI] [PubMed] [Google Scholar]
- Zhang M., Tanaka T., Ikura M. Calcium-induced conformational transition revealed by the solution structure of apo calmodulin. Nat Struct Biol. 1995 Sep;2(9):758–767. doi: 10.1038/nsb0995-758. [DOI] [PubMed] [Google Scholar]
