Structural evidence for non-canonical binding of Ca 2+ to a canonical EF-hand of a conventional myosin

Judit É Debreczeni, László Farkas, V. Harmat, C. Hetényi, István Hajdú, P. Závodszky, Kazuhiro Kohama, L. Nyitray

Research output: Contribution to journalArticle

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Abstract

We have previously identified a single inhibitory Ca 2+-binding site in the first EF-hand of the essential light chain of Physarum conventional myosin (Farkas, L., Malnasi-Csizmadia, A., Nakamura, A., Kohama, K., and Nyitray, L. (2003) J. Biol. Chem. 278, 27399-27405). As a general rule, conformation of the EF-hand-containing domains in the calmodulin family is "closed" in the absence and "open" in the presence of bound cations; a notable exception is the unusual Ca 2+-bound closed domain in the essential light chain of the Ca 2+-activated scallop muscle myosin. Here we have reported the 1.8 Å resolution structure of the regulatory domain (RD) of Physarum myosin II in which Ca 2+ is bound to a canonical EF-hand that is also in a closed state. The 12th position of the EF-hand loop, which normally provides a bidentate ligand for Ca 2+ in the open state, is too far in the structure to participate in coordination of the ion. The structure includes a second Ca 2+ that only mediates crystal contacts. To reveal the mechanism behind the regulatory effect of Ca 2+, we compared conformational flexibilities of the liganded and unliganded RD. Our working hypothesis, i.e. the modulatory effect of Ca 2+ on conformational flexibility of RD, is in line with the observed suppression of hydrogen-deuterium exchange rate in the Ca 2+-bound form, as well as with results of molecular dynamics calculations. Based on this evidence, we concluded that Ca 2+ -induced change in structural dynamics of RD is a major factor in Ca 2+-mediated regulation of Physarum myosin II activity.

Original languageEnglish
Pages (from-to)41458-41464
Number of pages7
JournalJournal of Biological Chemistry
Volume280
Issue number50
DOIs
Publication statusPublished - Dec 16 2005

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Myosin Type II
EF Hand Motifs
Physarum
Myosins
Deuterium
Structural dynamics
Calmodulin
Muscle
Conformations
Molecular dynamics
Cations
Hydrogen
Binding Sites
Pectinidae
Ions
Ligands
Light
Crystals
Molecular Dynamics Simulation
Muscles

ASJC Scopus subject areas

  • Biochemistry

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Structural evidence for non-canonical binding of Ca 2+ to a canonical EF-hand of a conventional myosin. / Debreczeni, Judit É; Farkas, László; Harmat, V.; Hetényi, C.; Hajdú, István; Závodszky, P.; Kohama, Kazuhiro; Nyitray, L.

In: Journal of Biological Chemistry, Vol. 280, No. 50, 16.12.2005, p. 41458-41464.

Research output: Contribution to journalArticle

Debreczeni, Judit É ; Farkas, László ; Harmat, V. ; Hetényi, C. ; Hajdú, István ; Závodszky, P. ; Kohama, Kazuhiro ; Nyitray, L. / Structural evidence for non-canonical binding of Ca 2+ to a canonical EF-hand of a conventional myosin. In: Journal of Biological Chemistry. 2005 ; Vol. 280, No. 50. pp. 41458-41464.
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T1 - Structural evidence for non-canonical binding of Ca 2+ to a canonical EF-hand of a conventional myosin

AU - Debreczeni, Judit É

AU - Farkas, László

AU - Harmat, V.

AU - Hetényi, C.

AU - Hajdú, István

AU - Závodszky, P.

AU - Kohama, Kazuhiro

AU - Nyitray, L.

PY - 2005/12/16

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AB - We have previously identified a single inhibitory Ca 2+-binding site in the first EF-hand of the essential light chain of Physarum conventional myosin (Farkas, L., Malnasi-Csizmadia, A., Nakamura, A., Kohama, K., and Nyitray, L. (2003) J. Biol. Chem. 278, 27399-27405). As a general rule, conformation of the EF-hand-containing domains in the calmodulin family is "closed" in the absence and "open" in the presence of bound cations; a notable exception is the unusual Ca 2+-bound closed domain in the essential light chain of the Ca 2+-activated scallop muscle myosin. Here we have reported the 1.8 Å resolution structure of the regulatory domain (RD) of Physarum myosin II in which Ca 2+ is bound to a canonical EF-hand that is also in a closed state. The 12th position of the EF-hand loop, which normally provides a bidentate ligand for Ca 2+ in the open state, is too far in the structure to participate in coordination of the ion. The structure includes a second Ca 2+ that only mediates crystal contacts. To reveal the mechanism behind the regulatory effect of Ca 2+, we compared conformational flexibilities of the liganded and unliganded RD. Our working hypothesis, i.e. the modulatory effect of Ca 2+ on conformational flexibility of RD, is in line with the observed suppression of hydrogen-deuterium exchange rate in the Ca 2+-bound form, as well as with results of molecular dynamics calculations. Based on this evidence, we concluded that Ca 2+ -induced change in structural dynamics of RD is a major factor in Ca 2+-mediated regulation of Physarum myosin II activity.

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