2bl0
From Proteopedia
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'''PHYSARUM POLYCEPHALUM MYOSIN II REGULATORY DOMAIN''' | '''PHYSARUM POLYCEPHALUM MYOSIN II REGULATORY DOMAIN''' | ||
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[[Category: Harmat, V.]] | [[Category: Harmat, V.]] | ||
[[Category: Nyitray, L.]] | [[Category: Nyitray, L.]] | ||
| - | [[Category: | + | [[Category: Ef-hand]] |
| - | [[Category: | + | [[Category: Muscle protein]] |
| - | [[Category: | + | [[Category: Myosin]] |
| - | [[Category: | + | [[Category: Slime mould]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 20:26:10 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 17:26, 3 May 2008
PHYSARUM POLYCEPHALUM MYOSIN II REGULATORY DOMAIN
Overview
We have previously identified a single inhibitory Ca2+-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 Ca2+-bound closed domain in the essential light chain of the Ca2+-activated scallop muscle myosin. Here we have reported the 1.8 A resolution structure of the regulatory domain (RD) of Physarum myosin II in which Ca2+ 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 Ca2+ in the open state, is too far in the structure to participate in coordination of the ion. The structure includes a second Ca2+ that only mediates crystal contacts. To reveal the mechanism behind the regulatory effect of Ca2+, we compared conformational flexibilities of the liganded and unliganded RD. Our working hypothesis, i.e. the modulatory effect of Ca2+ on conformational flexibility of RD, is in line with the observed suppression of hydrogen-deuterium exchange rate in the Ca2+-bound form, as well as with results of molecular dynamics calculations. Based on this evidence, we concluded that Ca2+-induced change in structural dynamics of RD is a major factor in Ca2+-mediated regulation of Physarum myosin II activity.
About this Structure
2BL0 is a Protein complex structure of sequences from Physarum polycephalum. Full crystallographic information is available from OCA.
Reference
Structural evidence for non-canonical binding of Ca2+ to a canonical EF-hand of a conventional myosin., Debreczeni JE, Farkas L, Harmat V, Hetenyi C, Hajdu I, Zavodszky P, Kohama K, Nyitray L, J Biol Chem. 2005 Dec 16;280(50):41458-64. Epub 2005 Oct 13. PMID:16227209 Page seeded by OCA on Sat May 3 20:26:10 2008
