1sl7
From Proteopedia
Crystal structure of calcium-loaded apo-obelin from Obelia longissima
Overview
The crystal structures of calcium-loaded apo-aequorin and apo-obelin have been determined at resolutions 1.7A and 2.2 A, respectively. A calcium ion is observed in each of the three EF-hand loops that have the canonical calcium-binding sequence, and each is coordinated in the characteristic pentagonal bipyramidal configuration. The calcium-loaded apo-protein retain the same compact scaffold and overall fold as the unreacted photoproteins containing the bound substrate, 2-hyroperoxycoelenterazine, and also the same as the Ca2+-discharged obelin bound with product, coleneteramide. Nevertheless, there are easily discerned shifts in both helix and loop regions, and the shifts are not the same between the two proteins. It is suggested that these photoproteins to sense Ca2+ concentration transients and to produce their bioluminescence response on the millisecond timescale. A mechanism of intrastructural transmission of the calcium signal is proposed.
About this Structure
1SL7 is a Single protein structure of sequence from Obelia longissima. Full crystallographic information is available from OCA.
Reference
All three Ca2+-binding loops of photoproteins bind calcium ions: the crystal structures of calcium-loaded apo-aequorin and apo-obelin., Deng L, Vysotski ES, Markova SV, Liu ZJ, Lee J, Rose J, Wang BC, Protein Sci. 2005 Mar;14(3):663-75. Epub 2005 Feb 2. PMID:15689515 Page seeded by OCA on Sat May 3 08:50:33 2008
Categories: Obelia longissima | Single protein | Deng, L. | Lee, J. | Liu, Z J. | Markova, S V. | Rose, J. | SECSG, Southeast Collaboratory for Structural Genomics. | Vysotski, E S. | Wang, B C. | Aequorin | Bioluminescence | Calcium binding | Ef-hand | Fluorescence | Obelin | Photoprotein | Protein structure initiative | Psi | Secsg | Southeast collaboratory for structural genomic | Structural genomic
