Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 2016-05-05
Burakova, Ludmila P.
Natashin, Pavel V.
Liu, Zhi-Jie
Burakova, Ludmila P.
Natashin, Pavel V.
Malikova, Natalia P.
Vysotski, Eugene S.
Burakova, Ludmila P.
Natashin, Pavel V.
Niu, Fengfeng
Pu, Mengchen
Liu, Zhi-Jie
Liu, Zhi-Jie
Abstract： Light-sensitive photoprotein berovin accounts for a bright bioluminescence of ctenophore Beroe abyssicola. Berovin is functionally identical to the well-studied Ca2+-regulated photoproteins of jellyfish, however in contrast to those it is extremely sensitive to the visible light. Berovin contains three EF-hand Ca2+-binding sites and consequently belongs to a large family of the EF-hand Ca2+-binding proteins. Here we report the spatial structure of apo-berovin with bound Mg2+ determined at 1.75 A. The magnesium ion is found in each functional EF-hand loop of a photoprotein and coordinated by oxygen atoms donated by the side-chain groups of aspartate, carbonyl groups of the peptide backbone, or hydroxyl group of serine with characteristic oxygen-Mg2+ distances. As oxygen supplied by the side-chain of the twelfth residue of all Ca2+-binding loops participates in the magnesium ion coordination, it was suggested that Ca2+-binding loops of berovin belong to the mixed Ca2+/Mg2+ rather than Ca2+-specific type. In addition, we report an effect of physiological concentration of Mg2+ on bioluminescence of berovin (sensitivity to Ca2+, rapid-mixed kinetics, light-sensitivity, thermostability, and apo-berovin conversion into active protein). The different impact of physiological concentration of Mg2+ on berovin bioluminescence as compared to hydromedusan photoproteins was attributed to different affinities of the Ca2+-binding sites of these photoproteins to Mg2+. (C) 2015 Elsevier B.V. All rights reserved.
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