Differential Expression of the Demosponge (Suberites domuncula) Carotenoid Oxygenases in Response to Light: Protection Mechanism Against the Self-Produced Toxic Protein (Suberitine)

作者：Mueller, Werner E. G.; Wang, Xiaohong; Binder, Michael; von Lintig, Johannes; Wiens, Matthias; Schroeder, Heinz C.

来源：Marine Drugs, 2012, 10(1): 177-199.

DOI：10.3390/md10010177

• Suberitine
• beta-carotene
• retinal
• beta-carotene dioxygenase
• sponges
• Suberites domuncula

The demosponge Suberites domuncula has been described to contain high levels of a proteinaceous toxin, Suberitine, that displays haemolytic activityIn the present study this 7-8 kDa polypeptide has been isolated and was shown to exhibit also cytotoxic effects on cells of the same species. Addition of retinal, a recently identified metabolite of beta-carotene that is abundantly present in S. domuncula was found to reduce both the haemolytic and the cell toxic activity of Suberitine at a molar ratio of 1:1. Spectroscopic analyses revealed that the interaction between beta-carotene and Suberitine can be ascribed to a reversible energy transfer reaction. The enzyme that synthesises retinal in the sponge system is the beta,beta-carotene-15,15'-dioxygenase [carotene dioxygenase]. In order to clarify if this enzyme is the only beta-carotene-metabolizing enzyme a further oxygenase had been identified and cloned, the (related) carotenoid oxygenase. In contrast to the dioxygenase, the carotenoid oxygenase could not degrade beta-carotene or lycopene in Escherichia coli strains that produced these two carotenoids; therefore it had been termed related-carotenoid oxygenase. Exposure of primmorphs to light of different wavelengths from the visible spectrum resulted after 3 days in a strong upregulation of the dioxygenase in those 3D-cell aggregates that had been incubated with beta-carotene. The strongest effect is seen with blue light at a maximum around 490 nm. It is concluded that the toxin Suberitine is non-covalently modified by retinal, the cleavage product from beta-carotene via the enzyme carotene dioxygenase, a light inducible oxygenase. Hence, this study highlights that in S. domuncula the bioactive metabolite, retinal, has the property to detoxify its homologous toxin.

• 出版日期2012-1
• 单位国家地质实验测试中心