title: Differential expression of the demosponge (Suberites domuncula) carotenoid oxygenases in response to light: protection mechanism against the self-produced toxic protein (Suberitine).
abstract: 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 β-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 β-carotene and Suberitine can be ascribed to a reversible energy transfer reaction. The enzyme that synthesises retinal in the sponge system is the β,β-carotene-15,15'-dioxygenase [carotene dioxygenase]. In order to clarify if this enzyme is the only β-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 β-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 β-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 β-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.
authors.affiliation: ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz D-55128, Germany.
authors.forename: Werner E G
authors.initials: WEG
authors.lastname: Müller
authors.affiliation: ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz D-55128, Germany.|National Research Center for Geoanalysis, 26 Baiwanzhuang Dajie, Beijing 100037, China.
authors.forename: Xiaohong
authors.identifier: 0000-0003-1796-6314
authors.initials: X
authors.lastname: Wang
authors.affiliation: ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz D-55128, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Binder
authors.affiliation: Department of Pharmacology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44160, USA.
authors.forename: Johannes von
authors.initials: JV
authors.lastname: Lintig
authors.affiliation: ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz D-55128, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wiens
authors.affiliation: ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz D-55128, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000201:enzymology; D003001:Cloning, Molecular; D008027:Light; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000633:toxicity; D012172:Retinaldehyde / Q000502:physiology; D047233:Suberites / Q000378:metabolism*
chemical_list: D011506:Proteins; C031284:suberitine protein, Suberites domuncula; D010105:Oxygenases; C500451:carotenoid oxygenase; D012172:Retinaldehyde