tailieunhanh - Báo cáo khoa học: It’s cheap to be colorful Anthozoans show a slow turnover of GFP-like proteins

Pigments homologous to the green fluorescent protein (GFP) contribute up to 14% of the soluble protein content of many anthozoans. Maintenance of such high tissue levels poses a severe energetic penalty to the animals if protein turnover is fast. To address this as yet unexplored issue, we estab-lished that the irreversible green-to-red conversion of the GFP-like pig- | ễFEBS Journal It s cheap to be colorful Anthozoans show a slow turnover of GFP-like proteins Alexandra Leutenegger1 Cecilia D Angelo1 Mikhail V. Matz2 Andrea Denzel1 Franz Oswald3 Anya Salih4 G. Ulrich Nienhaus5 6 and Jorg Wiedenmann1 1 Institute of GeneralZoology and Endocrinology University of Ulm Germany 2 Integrative Biology University of Texas in Austin TX USA 3 Department of InternalMedicine I University of Ulm Germany 4 Electronic Microscopy Unit University of Sydney Australia 5 Institute of Biophysics University of Ulm Germany 6 Department of Physics University of Illinois at Urbana-Champaign IL USA Keywords coral pigments green fluorescent protein photoconversion protein half-life protein metabolism Correspondence J. Wiedenmann Institute of General Zoology and Endocrinology University of Ulm Albert Einstein-Allee 11 89069 Ulm Germany Fax 49 731 502 2581 Tel 49 731 502 2591 2584 E-mail These authors contributed equally to this work Received 17 February 2007 revised 10 March 2007 accepted 12 March 2007 Pigments homologous to the green fluorescent protein GFP contribute up to 14 of the soluble protein content of many anthozoans. Maintenance of such high tissue levels poses a severe energetic penalty to the animals if protein turnover is fast. To address this as yet unexplored issue we established that the irreversible green-to-red conversion of the GFP-like pigments from the reef corals Montastrea cavernosa mcavRFP and Lobophyllia hemprichii EosFP is driven by violet-blue radiation in vivo and in situ. In the absence of photoconverting light we subsequently tracked degradation of the red-converted forms of the two proteins in coral tissue using in vivo spectroscopy and immunochemical detection of the post-translational peptide backbone modification. The pigments displayed surprisingly slow decay rates characterized by half-lives of 20 days. The slow turnover of GFP-like proteins implies that the associated energetic costs for being