title: Characterization of the proteinaceous skeletal organic matrix from the precious coral Corallium konojoi.
abstract: The Japanese red and pink corals are known to be precious because of their commercial value resulting from their use in ornaments, jewelry, and medicine. Precious corals are very interesting models for biomineralization studies and possess two different skeletal structures: an axial skeleton and an endoskeleton (sclerites). Although it has long been known that the organic matrix proteins existing in coral skeletons are critical for the oriented precipitation of CaCO3 crystals, these proteins in moderate deep-sea Japanese precious corals remain uncharacterized. Therefore, in this study, we performed skeletal whole proteome analyses using 1D and 2D electrophoresis, nano-LC, and MALDI-TOF-TOF MS. We identified a total of 147 functional coral skeletal organic matrix proteins (120 from the sclerites and 36 from the axial skeleton), including two calcium-binding calmodulin. Among the organic matrix proteins identified, nine key proteins are highly typical and common in both skeletons. Strong glycosylation activity, which is essential for skeletal formation in calcifying organisms, was detected in both skeletons. This work demonstrates unique biomineralization-related proteins in precious corals and provides the first description of the major proteinaceous components of CaCO3 minerals in precious corals, enabling the comparative investigation of biocalcification in other octocorals.
authors.affiliation: Department of Chemical and Physical Sciences, University of Toronto, Toronto, Canada; Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, Munich, Germany; Department of Chemistry, Faculty of Science, University of the Ryukyus, Okinawa, Japan.
authors.forename: M Azizur
authors.initials: MA
authors.lastname: Rahman
authors.forename: Kristian
authors.initials: K
authors.lastname: Karl
authors.forename: Masanori
authors.initials: M
authors.lastname: Nonaka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujimura
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Shinjo
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Oomori
authors.forename: Gert
authors.initials: G
authors.lastname: Wörheide
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry* / Q000166:cytology* / Q000502:physiology; D002113:Calcification, Physiologic; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D020543:Proteome / Q000032:analysis* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D020543:Proteome; D002119:Calcium Carbonate
keywords: Animal proteomics; Biomineralization; Jewelry corals; Organic matrix proteins; Precious coral; Sclerites