title: Probing a coral genome for components of the  photoprotective scytonemin biosynthetic pathway and the 2-aminoethylphosphonate pathway.
abstract: Genome sequences of the reef-building coral, Acropora digitifera, have been decoded. Acropora inhabits an environment with intense ultraviolet exposure and hosts the photosynthetic endosymbiont, Symbiodinium. Acropora homologs of all four genes necessary for biosynthesis of the photoprotective cyanobacterial compound, shinorine, are present. Among metazoans, these genes are found only in anthozoans. To gain further evolutionary insights into biosynthesis of photoprotective compounds and associated coral proteins, we surveyed the Acropora genome for 18 clustered genes involved in cyanobacterial synthesis of the anti-UV compound, scytonemin, even though it had not previously been detected in corals. We identified candidates for only 6 of the 18 genes, including tyrP, scyA, and scyB. Therefore, it does not appear that Acropora digitifera can synthesize scytonemin independently. On the other hand, molecular phylogenetic analysis showed that one tyrosinase gene is an ortholog of vertebrate tyrosinase genes and that the coral homologs, scyA and scyB, are similar to bacterial metabolic genes, phosphonopyruvate (ppyr) decarboxylase and glutamate dehydrogenase (GDH), respectively. Further genomic searches for ppyr gene-related biosynthetic components indicate that the coral possesses a metabolic pathway similar to the bacterial 2-aminoethylphosphonate (AEP) biosynthetic pathway. The results suggest that de novo synthesis of carbon-phosphorus compounds is performed in corals.
authors: Marine Genomics Unit, Okinawa Institute of Science and Technology, Onna, Okinawa 904-0495, Japan. eiichi@oist.jp
authors: Eiichi
authors: E
authors: Shoguchi
authors: Makiko
authors: M
authors: Tanaka
authors: Takeshi
authors: T
authors: Takeuchi
authors: Chuya
authors: C
authors: Shinzato
authors: Nori
authors: N
authors: Satoh
mesh_terms: D000615:Aminoethylphosphonic Acid / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D037421:Anthozoa / Q000235:genetics*; D016208:Databases, Factual; D005786:Gene Expression Regulation; D016678:Genome; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*; D010802:Phylogeny
chemical_list: D007211:Indoles; D010636:Phenols; C083368:scytonemin; D000615:Aminoethylphosphonic Acid