title: Homogentisate phytyltransferase from the unicellular green alga Chlamydomonas reinhardtii.
abstract: Homogentisate phytyltransferase (HPT) (EC 2.5.1.-) catalyzes the first committed step of tocopherol biosynthesis in all photosynthetic organisms. This paper presents the molecular characterization and expression analysis of HPT1 gene, and a study on the accumulation of tocopherols under different environmental conditions in the unicellular green alga Chlamydomonas reinhardtii. The Chlamydomonas HPT1 protein conserves all the prenylphosphate- and divalent cation-binding sites that are found in polyprenyltransferases and all the amino acids that are essential for its catalytic activity. Its hydrophobicity profile confirms that HPT is a membrane-bound protein. Chlamydomonas genomic DNA analysis suggests that HPT is encoded by a single gene, HPT1, whose promoter region contains multiple motifs related to regulation by jasmonate, abscisic acid, low temperature and light, and an ATCTA motif presents in genes involved in tocopherol biosynthesis and some photosynthesis-related genes. Expression analysis revealed that HPT1 is strongly regulated by dark and low-temperature. Under the same treatments, α-tocopherol increased in cultures exposed to darkness or heat, whereas γ-tocopherol did it in low temperature. The regulatory expression pattern of HPT1 and the changes of tocopherol abundance support the idea that different tocopherols play specific functions, and suggest a role for γ-tocopherol in the adaptation to growth under low-temperature.
authors.affiliation: Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain. Electronic address: b32gavag@uco.es.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Gálvez-Valdivieso
authors.affiliation: Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Cardeñosa
authors.affiliation: Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Pineda
authors.affiliation: Departamento de Botánica, Ecología y Fisiología Vegetal, Instituto Andaluz de Biotecnología and Campus Agroalimentario de Excelencia Internacional ceiA3, Campus de Rabanales, Edif. C-4, 3ª Planta, Universidad de Córdoba, 14071 Córdoba, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Aguilar
mesh_terms: D020418:Algal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D016415:Sequence Alignment
chemical_list: D020418:Algal Proteins; D019883:Alkyl and Aryl Transferases
keywords: Chlamydomonas reinhardtii; Low temperature acclimation; α-Tocopherol; γ-Tocopherol