Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
The Phycomyces blakesleeanus wild-type is yellow, because it accumulates b-carotene as the main carotenoid. A new carotenoid mutant of this fungus (A486) was isolated, after treatment with ethyl methane sulfonate (EMS), showing a whitish coloration. It accumulates large amounts of phytoene, small quantities of phyto¯uene, f-carotene and neurosporene, in decreasing amounts, and traces of b-carotene. This phenotype indicates that it carries a leaky mutation a ecting the enzyme phytoene dehydrogenase (EC 1.3.-.-), which is speci®ed by the gene carB | Eur. J. Biochem. 269 902-908 2002 FEBS 2002 Interallelic complementation provides genetic evidence for the multimeric organization of the Phycomyces blakesleeanus phytoene dehydrogenase Catalina Sanz1 Maria I. Alvarez1 Margarita Orejas1 Antonio Velayos1 Arturo P. Eslava2 and Ernesto P. Benito2 Area de Genetica Departamento de Microbiologia y Genetica Universidad de Salamanca Edificio Departamental Avda Salamanca Spain 2Centro Hispano-Luso de Investigaciones Agrarias Universidad de Salamanca Edificio Departamental Avda Salamanca Spain The Phycomyces blakesleeanus wild-type is yellow because it accumulates b-carotene as the main carotenoid. A new carotenoid mutant of this fungus A486 was isolated after treatment with ethyl methane sulfonate EMS showing a whitish coloration. It accumulates large amounts of phytoene small quantities of phytofluene f-carotene and neuro-sporene in decreasing amounts and traces of b-carotene. This phenotype indicates that it carries a leaky mutation affecting the enzyme phytoene dehydrogenase EC 1.3.-.- which is specified by the gene carB. Biochemical analysis of heterokaryons showed that mutant A486 complements two previously characterized carB mutants C5 carB10 and S442 carB401 . Sequence analysis of the carB gene genomic copy from these three strains revealed that they are all altered in the gene carB giving information about the nature of the mutation in each carB mutant allele. The interallelic complementation provides evidence for the multimeric organization of the P. blakesleeanus phytoene dehydrogenase. Keywords carotenoid phytoene dehydrogenase interallelic complementation Phycomyces blakesleeanus. Carotenoids represent one of the most abundant and widely distributed classes of pigment in nature. They are present in photosynthetic bacteria cyanobacteria algae and higher plants as well as in nonphotosynthetic bacteria and fungi 1 . Carotenoids are colour pigments in flowers and fruits and also in many crustaceans insects fishes .
