CAROTENOID BIOSYNTHESIS IN PHOTOSYNTHETIC BACTERIA - GENETIC-CHARACTERIZATION OF THE RHODOBACTER-CAPSULATUS CRTI PROTEIN

  • 5 August 1989
    • journal article
    • research article
    • Vol. 264  (22) , 13109-13113
Abstract
Carotenoids are photoprotective pigments present in many photosynthetic and nonphotosynthetic organisms. The desaturation of phytoene into phytofluene is an early step in the biosynthetic pathway that in the photosynthetic bacterium Rhodobacter capsulatus is mediated by the product of the crtI gene. Here we report the sequencer of this gene and the identification of CrtI as a membrane protein of approximate Mr 60,000. Mutant strains with 5-fold lower or 10-fold higher levels of CrtI with respect to wild type have only small differences in their carotenoid content, indicating that the cellular concentration of CrtI is not a limiting factor in carotenoid biosynthesis. However, a correlation was found between the levels of CrtI and the formation of a photosynthetic antenna system.