title: Spontaneous and reversible high-frequency frameshifts originating a phase transition in the carotenoid biosynthesis pathway of the phototrophic bacterium Rhodobacter sphaeroides 2.4.1.
abstract: The synthesis of carotenoids in strain 2.4.1 of the phototrophic bacterium Rhodobacter sphaeroides is spontaneously turned on and off at a high frequency (10(-5) per cell per generation) giving rise alternatively to red (wild type) and green (mutant) clones. The crtD gene is not functional in green mutants as a consequence of the spontaneous addition of a guanosine in a stretch of seven guanosines located in the 5'-terminal coding region of this gene originating a frameshift. All spontaneous wild-type revertants isolated from green mutants had recovered the crtD gene function by loss of one of these reiterated guanosines. The transition Crt(+)----Crt(-)----Crt+, is strain-dependent, since Crt+ clones were not detected in ethyl methane sulphonate (EMS)-induced CrtD- mutants of two other strains of R. sphaeroides (WS22 and RS630) which harbour a recombinant plasmid containing the crtD gene from a spontaneous CrtD- mutant of strain 2.4.1 of R. sphaeroides.
authors.affiliation: Department of Genetics and Microbiology, Faculty of Sciences, Autonomous University of Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Garí
authors.forename: I
authors.initials: I
authors.lastname: Gibert
authors.forename: J
authors.initials: J
authors.lastname: Barbé
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002338:Carotenoids / Q000096:biosynthesis / Q000235:genetics*; D016368:Frameshift Mutation; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D012242:Rhodobacter sphaeroides / Q000235:genetics*
chemical_list: D002338:Carotenoids