Spontaneous and reversible high-frequency frameshifts originating a phase transition in the carotenoid biosynthesis pathway of the phototrophic bacterium Rhodobacter sphaeroides 2.4.1
✍ Scribed by Garí, Eloi ;Gibert, Isidre ;Barbé, Jordi
- Book ID
- 104711987
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 910 KB
- Volume
- 232
- Category
- Article
- ISSN
- 0026-8925
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✦ Synopsis
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.