Biosynthesis of the Methoxylated Carotenoids in Rhodospirillum rubrum

Abstract

Kinetic analysis of the carotenoid changes in resting cells of the photosynthetic bacLierium Rhlodospirillurn rubrum (6,13) have shown that the overall biosynthetic sequence of the bacterial carotenoids is: saturated precursors -> lycopene --P481 -> spirilloxanthin. Braithwaite and Goodwrin (2)

Carotenoid biosynthesis in Rhodopseudomonas spheroides. S-Adenosylmethionine as the methylating agent in the biosynthesis of spheroidene and spheroidenone

“…R. rubrum by incubation with methionine or S-adenosylmethionine has previously been reported (Benedict & Beckman, 1964;Beckman et al, 1965) but the carotenoids were not rigorously purified, and it was not conclusively established by degradation that the labelling was located in the methoxy groups. The degradation of spheroidene and spheroidenone labelled by incubation ofRps.…”

“…1973 thus confirming that the labelling in spheroidenone is located entirely in the methoxy group. The incorporation of methionine and S-adenosylmethionine into spirilloxanthin in R. rubrum has previously been established (Benedict & Beckman, 1964;Beckman et al, 1965); therefore it was reasonable to expect that these substrates would also be incorporated into other methoxycarotenoids in other bacteria. The present work is the first direct demonstration of the incorporation of methionine and Sadenosylmethionine into spheroidene and spheroidenone in Rps.…”