Structural characterization and comparison of antenna complexes of R26 and R26.1 mutants of Rhodopseudomonas sphaeroides

Robert, Bruno; Vermeglio, A.; Lutz, Marc

doi:10.1016/0005-2728(84)90239-1

Cited by 15 publications

(11 citation statements)

References 7 publications

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“…It is possible that small amounts of LH2 polypeptides are harmful in some way when carotenoids are absent; certainly the carotenoidless mutant R26 (Clayton and Smith, 1960) exhibits a tendency to revert to the strain R26. 1 containing a modified LH2 complex (Davidson and Cogdell, 1981;Robert et al, 1984). The nature of this modification partially compensates for the carotenoidless condition as shown by our recent studies on site-directed mutants of LH2 expressed in carotenoid-deficient backgrounds (G. J. S. Fowler, H. P. Lang and C. N. Hunter, unpublished work).…”

Section: Lh2mentioning

confidence: 78%

“…It is not so easy to establish whether or not these transcripts are translated, as complexes with a modified structure could exhibit an increased susceptibility to endogenous proteolytic attack. It appears that an LH2 complex can only assemble in carotenoidless mutants if there is some compensating alteration in the structure (Davidson and Cogdell, 1981;Robert et al, 1984), but past studies have yielded conflicting results on the relationship between LH2 assembly and carotenoid biosynthesis. Both Zsebo and Hearst (1984) and Giuliano et al (1988) concluded that, if biosynthesis of coloured carotenoids is blocked in R. capsulatus, the bacteriochlorophyll-binding LH2 aand fipolypeptides are synthesized, but the non-bacteriochlorophyllbinding y-subunit of the LH2 complex is absent.…”

Section: Discussionmentioning

confidence: 99%

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The relationship between carotenoid biosynthesis and the assembly of the light-harvesting LH2 complex in Rhodobacter sphaeroides

Lang

Hunter

1994

Biochemical Journal

130

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Coloured carotenoids play some undefined role in the assembly of a functional light-harvesting 2 (LH2) complex in photosynthetic bacteria. We have used a series of transposon Tn5 insertion mutants disrupted at various stages of the carotenoid-biosynthetic pathway, together with an LH2 deletion/insertion mutant, to investigate this effect in Rhodobacter sphaeroides. Mutants were initially characterized by low-temperature absorbance spectroscopy and ultrastructural analysis: Northern-blot analysis demonstrated normal pucBA transcripts for LH2 polypeptides in all the carotenoid mutants. Analysis of translation of the puc transcript and investigation of the fate of any resulting LH2 polypeptides by SDS/PAGE, Western-blot and pulse-chase experiments clearly demonstrated that, in the absence of coloured carotenoids, the LH2 alpha- and beta-polypeptides are synthesized but are rapidly turned over and do not become stably integrated into the membrane. Complementation of mutants with lesions in the crtB and crtI genes, encoding phytoene synthase and phytoene desaturase respectively, with the cloned R. sphaeroides crtI gene, resulted in restoration of carotenoid biosynthesis and stable assembly of the LH2 complex in the crtI mutant but not in the crtB mutant, despite the presence of the CrtI protein.

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Section: Lh2mentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

The relationship between carotenoid biosynthesis and the assembly of the light-harvesting LH2 complex in Rhodobacter sphaeroides

Lang

Hunter

1994

Biochemical Journal

130

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“…They demonstrated that this blue-shifted strain, designated R26.1, contained not only LH1 but also an altered LH2 complex, in which the B800 peak is absent. This explained earlier spectroscopic observations that R26.1 contains two types of antenna complex (for example, Rijgersberg et al, 1980) and this was confirmed by subsequent work (Robert et al, 1984). Theiler et al (1985) determined the amino acid sequence of the LH1 polypeptides from R26.1 and a comparison with the wild type LH1 revealed a which was proposed to weaken the heterodimer.…”

Section: R26 and R261supporting

confidence: 54%

Genetic Manipulation of the Antenna Complexes of Purple Bacteria

Hunter

Advances in Photosynthesis and Respiration

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“…Genetic studies and use of modern recombinant DNA technology together have contributed to understanding the physical properties and synthetic regulation of both LH I (B870) and LH II (B800-860) antennae during photosynthetic cell development (13,15,26,36,37,49,50). Results of physical studies suggest (35,36) that holochrome B870 is structurally and functionally homogeneous among different species.…”

mentioning

confidence: 99%

“…On the other hand, holochrome B800-860 appears to be different. Although the B800-860 pigment centers show similar light energy transfer reactions, the holochrome exhibits heterogeneous physical properties (6,36,37).…”

mentioning

confidence: 99%

Influence of pH, O2, and temperature on the absorption properties of the secondary light-harvesting antenna in members of the family Rhodospirillaceae

Uffen¹

1985

J Bacteriol

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In some Rhodospirilaceae, the primary light-harvesting (LH I) antenna absorbs near-infrared light around 870 nm, whereas LH II (holochrome B800-860) has a major absorption band between 850 and 860 nm (B860) and a minor absorbancy around 800 nm (B800). Results show that, unlike LH I, holochrome B800-860 (LH II) exhibits unstable light absorption properties in whole cells. This was observed in Rhodopseudomonas capsulata grown anaerobically in light in weakly buffered carbohydrate medium; cultures lost both carotenoid-dependent brown-yellow pigmentation and LH II absorbancy. The whole cell spectrophotometric changes were attributed to mild acid conditions generated during sugar metabolism. LH II absorbancy was also destroyed in both R. capsulata and Rhodopseudomonas gelatinosa when cultures growing at neutral pH were acidified to a pH value around 5.0 with HCI. In contrast, during the same tiume period of exposure to pH 5.0, only a 50% decrease in Rhodopseudomonas sphaeroides LHIIH B800 absorbancy was measured. At neutral pH, LH II absorbancy in suspensions of nongrowing Rhodopseadomonas spp. was, also sensitive to 02 exposure and to incubation at 30 to 40'C. During treatment with 02, the rate of LH II B800 absorption decrease in R. gelatinosa and R. sphaeroides was 60 and 40% per h, respectively, compared with their absorbancy maximum around 860 nm. Both 860-nm absorbancy and the total bacteriochlorophyll content of the cells remained unchanged. On the other hand, no significant decrease in B800 of LH II in R. capsulata occurred during 02 exposure, but a 20% absorption decay rate per h of B800 was observed in cells incubated anaerobically at 40°C. These B800 LH II spectral changes in Rhodopseudomonas spp. were prevekited by maintaining cells at neutral pH and at 10°C. The near-infrared absorption spectrum of Rhodospirillum ridbrum, which does not form LH II, was not significantly influenced by these different pH, aerobic, or temperature conditions.

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Structural characterization and comparison of antenna complexes of R26 and R26.1 mutants of Rhodopseudomonas sphaeroides

Cited by 15 publications

References 7 publications

The relationship between carotenoid biosynthesis and the assembly of the light-harvesting LH2 complex in Rhodobacter sphaeroides

The relationship between carotenoid biosynthesis and the assembly of the light-harvesting LH2 complex in Rhodobacter sphaeroides

Genetic Manipulation of the Antenna Complexes of Purple Bacteria

Influence of pH, O2, and temperature on the absorption properties of the secondary light-harvesting antenna in members of the family Rhodospirillaceae

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