Genetic Manipulation of the Antenna Complexes of Purple Bacteria

Hunter, C. Neil

doi:10.1007/0-306-47954-0_22

Cited by 15 publications

(16 citation statements)

References 152 publications

(123 reference statements)

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“…rubrum chromatophores, with the exception of a small (5 nm) difference in the peak position of the B880 antenna transition (for a discussion of the spectral properties of Rb. sphaeroides in which the B800-850 antenna genes have been deleted, see Hunter 1995). Comparing the relative intensity of the near infrared RC transition at 800 nm to the B880 antenna transition near 880 nm in the various strains used, it appears that the number of antenna Bchl molecules per RC is essentially the same in the wild type and mutant Rb.…”

Section: Experimental Methodsmentioning

confidence: 99%

Energy trapping and detrapping by wild type and mutant reaction centers of purple non-sulfur bacteria

et al. 1996

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Time-correlated single photon counting was used to study energy trapping and detrapping kinetics at 295 K in Rhodobacter sphaeroides chromatophore membranes containing mutant reaction centers. The mutant reaction centers were expressed in a background strain of Rb. sphaeroides which contained only B880 antenna complexes and no B800-850 antenna complexes. The excited state decay times in the isolated reaction centers from these strains were previously shown to vary by roughly 15-fold, from 3.4 to 52 ps, due to differences in the charge separation rates in the different mutants (Allen and Williams (1995) J Bioenerg Biomembr 27: 275-283). In this study, measurements were also performed on wild type Rhodospirillum rubrum and Rb. sphaeroides B880 antenna-only mutant chromatophores for comparison. The emission kinetics in membranes containing mutant reaction centers was complex. The experimental data were analyzed in terms of a kinetic model that involved fast excitation migration between antenna complexes followed by reversible energy transfer to the reaction center and charge separation. Three emission time constants were identified by fitting the data to a sum of exponential decay components. They were assigned to trapping/quenching of antenna excitations by the reaction center, recombination of the P(+)H(-) charge-separated state of the reaction center reforming an emitting state, and emission from uncoupled antenna pigment-protein complexes. The first varied from 60 to 160 ps, depending on the reaction center mutation; the second was 200-300 ps, and the third was about 700 ps. The observed weak linear dependence of the trapping time on the primary charge separation time, together with the known sub-picosecond exciton migration time within the antenna, supports the concept that it is energy transfer from the antenna to the reaction center, rather than charge separation, that limits the overall energy trapping time in wild type chromatophores. The component due to charge recombination reforming the excited state is minor in wild type membranes, but increases substantially in mutants due to the decreasing free energy gap between the states P(*) and P(+)H(-).

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Section: Experimental Methodsmentioning

confidence: 99%

Energy trapping and detrapping by wild type and mutant reaction centers of purple non-sulfur bacteria

et al. 1996

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“…For example, a cyanobacterial mutant lacking detectable phycobiliproteins was still capable of photoautotrophic growth [23], and many mutants lacking various light-harvesting proteins in purple bacteria have been described [24]. Foidl et al The blot shown in panel B was probed with a 0.5-kb HinfI fragment speci¢c for the csmC gene.…”

Section: Resultsmentioning

confidence: 99%

Insertional inactivation studies of the csmA and csmC genes of the green sulfur bacterium Chlorobium vibrioforme 8327: the chlorosome protein CsmA is required for viability but CsmC is dispensable

Chung¹

1998

FEMS Microbiology Letters

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“…RC) in purple non-sulphur photosynthetic bacteria (Bartley and Scolnik 1989;Cohen-Bazire and Stanier 1958;Hunter 1995;Lang et al 1994;Lang and Hunter 1994). This has been interpreted assuming that the stability of LH2 requires the presence of Cars.…”

Section: Lh2 Complexesmentioning

confidence: 99%

“…Cohen-Bazire and Stanier 1958;Goodwin and Osman 1953;Griffiths et al 1955;Griffiths and Stanier 1956;Hunter 1995;Lang et al 1995;Lang and Hunter 1994;Malhorta et al 1970;Moskalenko et al 1983;Moskalenko et al 1997). The use of mutagenesis makes it possible to interrupt the Car biosynthesis at any step and even to obtain mutants without any mature (coloured) carotenoids (so-called Car-less mutants) simultaneously with accumulation of the same amount of precursors or mutants with over-accumulation of intermediates (Hunter 1995;Lang et al 1995;Lang and Hunter 1994). For example, in strain G1C of Rhodobacter sphaeroides the carotenoids content in LH2 is 98% neurosporene and 2% lycopene (Gall et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity of carotenoid content and composition in LH2 of the purple sulphur bacterium Allochromatium minutissimum grown under carotenoid-biosynthesis inhibition

2008

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The effects brought about by growing Allochromatium (Alc.) minutissimum in the presence of different concentrations of the carotenoid (Car) biosynthetic inhibitor diphenylamine (DPA) have been investigated. A decrease of Car content (from approximately 70% to >5%) in the membranes was accompanied by an increase of the percentage of (immature) Cars with reduced numbers of conjugated C=C bonds (from neurosporene to phytoene). Based on the obtained results and the analysis of literature data, the conclusion is reached that accumulation of phytoene during inhibition did not occur. Surprisingly, DPA inhibited phytoene synthase instead of phytoene desaturase as generally assumed. The distribution of Cars in peripheral antenna (LH2) complexes and their effect on the stability of LH2 has been investigated using absorption spectroscopy and HPLC analysis. Heterogeneity of Car composition and contents in the LH2 pool is revealed. The Car contents in LH2 varied widely from control levels to complete absence. According to common view, the assembly of LH2 occurs only in the presence of Cars. Here, we show that the LH2 can be assembled without any Cars. The presence of Cars, however, is important for structural stability of LH2 complexes.

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Genetic Manipulation of the Antenna Complexes of Purple Bacteria

Cited by 15 publications

References 152 publications

Energy trapping and detrapping by wild type and mutant reaction centers of purple non-sulfur bacteria

Energy trapping and detrapping by wild type and mutant reaction centers of purple non-sulfur bacteria

Insertional inactivation studies of the csmA and csmC genes of the green sulfur bacterium Chlorobium vibrioforme 8327: the chlorosome protein CsmA is required for viability but CsmC is dispensable

Heterogeneity of carotenoid content and composition in LH2 of the purple sulphur bacterium Allochromatium minutissimum grown under carotenoid-biosynthesis inhibition

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