Crystallization of two integral membrane pigment–protein complexes from the purple‐sulfur bacterium <i>Chromatium purpuratum</i>

Kerfeld, Cheryl A.; Thornber, J. Philip; Yeates, T.O.

doi:10.1002/pro.5560020818

Cited by 2 publications

(1 citation statement)

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“…In addition, it will reveal how this organization of pigments and proteins confers the unusual spectroscopic properties of this complex. To this end, we have prepared crystals of the photosynthetic pigment-protein complexes of C. purpuratum for X-ray diffraction experiments (Kerfeld et al, 1993).…”

Section: Concluding Commentmentioning

confidence: 99%

Purification and characterization of the peripheral antenna of the purple-sulfur bacterium Chromatium purpuratum: Evidence of an unusual pigment-protein composition

Yeates²,

Jp³

1994

Biochemistry

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The purification and characterization of the peripheral antenna and the preliminary characterization of a carotenoid-protein complex from the purple-sulfur bacterium Chromatium purpuratum are described. The peripheral antenna of C. purpuratum is unusual among purple bacteria in that it can be resolved by SDS-PAGE into six subunits, the largest number observed thus far for a spectrally pure antenna complex. N-terminal sequence analyses of these subunits suggest that they may have an additional bacteriochlorophyll-binding site located outside the transmembrane domain. The results of pigment-protein quantification are also consistent with additional pigment-binding sites in the C. purpuratum LH2. Furthermore, CD measurements and sequence analysis suggest the presence of considerable beta-type in addition to alpha-helical secondary structure. Thus, the secondary and quaternary structures of this complex differ significantly from light-harvesting complexes of other purple photosynthetic bacteria. A carotenoid-protein complex is also described; it is an apparent association of three proteins and carotenoid and is closely associated with the peripheral antenna. The purple-sulfur bacteria are evolutionarily older than the relatively better characterized purple-nonsulfur organisms. The phenotypic features described here of the C. purpuratum photosynthetic apparatus are related to those of other purple bacteria and green-sulfur bacteria and may reflect the evolutionary position of this organism.

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Section: Concluding Commentmentioning

confidence: 99%