Whj. Westerhuis et al., ALTERED SPECTRAL PROPERTIES OF THE B875 LIGHT-HARVESTING PIGMENT-PROTEIN COMPLEX IN A RHODOBACTER-SPHAEROIDES MUTANT LACKING PUFX, Photochemistry and photobiology, 58(3), 1993, pp. 460-463
Mutants of Rhodobacter sphaeroides lacking the pufX gene are unable to
grow photosynthetically and have been reported to show impaired cycli
c electron flow and elevated B875 levels when grown at low oxygen tens
ion. An examination of the low-temperature optical properties of chrom
atophores from a pufX- strain, obtained by complementation of a pufLMX
- mutant in trans with pufQBALM, encoding polypeptides of the B875 ant
enna and reaction center complexes, revealed that the absorption and f
luorescence emission maxima and the fluorescence polarization rise ove
r the B875-Q, band were shifted to lower energies. These results sugge
st that the pufX gene product may limit the aggregation state of the B
875 complex, assuring the proper functional arrangement of antenna and
reaction center components within the cores of the photosynthetic uni
ts.