%0 Journal Article
%T Acquirement and characterization of a carotenoid mutant (GM309) of Rhodobacter sphaeroides 601
%A Yuan Liu
%A Wei Zhang
%A Yongqiang Wu
%A Chunhe Xu
%J Science China Life Sciences
%@ 1869-1889
%D 2004
%I 
%R 10.1360/02yc0254
%X A green mutant was obtained among the chemically induced mutants of Rhodobacter sphaeroides 601 (RS601) and named GM309. A blue shift of 20 nm of the carotenoid absorption spectrum was found in the light-harvesting complex II (LH2) of GM309. Different from LH2 of RS601, it was found that the carotenoids in GM309-LH2 changed to be neurosporene by mutation. Neurosporene lacks a conjugate double bond, compared with the spheroidene in RS601-LH2 which has ten conjugate double bonds. As shown by absorption and circular dichroism spectroscopy, the overall structure of GM309-LH2 is little affected by this change. From fluorescence emission spectra, it is found that GM309-LH2 can transfer energy from carotenoids to Bchl-B850 without any change in efficiency. But the efficiency of energy transfer from B800 to B850 in GM309-LH2 is decreased to be 42% of that of the native. This work would provide a novel method to investigate the mechanism of excitation energy transfer in LH2.
%K light-harvesting complex
%K carotenoid
%K excitation energy transfer
%K fluorescence
%U http://link.springer.com/article/10.1360/02yc0254