Interactions between the light-harvesting subunits
and the non-covalently bound photopigments attribute considerably to the
spectral properties of photosynthetic bacteria light-harvesting complexes. In
our previous studies, we have constructed a novel Rhodobacter sphaeroides expression system. In the present study,
we focus on the spectral properties of LH2 when heterologously express LH2 with β-subunit- GFP fusion protein in Rb. sphaeroides. Near infra-red
spectrum of LH2 remained nearly unchanged as measured by spectroscopy.
Fluorescence spectrum suggested that the LH2 with β-subunit-GFP fusion protein complexes still possessed normal
activity in energy transfer. However, photopigments contents were
significantly decreased to a very low level in the LH2
with β-subunit-GFP fusion protein
complexes compared to that of LH2. FT-IR spectra indicated that interactions
between photopigments and LH2 α/β- subunits appeared not to be changed.
It was concluded that the LH2 spectral properties exhibited very similar even
when heterologously expressed LH2 b-subunit
fusion protein in Rb. sphaeroides.
Our present study may supply a new insight into better understand the interactions
between light-harvesting subunits and photopigments and bacterial photosynthesis
and promote the development of the novel Rb.
sphaeroides expression system.