Spectral properties of LH2 exhibit very similar even when heterologously express LH2 with β-subunit fusion protein in Rhodobacter sphaeroides

Zhiping Zhao, Xin Nie, Zongli Hu, Guoping Chen, Zaixin Li, Zhi Zhang

Bioengineering College, Chongqing University, Chongqing, China.
School of Chemistry and Pharmaceutical Engineering, Sichuan University of Science & Engineering, Zigong, China.

DOI: 10.4236/abc.2013.31013                

Abstract

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.

Keywords

LH2; Spectral Property; FT-IR; Photopigment

Conflicts of Interest

The authors declare no conflicts of interest.

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