Heterologous Production of the Photosynthetic Reaction Center and Light Harvesting 1 Complexes of the Thermophile Thermochromatium tepidum in the Mesophile Rhodobacter sphaeroides and Thermal Stability of a Hybrid Core Complex

被引:5
|
作者
Jun, D. [1 ]
Huang, V. [1 ]
Beatty, J. T. [1 ]
机构
[1] Univ British Columbia, Dept Microbiol & Immunol, Vancouver, BC, Canada
基金
加拿大自然科学与工程研究理事会;
关键词
photosynthesis; gene heterologous expression; thermophile; mesophile; R; sphaeroides; T; tepidum; core complex; reaction center; light harvesting; BACTERIAL REACTION CENTERS; ELECTRON-TRANSFER; PROTEIN; PURIFICATION; DIMERIZATION; MUTATIONS; MECHANISM; EVOLUTION; MUTANTS; CELLS;
D O I
10.1128/AEM.01481-17
中图分类号
Q81 [生物工程学(生物技术)]; Q93 [微生物学];
学科分类号
071005 ; 0836 ; 090102 ; 100705 ;
摘要
The photosynthetic complexes of the thermophile Thermochromatium tepidum are of considerable interest in biohybrid solar cell applications because of the ability of thermophilic proteins to tolerate elevated temperatures. Synthetic operons encoding reaction center (RC) and light harvesting 1 (LH1) pigment-protein complexes of T. tepidum were expressed in the mesophile Rhodobacter sphaeroides. The T. tepidum RC (TRC) was assembled and was found to be functional with the addition of menadione to populate the Q(A) pocket. The production of T. tepidum LH1 (TLH1) was increased by selection of a phototrophy-capable mutant after UV irradiation mutagenesis, which yielded a hybrid RC-TLH1 core complex consisting of the R. sphaeroides RC and T. tepidum TLH1, confirmed by the absorbance peak of TLH1 at 915 nm. Affinity chromatography partial purification and subsequent sucrose gradient analysis of the hybrid RC-TLH1 core complex indicated that this core complex assembled as a monomer. Furthermore, the RC-TLH1 hybrid core complex was more tolerant of a temperature of 70 degrees C than the R. sphaeroides RC-LH1 core complexes in both the dimeric and monomeric forms; after 1 h, the hybrid complex retained 58% of the initial starting value, compared to values of 11% and 53% for the R. sphaeroides RC-LH1 dimer and monomer forms, respectively. IMPORTANCE This work is important because it is a new approach to bioengineering of photosynthesis proteins for potential use in biophotovoltaic solar energy capture. The work establishes a proof of principle for future biohybrid solar cell applications.
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页数:15
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