Study Of Purple Photosynthetic Bacteria Lhi PufBA Mutants

Thermochromatium tepidum photosynthesis consists of unit capture photopigment protein complex, the LHI(light-harvesting I), the LHII(light-harvesting II)and the RC(Reaction Center). Study found that Tch.tepidum LHI-Qy characteristic absorption peak at915nm but other photosynthetic bacteria about880nm, in terms of long-wavelength, which had been happend35nm redshift, and the redshift reasons are unclear.In this study, we use molecular biology and spectral analysis method, cloning Tch.tepidum pufBA sequence in vitro, and for it alanine fixed point mutation, the mutant of pufBA sequence is built on the recombinant expression plasmid pRK404(including Rhodobacter sphaeroide pufQ, pufK, pufL, pufM, pufX), by transconjugant the expression plasmid was transfered into RbsAQ-X (Rb.sphaeroides deletion of genome pufQ-X), then optimizing the transconjugants’best culture conditions and Tetracycline resistance concentration, at last analyzing its expression characteristics.The results show that the mutant of Tch.tepidum pufBA in Rb.sphaeroides can express normally, but its protein expression quantity are low; spectral absorption show that the bacteria liquid of transconjugants have a characteristic absorption peak near the896nm; the best Tetracycline resistance concentration of transconjugants is20μg/mL, and better condition of culture is24℃,90rpm, facultative anaerobic, weak light. At present, we are still exploring the transconjugants’best condition of culture in the further step. Tch. tepidum LHI heterologous protein normal expression are helpful to the crystal structure of the research, but also for multiple locus mutation other functional protein in vitro provides some experimental datas.