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Title: Structural plasticity of the Rhodobacter sphaeroides photosystem
Author: Crouch, Lucy I.
ISNI:       0000 0004 2724 462X
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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Purple bacteria are metabolically-fiexible organisms that have been used widely in the study of the fundamental processes of photosynthesis. These bacteria possess multi- component photosystems composed of a variety of pigment-proteins. In all characterized purple photosynthetic bacteria a reaction centre (RC), whose function is photochemical charge separation, is surrounded by an LH1 light harvesting pigment-protein to form a core RC-LH1 complex. In some species additional light harvesting is provided by one or more peripheral light harvesting pigment-proteins. In the best characterized purple photosynthetic bacterium, Rhodobacter sphaeroides, the RC-LH1 core complex is present in either a monomeric or dimeric form, in which either one or two RCs are surrounded by a C- or S-shaped LH1 antenna, respectively. One aim of the work described in this thesis was to carry out the first systematic analysis of how environmental (growth) conditions, changes in carotenoid composition and genetic manipulation (gene deletion and complementation in trans) affects the composition of the Rhodobacter sphaeroides photosystem, with particular focus on the compositions and relative amounts of the monomeric and dimeric forms of the RC-LH1 complex. The composition of the photosystem assembled in range of Rhodobacter species was also explored. Subsequent work focused on the influence of the LH1 and PufX components on the assembly of the dimeric form of the RC-LH1 complex. In addition, a series of site-directed mutagenesis of the PufX polypeptide was carried out to explore the roles of this protein in defining the aggregation state of the LH1 pigment-protein around the RC, enabling correct function of the RC-LH1 complex, and facilitating assembly of the dimeric form.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available