Effect of Light and Oxygen and Adaptation to Changing Light Conditions in a Photosynthetic Mutant in Which the LHII Complex of Rhv. sulfidophilum Was Heterologously Expressed in a Strain of Rb. capsulatus Whose puc Operon Was Deleted
| Autor: | Norma L. Pucheu, María del Rosario Barbieri, Monier H. Tadros, Norma L. Kerber, Augusto F. García |
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| Rok vydání: | 2002 |
| Předmět: |
Light
Cell division Operon Photosynthetic Reaction Center Complex Proteins Mutant Light-Harvesting Protein Complexes Gene Expression Heterologous Biology Photosynthesis Applied Microbiology and Biotechnology Microbiology Rhodobacter capsulatus Bacterial Proteins Gene expression Phosphorylation Alphaproteobacteria Expression vector Strain (chemistry) Photosystem II Protein Complex General Medicine Adaptation Physiological Recombinant Proteins Oxygen Biochemistry Genes Bacterial Mutation Gene Deletion |
| Zdroj: | Current Microbiology. 45:209-216 |
| ISSN: | 1432-0991 0343-8651 |
| DOI: | 10.1007/s00284-001-0104-7 |
| Popis: | In this paper we show the effect of oxygen and light on the expression of the photosynthetic apparatus of a mutant heterologously expressing the puc operon. This mutant was obtained by introducing in trans an expression plasmid, bearing the puc A, B, and C genes of Rhv. sulfidophilum, as well as its own promoter, in an LHII(-) mutant of Rb. capsulatus. The results showed that oxygen and light repressed LHII expression. Even low-light intensities lowered the LHII content to undetectable levels by spectrophotometry or by SDS-PAGE. In high-light grown cells, where the relative ratios of LHI and LHII complexes were significantly diminished, we were able to detect LHII complexes. Under the latter condition, the absorption spectrum showed that some pigment accumulated in the membrane even in the absence of cell division. These pigments were used in a later step to assemble LHII complexes, when the high-light grown cells were transferred to semiaerobiosis in the dark. Transition of high-light grown cells to low-light conditions allowed us to study the adaptability of these heterologous mutant cells. We observed that adaptation never occurred, in part probably owing to energy limitation. |
| Databáze: | OpenAIRE |
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