Analysis of the biosynthetic pathway for sulfoquinovosyldiacylglycerol in the purple bacterium R. sphaeroides
- MSU-DOE Plant Research Laboratory, East Lansing, MI (USA)
The membrane lipid sulfoquinovosyldiacylglycerol (SQD) can be found in all photosynthetically active membranes studied. In a green leaf, about 50% of the organic sulfur is bound in SQD. Therefore, this sulfolipid constitutes a major component of the global sulfur cycle. However, since the discovery of SQD, very little progress has been made towards the elucidation of the biosynthetic pathway. For a genetical analysis of the pathway of SQD, we selected the photosynthetic purple-nonsulfur bacterium R. sphaeroides, as our model system. We have been able to isolate several classes of mutants, which show reduced levels of SQD. Some of the mutants accumulate {sup 35}S-labeled, water soluble compounds. We expect that these compounds are related to precursors or are precursors, which accumulate due to a specific block in the biosynthetic pathway of SQD. To study the possible precursor function of these compounds, we developed an in vitro SQD biosynthesis system using cell free extracts from R. sphaeroides. In addition, we have been able to isolate cosmids prepared from WT DNA, which complement three classes of SQD mutants in R. sphaeroides. The analysis and expression of the genes encoded by these cosmids should facilitate the characterization of the proteins involved in SQD biosynthesis.
- OSTI ID:
- 5840919
- Report Number(s):
- CONF-9007196-; CODEN: PPYSA
- Journal Information:
- Plant Physiology, Supplement; (USA), Vol. 93:1; Conference: Annual meeting of the American Society of Plant Physiologists, Indianapolis, IN (USA), 29 Jul - 2 Aug 1990; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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