Characterization and localization of phosphatidyl-glycerophosphate and phosphatidylserine synthases in Rhodobacter sphaeroides

Catalytic properties and membrane associations of the phosphatidyl-glycerophosphate (PGP) and phosphatidylserine (PS) synthases of Rhodobacter sphaeroides were examined to further characterize sites of phospholipid biosynthesis. In preparations of cytoplasmic membrane (CM) enriched in these activiti...

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Bibliographic Details
Published in:Archives of microbiology 1989-01, Vol.152 (2), p.132-137
Main Authors: Radcliffe, C W, Steiner, F X, Carman, G M, Niederman, R A
Format: Article
Language:English
Subjects:
Rhodobacter sphaeroides
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Summary:Catalytic properties and membrane associations of the phosphatidyl-glycerophosphate (PGP) and phosphatidylserine (PS) synthases of Rhodobacter sphaeroides were examined to further characterize sites of phospholipid biosynthesis. In preparations of cytoplasmic membrane (CM) enriched in these activities, apparent K sub(m) values of PGP synthase were 90 mu M for sn-glycerol-3-phosphate and 60 upsilon M for CDP-diacylglycerol; the apparent K sub(m) of PS synthase for L-serine was near 165 mu M. Both enzymes required Triton X-100 with optimal PS synthase activity at a detergent/CDP-diacylglycerol (mol/mol) ratio of 7.5:1.0, while for optimal PGP synthase, a range of 10-50:1.0 was observed. Unlike the enzyme in Escherichia coli) and several other Gram-negative bacteria, the PS synthase activity had a specific requirement for magnesium and was tightly associated with membranes rather than ribosomes in crude cell extracts.
ISSN:0302-8933