Revertants of Escherichia coli mutants defective in the first enzyme of membrane phospholipid synthesis, sn glycerol 3 phosphate (glycerol P) acyltransferase, were investigated. These glycerol P acyltransferase mutants, selected as glycerol P auxotrophs, contained membranous glycerol P acyltransferase activity with an apparent Km for glycerol P 10 times higher than the parental activity. The glycerol P acyltransferase activity was also more thermolabile in vitro than the parental activity. Most revertants no longer requiring glycerol P for growth regained glycerol P acyltransferase activity of normal thermolability and apparent Km for glycerol P. However, two novel revertants were isolated which retained an abnormal glycerol P acyltransferase activity. The glycerol P dehydrogenase activities of these novel revertants were about 20 fold less sensitive to feedback inhibition by glycerol P. The feedback resistant glycerol P dehydrogenase co transduced with gpsA, the structural gene for the glycerol P dehydrogenase. Further transduction experiments demonstrated that the feedback resistant glycerol P dehydrogenase phenotypically suppressed the glycerol P acyltransferase Km lesion. The existence of the class of glycerol P auxotrophs which owe their phenotype to the glycerol P acyltransferase Km lesion, therefore, depends on the feedback regulation of glycerol P synthesis in E. coli.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - 1975|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology