Alteration in the contents of unsaturated fatty acids in dnaA mutants of Escherichia coli.
DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli, has a high affinity for acidic phospholipids containing unsaturated fatty acids. We have examined here the fatty acid composition of phospholipids in dnaA mutants. A temperature-sensitive dnaA46 mutant showed a lower level of unsaturation of fatty acids (ratio of unsaturated to saturated fatty acids) at 42 degrees C (non-permissive temperature) and at 37 degrees C (semi-permissive temperature), but not at 28 degrees C (permissive temperature), compared with the wild-type strain. Plasmid complementation analysis revealed that the dnaA46 mutation is responsible for the phenotype. Other temperature-sensitive dnaA mutants showed similar results. On the other hand, a cold-sensitive dnaAcos mutant, in which over-initiation of DNA replication occurs at low temperature (28 degrees C), showed a higher level of unsaturation of fatty acids at 28 degrees C. Based on these observations, we discuss the role of phospholipids in the regulation of the activity of DnaA protein.
Suzuki
E
E
Preclinical Development Laboratories, Research and Development Division, Nippon Hoechst Marion Roussel, Ltd, Minamidai, Kawagoe, Japan.
Kondo
T
T
Makise
M
M
Mima
S
S
Sakamoto
K
K
Tsuchiya
T
T
Mizushima
T
T
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000032:analysis* / Q000378:metabolism; D005816:Genetic Complementation Test; D009154:Mutation; D010743:Phospholipids / Q000032:analysis*; D010957:Plasmids / Q000235:genetics; D018741:Replication Origin / Q000235:genetics; D013696:Temperature
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids