Suzuki E, Kondo T, Makise M, Mima S, Sakamoto K, Tsuchiya T, Mizushima T
Preclinical Development Laboratories, Research and Development Division, Nippon Hoechst Marion Roussel, Ltd, Minamidai, Kawagoe, Japan.
Mol Microbiol. 1998 Apr;28(1):95-102. doi: 10.1046/j.1365-2958.1998.00777.x.
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.
