ASPC Mediated Aspartate Metabolismcoordinates The Cell Cycle Of Escherichia Coli

Different stages of E.coli Cell cycle are coordinated with each other, however, the mechanism behind it especially the link between amino acid metabolism and cell cycle is not clear yet. AspC is an aspartate aminotransferase, which mainly catalyzes synthesis of aspartate. Deletion of aspC resulted in DNA replication delay, cell growth rate slow down and cell length shorten, while introduction of aspC compensated these defects. Overproduction of aspC in wild type cells leads to DNA replication a little ahead of time and cell size larger. DnaA amount but not concentration decrease distinctly in AaspC mutant. We demonstrated that the deficiency of aspartate synthesis led to replication initiation delayed in△aspC mutant. However, small molecule (p) ppGpp which reponses to amino acid starvation seems not be involved in the control of this program. Deletion of enzymes which catalyzes other amino acids synthesis do not yield obviously defects on cell cycle compared with wild-type cells. Extra aspartate in medium make DNA replication initiates earilier and cell size slightly larger. It is estimated that AspC mediated aspartate metabolism maybe regulates E.coli cell cycle specially. Homology analysis reveals that the amnio acid sequence of aminotransferase has a high identity among microorganism, plants and animals, suggested that AspC may be significant to life.