Effects of cadA gene on cell division phenotype.

Studying cell division regulatory mechanisms in Escherichia coli an important role of cad operon was discovered. The cadA gene is part of the cad operon. The promotor of cad operon (pBA) regulates two genes, cadB (the first gene in the cad operon) and cadA (the second one). The cadB encodes the lysine-cadaverine antiporter. The cadA gene encodes enzyme lysine decarboxylase that turns lysine into cadaverine and carbon dioxide. The expression of cadA is activated by several different environmental parameters, such as low pH, low oxygen, and excess lysine. Regulation of any of these parameters depends on the presence of cadC gene, encoding the regulator of the operon. It is located upstream of cad operon. The aim of this study is to investigate if the effect upon the cell division rate was caused by the induction of cadA. Specific aims were to obtain structural gene of cadA and construct a plasmid (pAM1) that contains cadA under the control of the arabinose inducibile promoter pARA, and complement the cell division phenotype of a cadA mutant by providing cadA on the inducibile plasmid. Activation of the pAM1 with 0.05% arabinose reduced the cell division rate that confirms the inhibitory effect of the pAM1.