CDI family systems are found only in eubacteria and are comprised of two proteins: the FtsE ABC and the FtsX IM. The ABC is very similar to those of the PAO family. The ftsE(Ts) mutation of E. coli causes defects in cell division and cell growth. An FtsE null mutant showed filamentous growth and appeared viable on high salt medium only, indicating a role for FtsE in cell division and/or salt transport ( Pubmed : 10048040 ) . Recently, it was shown that the membrane insertion of the KdpA potassium transporter is affected in ftsE mutants ( Pubmed : 9658012 ) . It is therefore possible that CDI systems play a role in the proper membrane targeting or insertion of some proteins essential for septum formation.