Enterococcus faecalis divIVA:: an essential gene involved in cell division, cell growth and chromosome segregation

Enterococcus faecalis divIVA (divIVA(Ef)) is an essential gene implicated in cell division and chromosome segregation. This gene was disrupted by insertional inactivation creating E faecalis JHSR1, which was viable only when a wild-type copy of divIVA(Ef) was expressed in trans, confirming the essentiality of the gene. The absence of DivIVA(Ef) in E faecalis JHSR1 inhibited proper cell division, which resulted in abnormal cell clusters possessing enlarged cells of altered shape instead of the characteristic diplococcal morphology of enterococci. The lower viability of the divIVA(Ef) mutant is caused by improper nucleoid segregation and impaired septation within the numerous cells generated in each cluster. Overexpression of DivIVA(Ef) in Escherichia coli KJB24 resulted in enlarged cells with disrupted cell division, suggesting that this round E coli mutant strain could be used as an indicator for functionality of DivIVA(Ef). A Bacillus subtilis divIVA mutant was not complemented by DivIVA(Ef) indicating that this protein does not recognize DivIVA-specific target sites in B. subtilis, or that it does not interact with other proteins of the cell division machinery of this micro-organism. DivIVA(Ef) also failed to complement a Streptococcus pneumoniae divIVA mutant, supporting the phylogenetic distance between Enterococcus and Streptococcus. Our results indicate that DivIVA is a species-specific multifunctional protein implicated in cell division and chromosome segregation in E faecalis.