A possible role for L24 of Bacillus subtilis in nucleoid organization and segregation

The condensation of DNA in bacterial nucleoids during cell cycle is a compl ex and dynamic process. Proteins displaying the physico-chemical properties of histones are known to contribute to this process. During a search for B . subtilis nucleoid associated proteins, HBsu and L24 were identified as th e most abundant proteins in nucleoid containing fractions. Purified L24 bin ds and condenses DNA in vitro. In this paper we describe immunofluorescence studies that demonstrated that L24 is located at the poles of the nucleoid s in exponentially growing cells. In contrast, the protein is dispersed in the cytoplasm during stationary phase. Moreover, overexpression of the rplX gene encoding L24 disrupts nucleoid segregation and positioning. (C) 2001 Societe francaise de biochimie et biologie moleculaire / Editions scientifi ques et medicales Elsevier SAS.