Characterization and mapping of temperature-sensitive division initiation mutations of Bacillus subtilis

Abstract

Two temperature-sensitive filamenting mutants of Bacillus subtilis (tsl and tsl2) have been shown to be defective in the initiation of septation. Recombination index mapping showed that these mutations mapped in two different but closely linked genes. A third proposed initiation mutation, tms-12, probably maps in the same gene as tsl2. Another proposed initiation mutation was not linked with these genes by transfornation, indicating that there was a minimum of three genes involved in the initiation of division. PBS1 transduction mapping located these three genes close to the pyr cluster.

The membrane‐bound cell division protein DivIB is localized to the division site in Bacillus subtilis

“…It is likely that DivIB becomes localized before septum invagination, as it is known to be required for division initiation (Callister and Wake, 1981;see Harry and Wake, 1989). The observation that most of the cells that had just completed septation but had not fully separated showed DivIB immunostaining suggests that DivIB remains localized at the septum site throughout the division process and raises the possibility that DivIB is additionally involved in septum elongation.…”

“…It is probable that the other membrane-bound vegetative division proteins of B. subtilis, DivIC (Levin and Losick, 1994), PBP2B (Yanouri et al, 1993) and YllD (or FtsL;Daniel et al, 1996), have a similar topography. Although its biochemical role in cell division is not known, DivIB has been shown to be required for the very early stages of septum formation (Callister and Wake, 1981; see Harry and Wake, 1989). It has also been established that the external C-terminal portion of DivIB is important for its function, and it has been proposed that this portion of DivIB interacts with another protein (or proteins) on the exterior surface of the membrane to initiate septum formation (Harry et al, 1993).…”

“…It has been suggested that FtsZ is a cytoskeletal protein and plays a key role in septum localization (Bi and Lutkenhaus, 1991;Lutkenhaus, 1993). Like DivIB, FtsZ is involved in the early stages of septum formation in B. subtilis (Callister and Wake, 1981;see Harry and Wake, 1989) and E. coli (see Lutkenhaus, 1990). Recently, FtsA has been shown to localize to the division site in E. coli ; such localization in this organism is completely dependent on FtsZ ring formation (Addinall and Lutkenhaus, 1996b).…”

DivIB, FtsZ and cell division in Bacillus subtilis

“…Several genes involved in cell division and cell-wall synthesis in Bacillus subtilis are clustered at the Ϸ135Њ position on the chromosome (Errington, 1993). Two of the genes, divIB (also called dds) and ftsZ, have roles in the very early stages of septum formation (Callister and Wake, 1981;Beall et al, 1988;Beall and Lutkenhaus, 1989;Harry and Wake, 1989). Although DivIB in B. subtilis is not essential for viability at low temperatures (< 30ЊC), it clearly has an important role in the survival of this organism (Beall and Lutkenhaus, 1989).…”

The Bacillus subtilis division protein DivIC is a highly abundant membrane‐bound protein that localizes to the division site

“…Vegetative cell division in the rod-shaped Bacillus subtilis involves the formation of a septum at the mid-point of elongating cells. Several genes known to be involved in this process have already been identified, including ftsZ, ftsA , pbpB, divIB and divIC (Callister and Wake, 1981;Beall et al, 1988;Beall and Lutkenhaus, 1989;Harry and Wake, 1989;Yanouri et al, 1993;Levin and Losick, 1994). All of these, except divIC, reside at approximately 133-135Њ on the chromosome; divIC is located outside this cluster at approximately 6Њ.…”