YgbQ, a cell division protein in Escherichia coli and Vibrio cholerae , localizes in codependent fashion with FtsL to the division site

Abstract

YgbQ is a cell division protein in Escherichia coli and Vibrio cholerae. In E. coli the ygbQ gene was discovered as a result of a computer search of the E. coli genome designed to find potential interacting partners for cell division protein FtsL. In V. cholerae, ygbQ was identified as an essential gene by using a transposon that fuses genes to an arabinose promoter. The role of YgbQ in cell division is supported by the following. Cells depleted of YgbQ in both organisms form long filaments, but DNA segregation is not affected. YgbQ localizes to the constriction site in wild-type E. coli cells. Localization of E. coli YgbQ to the constriction site depends on cell division proteins FtsQ and FtsL but not FtsW and FtsI, placing YgbQ in the sequential dependency order of proteins localizing to the division site. Localization of green fluorescent protein-FtsL also depends on YgbQ, indicating that FtsL and YgbQ colocalize to the division site in E. coli. Our results show colocalization of proteins to the bacterial midcell in E. coli and raise the possibility that these proteins interact in a coiled-coil structure.C ell division in bacteria takes place at the midcell and occurs after the DNA has been duplicated and segregated into two daughter nucleoids. In Escherichia coli, this process requires a set of at least nine proteins that localize to the constriction site or septum. These proteins coordinate invagination of the cell membrane, inward growth of the peptidoglycan layer, and, finally, separation of daughter cells. The nine proteins, FtsZ, FtsA, ZipA, FtsK, FtsQ, FtsL, FtsW, FtsI, and FtsN, have been identified largely through genetic approaches. Because no systematic genetic approach for identifying such proteins has been performed or devised, there could be a number of thus-farundiscovered proteins that play a role in cell division. Information is available regarding function for only a few of these proteins (reviewed in refs. 1 and 2).Studies from a number of laboratories have led to a sequential dependency model for the assembly of this group of proteins at the cell septum (3). FtsZ arrives first at the cell septum, providing a scaffold for the recruitment of subsequent proteins. FtsA and ZipA localize to the septum independently of each other, but each depends on the presence of FtsZ for localization. The remaining proteins assemble at midcell in a strictly sequential dependency order as follows: FtsK-FtsQ-FtsL-FtsW-FtsIFtsN. The mechanisms for this order of recruitment are not understood.The work reported here arose from projects with different goals in the Beckwith and Mekalanos laboratories. The Beckwith laboratory has studied cell division in E. coli by focusing attention on three proteins, FtsQ, FtsL, and FtsI. These proteins have similar membrane topologies, i.e., a short amino-terminal domain facing the cytoplasm, a single transmembrane segment, and a carboxyl-terminal domain located in the periplasm. FtsL has a leucine zipper-like motif in its periplasmic domain, indicating that it may form coiled-co...

Cytokinesis in Bacteria

“…These experiments have revealed surprising differences between the two organisms. In E. coli, the dependence pathway for assembly is, with one recent exception (22), completely linear (Table 1; (Table 2; Fig. 2D) (54).…”

“…One important factor controlling FtsL turnover in B. subtilis is DivIB protein (34), as described below. Recently, a new essential cell division gene, ygbQ, was identified in Vibrio cholerae and E. coli (22). Depletion of the protein gave a filamentous phenotype typical of other cell division mutants.…”

A transcriptional response to replication status mediated by the conserved bacterial replication protein DnaA

“…Many bacteria have FtsL homologues that are likely unstable and DnaA regulated (Fig. 4 and Table 3) (49). Therefore, the inhibition of cell division by DnaA-mediated inhibition of ftsL may be conserved.…”

Central Domain of DivIB Caps the C-terminal Regions of the FtsL/DivIC Coiled-coil Rod

“…When the temporality of the recruitment was examined, FtsQ(DivIB) was found to belong to the late recruits, together with the proteins involved in cell wall assembly (5). In E. coli, the presence of FtsL and FtsB at the division site is mutually dependent, and their localization depends on that of FtsQ (6,7). In B. subtilis, the presence of FtsL and DivIC at mid-cell depends on that of DivIB, at the temperature at which DivIB is essential, and reciprocally (8,9).…”

“…The good agreement between the radii of gyration and the maximum extension of the particle (L ϭ D max ) was checked using the relationship in Equation 6.…”