YtfB, an OapA Domain-Containing Protein, Is a New Cell Division Protein in Escherichia coli

Abstract

While screening the Pfam database for novel peptidoglycan (PG) binding modules, we identified the OapA domain, which is annotated to be a LysM-like domain. LysM domains bind PG and mediate localization to the septal ring. In the Gram-negative bacterium , an OapA domain is present in YtfB, an inner membrane protein of unknown function but whose overproduction causes cells to filament. Together, these observations suggested that YtfB directly affects cell division, most likely through its OapA domain. Here we show that YtfB accumulates at the septal ring and that its action requires the initiating division protein FtsZ and to a lesser extent ZipA, an early recruit to the septalsome. While the loss of YtfB had no discernable impact, a mutant lacking both YtfB and DedD (a known cell division protein) grew as filamentous cells. The YtfB OapA domain by itself also localized to sites of division, and this localization was enhanced by the presence of denuded PG glycans. Finally, the OapA domain bound PG, though binding did not depend on the formation of denuded glycans. Collectively, our findings demonstrate that YtfB is a cell division protein whose function is related to cell wall hydrolases. All living cells must divide in order to thrive. In bacteria, this involves the coordinated activities of a large number of proteins that work in concert to constrict the cell. Knowing which proteins contribute to this process and how they function is fundamental. Here we identify a new member of the cell division apparatus in the Gram-negative bacterium whose function is related to the generation of a transient cell wall structure. These findings deepen our understanding of bacterial cell division.

The novel E. coli cell division protein, YtfB, plays a role in eukaryotic cell adhesion

“…Whilst the basis of different colony opaqueness has not been identified, the molecular mass of LPS has been suggested to be larger in transparent colonies (when OapA is expressed) compared to opaque colonies 11 which may suggest a functional link between LPS size and the role of OapA adhesion to host cells. We did not observe any differences in growth rate, cellular morphology or cell size between BW25113 and the isogenic mutant BW25113ΔytfB (data not shown), ruling out a role for YtfB in the maintenance of gross cellular morphology, in agreement with previous data 9 . We therefore investigated if changes in LPS mass was also observed in the presence and absence of ytfB.…”

“…YtfB was initially discovered through a genome-wide screen to identify novel cell division genes and regulators in E. coli 8 . Misexpression of ytfB results in division inhibition, resulting in filamentous cells, which has also been confirmed in this study and others 9 . YtfB has also been shown to localise to midcell in an FtsZ-dependent manner 9 .…”

“…Misexpression of ytfB results in division inhibition, resulting in filamentous cells, which has also been confirmed in this study and others 9 . YtfB has also been shown to localise to midcell in an FtsZ-dependent manner 9 . Midcell localisation is mediated by the LysM-like (OapA) domain which binds preferentially to denuded Supplementary Table 2.…”

“…We became interested in ytfB, because high expression levels caused cell division inhibition in Escherichia coli, resulting in filamentous cells 8 . Very recently, a role for YtfB in cell division was reported, with the protein initially selected for investigation due to computational annotation as containing a peptidoglycan binding domain 9 . Interestingly, bioinformatic analysis showed that YtfB shares homology with the virulence factor OapA in Haemophilus influenzae across 2 domains: a short sequence spanning the transmembrane domain proximal to the N-terminus; and a LysM-like domain at the extreme C-terminus 9 (Fig.…”

“…YtfB has also been shown to bind to denuded glycan (i.e. glycans with stem peptides removed) present in the bacterial cell wall 9 , suggesting a possible role in glycan binding for YtfB.…”