Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis?

Abstract

The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.

Evolution of multicellular longitudinally dividing oral cavity symbionts (Neisseriaceae)

“…Permanent cell shape transitions may have resulted from modi cations (e.g., gene deletions, insertions and nucleotide polymorphisms) of genetic loci involved in morphogenesis (e.g., mreB, amiC2) and, additionally, in those involved in their transcriptional regulation (e.g., mraZ). Two evolutionary scenarios were proposed (den Blaauwen, 2018;Pende et al, 2018;Thanbichler, 2018): (1) an ancestral rod was compressed by its poles so that it got shorter and fatter, or (2) an ancestral rod rotated its septation axis by 90 degrees. Our results suggest that, in the course of evolution, the cell width of an ancestral rod increased (and its length decreased), perhaps following a misbalance between elongation and division.…”

“…Curiously, single amino acid mutations in the FtsZ-binding protein Ssg resulted in longitudinally dividing Streptomyces (Xiao et al, 2021). Collectively, these ndings led to the hypothesis that longitudinal division might have evolved from differential regulation of subtly different MreB and/or FtsZ variants (den Blaauwen, 2018;Thanbichler, 2018).…”

Cell Shape and Antibiotic Resistance Are Maintained by the Activity of Multiple FtsW and RodA Enzymes in Listeria monocytogenes

“…Bacterial cell elongation and cell division need to be tightly regulated to maintain cell shape. This is accomplished by two multiprotein complexes, the elongasome and divisome, which are coordinated by the actin homolog MreB and the tubulin homolog FtsZ, respectively (30–32, 59, 60). The SEDS protein FtsW is part of the divisome and essential for growth as shown for many bacteria, including E.…”

A Bidimensional Segregation Mode Maintains Symbiont Chromosome Orientation toward Its Host

“…Subsequently, as the bacterium-animal association became more and more stable, the Ca. T. oneisti predecessor would lose its flagellum [88], and the evolutionary pressure to maximize the number of cells per unit of nematode surface (or other yet unknown physiological constraints) would ''squeeze'' it laterally [89,90]. In such an evolutionary scenario, the ancestrally polar ori and ter would have ended up occupying the cell center of the symbiont, or in other words, the typical longitudinal chromosome arrangement characteristic of flagellated, polar rods [12,83,91] would become transverse.…”