Growth in width and FtsZ ring longitudinal positioning in a gammaproteobacterial symbiont.

Rod-shaped bacteria usually grow in length and place their FtsZ ring and division site at midcell, perpendicular to their long axis [1,2]. Here, we provide morphometric and immunocytochemical evidence that a nematode-associated gammaproteobacterium [3,4] grows in width, sets a constricting FtsZ ring parallel to its long axis, and divides longitudinally by default. Remarkably, the newly described FtsZ ring appears to be not only 90° shifted with respect to model rods, but also elliptical and discontinuous. This reveals an unexpected versatility of the gammaproteobacterial cytokinetic machinery.