Division plane placement in pleomorphic archaea is dynamically coupled to cell shape

Abstract

Summary One mechanism for achieving accurate placement of the cell division machinery is via Turing patterns, where nonlinear molecular interactions spontaneously produce spatiotemporal concentration gradients. The resulting patterns are dictated by cell shape. For example, the Min system of Escherichia coli shows spatiotemporal oscillation between cell poles, leaving a mid‐cell zone for division. The universality of pattern‐forming mechanisms in divisome placement is currently unclear. We examined the location of the division plane in two pleomorphic archaea, Haloferax volcanii and Haloarcula japonica, and showed that it correlates with the predictions of Turing patterning. Time‐lapse analysis of H. volcanii shows that divisome locations after successive rounds of division are dynamically determined by daughter cell shape. For H. volcanii, we show that the location of DNA does not influence division plane location, ruling out nucleoid occlusion. Triangular cells provide a stringent test for Turing patterning, where there is a bifurcation in division plane orientation. For the two archaea examined, most triangular cells divide as predicted by a Turing mechanism; however, in some cases multiple division planes are observed resulting in cells dividing into three viable progeny. Our results suggest that the division site placement is consistent with a Turing patterning system in these archaea.

Live cell imaging of the hyperthermophilic archaeonSulfolobus acidocaldariusidentifies complementary roles for two ESCRTIII homologues in ensuring a robust and symmetric cell division

“…Live imaging is essential for the understanding of complex dynamic cellular events, such as changes in cell shape, cell division and DNA segregation. Despite such methods being well-established in bacteria and eukaryotes, live imaging has only recently been applied to the study of cell biological processes in archaea [1], where imaging of halophilic archaea has led to surprising new findings [2][3][4][5]. Live imaging of archaea remains challenging, especially when compared to bacteria, because archaea tend to be mechanically soft and several representatives are extremophiles, necessitating the development of novel techniques [1,2].…”

Lipid Anchoring of Archaeosortase Substrates and Mid-Cell Growth in Haloarchaea

“…However, haloarchaea might have conserved at least two distinct elongation modes in addition to cell division, generating disk-like and rod-like populations (32). This scenario would also corroborate the morphological malleability of haloarchaea, being capable of assuming unusual shapes like triangles and squares (33,34).…”

“…Then, 10 µl of the concentrated cells was transferred to under a 0.5% agarose pad with CA medium and observed using a Nikon Eclipse TiE inverted TIRF microscope. ArtA-msfGFP time lapses were acquired by culturing H. volcanii cells inside Millipore ONIX CellAsic microfluidic plates as previously described (33). Images were taken under 5-minute intervals for 12 hours in both phase contrast and with 488 nm laser channels.…”

An oscillating MinD protein determines the cellular positioning of the motility machinery in archaea

“…Movies were acquired for half an hour at one frame per 10 seconds using 100 ms exposures with 30 mW 488 nm laser illumination. Calculation of parameters of oscillation: Cell shape outlines and their respective lowest harmonic modes were detected using software available publicly on Github at: https://github.com/lilbutsa/Archaea_Division_Analysi s as described in 45 . The magnitude of oscillations were calculated by taking the inner product of the lowest harmonic mode of each cell shape with their respective fluorescent signal for each frame 73 .…”

“…To assess if ParA/MinD homologs in archaea play a role in cellular positioning, we selected the model archaeon Haloferax volcanii, which has genetic tools and fluorescent fusion proteins available to address questions relating to intracellular organization. Recent work in H. volcanii has indicated that positioning of the motility structure, chemosensory arrays and cell division machinery is regulated by unknown mechanisms [43][44][45] . H. volcanii cells display different shapes dependent on the growth stage of the culture 43,44,46 .…”