| Summary: | Tubulin, an extensively studied self-assembling protein, forms filaments in eukaryotic cells that affect cell shape, among other functions. The model archaeon <i>Haloferax volcanii</i> uses two tubulin-like proteins (FtsZ1/FtsZ2) for cell division, similar to bacteria, but has an additional six related tubulins called CetZ. One of them, CetZ1, was shown to play a role in cell shape. Typically, discoid and rod shapes are observed in planktonic growth, but under biofilm formation conditions (i.e., attached to a substratum), <i>H. volcanii</i> can grow filamentously. Here, we show that the deletion mutants of all eight tubulin-like genes significantly impacted morphology when cells were allowed to form a biofilm. <i>ΔftsZ1</i>, <i>ΔcetZ2</i>, and <i>ΔcetZ4-6</i> created longer, less round cells than the parental and a higher percentage of filaments. <i>ΔcetZ1</i> and <i>ΔcetZ3</i> were significantly rounder than the parental, and <i>ΔftsZ2</i> generated larger, flat, amorphic cells. The results show all tubulin homologs affect morphology at most timepoints, which therefore suggests these genes indeed have a function.
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