The Bacterial Tubulin Homolog FtsZ Forms 2D-sheets that Sustain Electrical Oscillations

CANTERO MR; BONACINA J; CANTIELLO HF ; CARABAJAL MPA

Congreso; Biophysical Society Annual Meeting; 2020

FtsZ, a major cytoskeletal protein present in all bacteria and archaea forms a cytokinetic ring, the Z ring, at the site of septation, which directs cytokinesis. Multiple sequence alignment and secondary structure predictions indicate that bacterial FtsZ is a homolog of the eukaryotic tubulins which, as their mammalian counterpart, binds guanine nucleotides, has GTPase activity, and is able to assemble into protofilamental structures in a GTP-dependent manner. Previous studies from our laboratory demonstrated that microtubule (MTs) structures isolated from murine, bovine and apian brains spontaneously generate electrical oscillations and bursts of electrical activity similar to action potentials. Although the electrical behavior of brain MTs may have important implication in eukaryotic cell function, no information is available as to whether FtsZ may share similar properties. Therefore, the aim of the present study was to explore whether FtsZ protofilamental sheets may sustain electrical activity. FtsZ protein from E. coli ATCC 25922 was purified by ammonium sulfate precipitation, and assembled into protofilamental sheets by incubation with a polymerization buffer. 2D FtsZ sheets were voltage-clamped, and gigaseals obtained in most experiments (n = 7). Subsequently, electrical recordings from output currents were obtained, showing a complex oscillatory behavior with several peak frequencies between 7 and 110 Hz in the power spectra. As a result, it was observed that FtsZ 2D sheets had a much wider range of frequencies compared to MTs sheets from eukaryotic origin. The findings demonstrate that FtsZ protofilamental sheets are capable of generating electrical signals and behave as electrical oscillators that may be relevant to the cell division process and/or yet unknown signaling mechanisms.