Probing the domain structure of FtsZ by random truncation and insertion of GFP Osawa, Masaki and Erickson, Harold P.,, 151, 4033-4043 (2005), doi = https://doi.org/10.1099/mic.0.28219-0, publicationName = Microbiology Society, issn = 1350-0872, abstract= Random transposon-mediated mutagenesis has been used to create truncations and insertions of green fluorescent protein (GFP), and Venus-yellow fluorescent protein (YFP), in Escherichia coli FtsZ. Sixteen unique insertions were obtained, and one of them, in the poorly conserved C-terminal spacer, was functional for cell division with the Venus-YFP insert. The insertion of enhanced GFP (eGFP) at this same site was not functional; Venus-YFP was found to be superior to eGFP in other respects too. Testing the constructs for dominant negative effects led to the following general conclusion. The N-terminal domain, aa 1–195, is an independently folding domain that can poison Z-ring function when expressed without a functional C-terminal domain. The effects were weak, requiring expression of the mutant at 3–5 times the level of wild-type FtsZ. The C-terminal domain, aa 195–383, was also independently folding, but had no activity in vivo. The differential activity of the N- and C-terminal domains suggests that FtsZ protofilament assembly is directional, with subunits adding primarily at the bottom of the protofilament. Directional assembly could occur by either a treadmilling or a dynamic instability mechanism., language=, type=