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. Author manuscript; available in PMC: 2010 Jul 21.
Published in final edited form as: Biochemistry. 2009 Jul 21;48(28):6664–6673. doi: 10.1021/bi8022653

Figure 8.

Figure 8

Mechanisms that should contribute to FtsZ filament dynamics at steady state. Two possibilities are presented for the pathway of GTP hydrolysis. (A1) Fragmentation following GTP hydrolysis. Hydrolysis is postulated to occur randomly within the protofilament, leaving ~50% of the subunits with GDP. Fragmentation is favored at GDP subunits, after which the terminal subunit can exchange its GDP for GTP in solution. (A2) Dissociation of GDP subunits only at the end. Because of cooperativity, GDP may not cause fragmentation but can dissociate only when the subunit arrives at the end of the protofilament (19,20). Internal GDP subunits would arrive at the end following dissociation of GTP subunits (panel B), and when at the end they would rapidly dissociate. (B) FtsZ–GTP subunits reversibly dissociate and reassociate from the ends, without GTP hydrolysis. The free subunits can exchange nucleotide with the solution, although exchanging GTP for GTP has no effect. (C) Annealing. Any protofilament with a GTP on its plus end may be able to anneal with the minus end of any other protofilament.