In Escherichia coli, initial assembly of the Z ring for cell division requires 
FtsZ plus the essential Z ring-associated proteins FtsA and ZipA. 
Thermosensitive mutations in ftsA, such as ftsA27, map in or near its ATP 
binding pocket and result in cell division arrest at non-permissive 
temperatures. We found that purified wild-type FtsA bound and hydrolysed ATP, 
whereas FtsA27 was defective in both activities. FtsA27 was also less able to 
localize to the Z ring in vivo. To investigate the role of ATP transactions in 
FtsA function in vivo, we isolated intragenic suppressors of ftsA27. Suppressor 
lesions in the ATP site restored the ability of FtsA27 to compete with ZipA at 
the Z ring, and enhanced ATP binding and hydrolysis in vitro. Notably, 
suppressors outside of the ATP binding site, including some mapping to the 
FtsA-FtsA subunit interface, also enhanced ATP transactions and exhibited gain 
of function phenotypes in vivo. These results suggest that allosteric effects, 
including changes in oligomeric state, may influence the ability of FtsA to bind 
and/or hydrolyse ATP.