title: Aquifex aeolicus PilT, homologue of a surface motility protein, is a thermostable oligomeric NTPase.
abstract: Bacterial surface motility works by retraction of surface-attached type IV pili. This retraction requires the PilT protein, a member of a large family of putative NTPases from type II and IV secretion systems. In this study, the PilT homologue from the thermophilic eubacterium Aquifex aeolicus was cloned, overexpressed, and purified. A. aeolicus PilT was shown to be a thermostable ATPase with a specific activity of 15.7 nmol of ATP hydrolyzed/min/mg of protein. This activity was abolished when a conserved lysine in the nucleotide-binding motif was altered. The substrate specificity was low; UTP, CTP, ATP, GTP, dATP, and dGTP served as substrates, UTP having the highest activity of these in vitro. Based on sedimentation equilibrium and size exclusion chromatography, PilT was identified as a approximately equal 5- to 6-subunit oligomer. Potential implications of the NTPase activity of PilT in pilus retraction are discussed.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Herdendorf
authors.forename: Darrell R
authors.initials: DR
authors.lastname: McCaslin
authors.forename: Katrina T
authors.initials: KT
authors.lastname: Forest
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003001:Cloning, Molecular; D019281:Dimerization; D004795:Enzyme Stability; D006358:Hot Temperature; D020409:Molecular Motor Proteins; D008969:Molecular Sequence Data; D043583:Nucleoside-Triphosphatase; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; D017766:Acid Anhydride Hydrolases; D000251:Adenosine Triphosphatases; D043583:Nucleoside-Triphosphatase