Abstract
PilT is a hexameric ATPase required for bacterial type IV pilus retraction and surface motility. Crystal structures of ADP- and ATP-bound Aquifex aeolicus PilT at 2.8 and 3.2 Å resolution show N-terminal PAS-like and C-terminal RecA-like ATPase domains followed by a set of short C-terminal helices. The hexamer is formed by extensive polar subunit interactions between the ATPase core of one monomer and the N-terminal domain of the next. An additional structure captures a nonsymmetric PilT hexamer in which approach of invariant arginines from two subunits to the bound nucleotide forms an enzymatically competent active site. A panel of pilT mutations highlights the importance of the arginines, the PAS-like domain, the polar subunit interface, and the C-terminal helices for retraction. We present a model for ATP binding leading to dramatic PilT domain motions, engagement of the arginine wire, and subunit communication in this hexameric motor. Our conclusions apply to the entire type II/IV secretion ATPase family.
Original language | English (US) |
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Pages (from-to) | 363-376 |
Number of pages | 14 |
Journal | Structure |
Volume | 15 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2007 |
Bibliographical note
Funding Information:We are grateful to Dr. James Keck for data collection on C2 crystals. We acknowledge the excellent technical assistance of APS staff at BioCARS (14 ID-B) and LS-CAT (32 ID-B) beamlines. This project was funded by the NIH (GM59721) and the W.M. Keck Foundation.
Keywords
- CELLBIO
- MICROBIO