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Structure. 2016 Nov 1;24(11):1886-1897. doi: 10.1016/j.str.2016.08.010. Epub 2016 Sep 22.

Crystal Structure of a Type IV Pilus Assembly ATPase: Insights into the Molecular Mechanism of PilB from Thermus thermophilus.

Author information

1
Department of Biological Sciences, Virginia Polytechnic Institute and State University, 125 Life Sciences 1 (MC 0910), 970 Washington Street Southwest, Blacksburg, VA 24061, USA.
2
Biology Department, Brookhaven National Laboratory, Upton, NY 11973-5000, USA.
3
Department of Biological Sciences, Virginia Polytechnic Institute and State University, 125 Life Sciences 1 (MC 0910), 970 Washington Street Southwest, Blacksburg, VA 24061, USA. Electronic address: fschubot@vt.edu.

Abstract

Type IV pili (T4P) mediate bacterial motility and virulence. The PilB/GspE family ATPases power the assembly of T4P and type 2 secretion systems. We determined the structure of the ATPase region of PilB (PilBATP) in complex with ATPγS to provide a model of a T4P assembly ATPase and a view of a PilB/GspE family hexamer at better than 3-Å resolution. Spatial positioning and conformations of the protomers suggest a mechanism of force generation. All six PilBATP protomers contain bound ATPγS. Two protomers form a closed conformation poised for ATP hydrolysis. The other four molecules assume an open conformation but separate into two pairs with distinct active-site accessibilities. We propose that one pair represents the post-hydrolysis phase while the other pair appears poised for ADP/ATP exchange. Collectively, the data suggest that T4P assembly is powered by coordinating concurrent substrate binding with ATP hydrolysis across the PilB hexamer.

PMID:
27667690
DOI:
10.1016/j.str.2016.08.010
[Indexed for MEDLINE]
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