TY - JOUR
T1 - Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold
AU - Beeby, Morgan
AU - Ribardo, Deborah A.
AU - Brennan, Caitlin A.
AU - Ruby, Edward G.
AU - Jensen, Grant J.
AU - Hendrixson, David R.
AU - Hultgren, Scott J.
N1 - Funding Information:
ACKNOWLEDGMENTS. We thank Anchi Cheng for advice on programming an additional Leginon node; Kelly Hughes for the generous gift of the Salmonella minicell strain TH16943; Tillmann Pape and Amanda Wilson for technical assistance during electron microscopy data collection; and Bonnie Chaban, Velocity Hughes, Ariane Briegel, Alain Filloux, and Richard Berry for critical reading of the manuscript. This work was supported by Biotechnology and Biological Sciences Research Council Grant BB/L023091/1 (to M.B.), Howard Hughes Medical Institute funding (G.J.J.), and National Institutes of Health Grants 5R01AI065539 and 5R21AI103643 (to D.R.H.).
PY - 2016/3/29
Y1 - 2016/3/29
N2 - Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes.
AB - Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes.
KW - Bacterial flagellar motors
KW - Campylobacter
KW - Electron cryo-tomography
KW - Macromolecular evolution
KW - Torque
UR - http://www.scopus.com/inward/record.url?scp=84962086078&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84962086078&partnerID=8YFLogxK
U2 - 10.1073/pnas.1518952113
DO - 10.1073/pnas.1518952113
M3 - Article
C2 - 26976588
AN - SCOPUS:84962086078
SN - 0027-8424
VL - 113
SP - E1917-E1926
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 13
ER -