TY - JOUR
T1 - In situ imaging of the bacterial flagellar motor disassembly and assembly processes
AU - Kaplan, Mohammed
AU - Subramanian, Poorna
AU - Ghosal, Debnath
AU - Oikonomou, Catherine M.
AU - Pirbadian, Sahand
AU - Starwalt-Lee, Ruth
AU - Mageswaran, Shrawan Kumar
AU - Ortega, Davi R.
AU - Gralnick, Jeffrey A.
AU - El-Naggar, Mohamed Y.
AU - Jensen, Grant J.
N1 - Publisher Copyright:
© 2019 The Authors
PY - 2019/7/15
Y1 - 2019/7/15
N2 - The self-assembly of cellular macromolecular machines such as the bacterial flagellar motor requires the spatio-temporal synchronization of gene expression with proper protein localization and association of dozens of protein components. In Salmonella and Escherichia coli, a sequential, outward assembly mechanism has been proposed for the flagellar motor starting from the inner membrane, with the addition of each new component stabilizing the previous one. However, very little is known about flagellar disassembly. Here, using electron cryo-tomography and sub-tomogram averaging of intact Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis cells, we study flagellar motor disassembly and assembly in situ. We first show that motor disassembly results in stable outer membrane-embedded sub-complexes. These sub-complexes consist of the periplasmic embellished P- and L-rings, and bend the membrane inward while it remains apparently sealed. Additionally, we also observe various intermediates of the assembly process including an inner-membrane sub-complex consisting of the C-ring, MS-ring, and export apparatus. Finally, we show that the L-ring is responsible for reshaping the outer membrane, a crucial step in the flagellar assembly process.
AB - The self-assembly of cellular macromolecular machines such as the bacterial flagellar motor requires the spatio-temporal synchronization of gene expression with proper protein localization and association of dozens of protein components. In Salmonella and Escherichia coli, a sequential, outward assembly mechanism has been proposed for the flagellar motor starting from the inner membrane, with the addition of each new component stabilizing the previous one. However, very little is known about flagellar disassembly. Here, using electron cryo-tomography and sub-tomogram averaging of intact Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis cells, we study flagellar motor disassembly and assembly in situ. We first show that motor disassembly results in stable outer membrane-embedded sub-complexes. These sub-complexes consist of the periplasmic embellished P- and L-rings, and bend the membrane inward while it remains apparently sealed. Additionally, we also observe various intermediates of the assembly process including an inner-membrane sub-complex consisting of the C-ring, MS-ring, and export apparatus. Finally, we show that the L-ring is responsible for reshaping the outer membrane, a crucial step in the flagellar assembly process.
KW - assembly
KW - bacterial flagellar motor
KW - disassembly
KW - electron cryo-tomography
KW - in situ imaging
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U2 - 10.15252/embj.2018100957
DO - 10.15252/embj.2018100957
M3 - Article
C2 - 31304634
AN - SCOPUS:85066107011
SN - 0261-4189
VL - 38
JO - EMBO Journal
JF - EMBO Journal
IS - 14
M1 - e100957
ER -