Characterization of C-ring component assembly in flagellar motors from amino acid coevolution

Author(s)

dos Santos, Ricardo Nascimento ^{[1, 2]} ; Khan, Shahid ^[3] ; Morcos, Faruck ^{[4, 5, 6]}

Affiliation

^[1] Univ Estadual Campinas, Inst Chem, Campinas, SP - Brazil

^[2] Univ Estadual Campinas, Ctr Computat Engn & Sci, Campinas, SP - Brazil

^[3] Lawrence Berkeley Natl Lab, Mol Biol Consortium, Berkeley, CA - USA

^[4] Univ Texas Dallas, Dept Biol Sci, Richardson, TX 75083 - USA

^[5] Univ Texas Dallas, Dept Bioengn, Richardson, TX 75083 - USA

^[6] Univ Texas Dallas, Ctr Syst Biol, Richardson, TX 75083 - USA

• Document type: Journal article
• Source: ROYAL SOCIETY OPEN SCIENCE; v. 5, n. 5 MAY 2018.
• Web of Science Citations: 2

Abstract

Bacterial flagellar motility, an important virulence factor, is energized by a rotary motor localized within the flagellar basal body. The rotor module consists of a large framework (the C-ring), composed of the FliG, FliM and FliN proteins. FliN and FliM contacts the FliG torque ring to control the direction of flagellar rotation. We report that structure-based models constrained only by residue coevolution can recover the binding interface of atomic X-ray dimer complexes with remarkable accuracy (approx. 1 angstrom RMSD). We propose a model for FliM-FliN heterodimerization, which agrees accurately with homologous interfaces as well as in situ cross-linking experiments, and hence supports a proposed architecture for the lower portion of the C-ring. Furthermore, this approach allowed the identification of two discrete and interchangeable homodimerization interfaces between FliM middle domains that agree with experimental measurements and might be associated with C-ring directional switching dynamics triggered upon binding of CheY signal protein. Our findings provide structural details of complex formation at the C-ring that have been difficult to obtain with previous methodologies and clarify the architectural principle that underpins the ultra-sensitive allostery exhibited by this ring assembly that controls the clockwise or counterclockwise rotation of flagella. (AU)

• FAPESP's process: 15/13667-9 - Studies of multimeric protein systems through cross-linking, mass spectrometry and molecular modeling
• Grantee: Ricardo Nascimento dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral