5XRW

Crystal structure of flagellar motor switch complex from H. pylori

Summary for 5XRW

• Entry DOI: 10.2210/pdb5xrw/pdb
• Descriptor: FliN, FliY (3 entities in total)
• Functional Keywords: motor switch complex, c-ring, motor protein
• Biological source: Helicobacter pylori 26695; More
• Total number of polymer chains: 4
• Total formula weight: 34854.48

Authors

Xue, C.,Lam, K.H.,Au, S.W.N. (deposition date: 2017-06-10, release date: 2018-06-13, Last modification date: 2024-03-27)

Primary citation

Lam, K.H.,Xue, C.,Sun, K.,Zhang, H.,Lam, W.W.L.,Zhu, Z.,Ng, J.T.Y.,Sause, W.E.,Lertsethtakarn, P.,Lau, K.F.,Ottemann, K.M.,Au, S.W.N.
Three SpoA-domain proteins interact in the creation of the flagellar type III secretion system inHelicobacter pylori.
J.Biol.Chem., 293:13961-13973, 2018

PubMed Abstract: Bacterial flagella are rotary nanomachines that contribute to bacterial fitness in many settings, including host colonization. The flagellar motor relies on the multiprotein flagellar motor-switch complex to govern flagellum formation and rotational direction. Different bacteria exhibit great diversity in their flagellar motors. One such variation is exemplified by the motor-switch apparatus of the gastric pathogen , which carries an extra switch protein, FliY, along with the more typical FliG, FliM, and FliN proteins. All switch proteins are needed for normal flagellation and motility in , but the molecular mechanism of their assembly is unknown. To fill this gap, we examined the interactions among these proteins. We found that the C-terminal SpoA domain of FliY (FliY) is critical to flagellation and forms heterodimeric complexes with the FliN and FliM SpoA domains, which are β-sheet domains of type III secretion system proteins. Surprisingly, unlike in other flagellar switch systems, neither FliY nor FliN self-associated. The crystal structure of the FliY-FliN complex revealed a saddle-shaped structure homologous to the FliN-FliN dimer of , consistent with a FliY-FliN heterodimer forming the functional unit. Analysis of the FliY-FliN interface indicated that oppositely charged residues specific to each protein drive heterodimer formation. Moreover, both FliY-FliM and FliY-FliN associated with the flagellar regulatory protein FliH, explaining their important roles in flagellation. We conclude that uses a FliY-FliN heterodimer instead of a homodimer and creates a switch complex with SpoA domains derived from three distinct proteins.

PubMed: 29991595
DOI: 10.1074/jbc.RA118.002263

Experimental method

X-RAY DIFFRACTION (2.5 Å)