Premium
Effect of a clockwise‐locked deletion in FliG on the FliG ring structure of the bacterial flagellar motor
Author(s) -
Kinoshita Miki,
Namba Keiichi,
Minamino Tohru
Publication year - 2018
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/gtc.12565
Subject(s) - biology , clockwise , flagellum , ring (chemistry) , microbiology and biotechnology , genetics , bacteria , physics , optics , amplitude , chemistry , organic chemistry
FliG is a rotor protein of the bacterial flagellar motor. FliG consists of Fli G N , Fli G M and Fli G C domains. Intermolecular Fli G M –Fli G C interactions promote FliG ring formation on the cytoplasmic face of the MS ring. A conformational change in Helix MC connecting Fli G M and Fli G C is responsible for the switching between the counterclockwise ( CCW ) and clockwise ( CW ) rotational states of the FliG ring. However, it remains unknown how it occurs. Here, we carried out in vivo disulfide cross‐linking experiments to see the effect of a CW ‐locked deletion (∆ PAA ) in FliG on the FliG ring structure in Salmonella enterica . Higher‐order oligomers were observed in the membrane fraction of the fliG (∆PAA + G166C/G194C) strain upon oxidation with iodine in a way similar to FliG(G166C/G194C), indicating that the PAA deletion does not inhibit domain‐swap polymerization of FliG. FliG(∆PAA + E174C) formed a cross‐linked homodimer whereas FliG(E174C) did not, indicating that Glu174 in Helix MC of one FliG protomer is located much closer to that of its neighboring subunit in the CW motor than in the CCW motor. We will discuss possible helical rearrangements of Helix MC that induce a structural remodeling of the FliG ring upon flagellar motor switching.