. Many species of bacteria swim by means of flagella, helical filaments that function as propellers attached to rotary motors in the cell membrane. The flagellar motor is fueled by the membrane ion gradient and is capable of rapid rotation in either the clockwise or counterclockwise direction. By controlling reversals in motor direction, cells can direct their movement toward conditions that favor survival and growth. The structure and molecular mechanism of the flagellum is not understood in detail, but proteins with key roles in rotation and clockwise/counterclockwise switching have been identified. Rotation involves a stator (non-rotating part) formed from the membrane proteins MotA and MotB, and a rotor formed from FliG, FliM, and FliN. Recently, crystallography has been used in combination with biochemical methods to generate a model for the overall arrangement of proteins on the rotor. In the work proposed here, this structural model of the flagellar rotor will be developed further using a variety of biochemical, mutational, and structural approaches, and the new structural information will be utilized to address the molecular mechanisms of flagellar rotation, switching, and assembly. The long-term goal of this work is to understand the structure, assembly, and mechanism of the bacterial flagellar motor. Relevance. Flagellar motility is a factor in the virulence of many human pathogens, including those that cause ulcers, syphilis, urinary tract infections;burn wound infections, and some diarrhea. Furthermore, central structures in the flagellum are structurally and mechanistically related to the protein secretion apparatus (termed the type-Ill secretion system) that many pathogenic bacteria use to inject virulence factors into the cells they infect. In addition to its direct relevance for bacterial pathogenesis, the knowledge gained will have implications for the broader biological questions of cellular motility, organelle assembly, and membrane transport.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM064664-08S1
Application #
8718140
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Gindhart, Joseph G
Project Start
2001-12-01
Project End
2014-08-31
Budget Start
2010-04-01
Budget End
2014-08-31
Support Year
8
Fiscal Year
2013
Total Cost
$122,889
Indirect Cost
$29,248
Name
University of Utah
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Miller, Michael R; Miller, Kelly A; Bian, Jiang et al. (2016) Spirochaete flagella hook proteins self-catalyse a lysinoalanine covalent crosslink for motility. Nat Microbiol 1:16134
Kim, Eun A; Blair, David F (2015) Function of the Histone-Like Protein H-NS in Motility of Escherichia coli: Multiple Regulatory Roles Rather than Direct Action at the Flagellar Motor. J Bacteriol 197:3110-20
Boschert, Ryan; Adler, Frederick R; Blair, David F (2015) Loose coupling in the bacterial flagellar motor. Proc Natl Acad Sci U S A 112:4755-60
Sircar, Ria; Borbat, Peter P; Lynch, Michael J et al. (2015) Assembly states of FliM and FliG within the flagellar switch complex. J Mol Biol 427:867-86
Sircar, Ria; Greenswag, Anna R; Bilwes, Alexandrine M et al. (2013) Structure and activity of the flagellar rotor protein FliY: a member of the CheC phosphatase family. J Biol Chem 288:13493-502
Paul, Koushik; Carlquist, William C; Blair, David F (2011) Adjusting the spokes of the flagellar motor with the DNA-binding protein H-NS. J Bacteriol 193:5914-22
Paul, Koushik; Gonzalez-Bonet, Gabriela; Bilwes, Alexandrine M et al. (2011) Architecture of the flagellar rotor. EMBO J 30:2962-71
Paul, Koushik; Brunstetter, Duncan; Titen, Sienna et al. (2011) A molecular mechanism of direction switching in the flagellar motor of Escherichia coli. Proc Natl Acad Sci U S A 108:17171-6
Sarkar, Mayukh K; Paul, Koushik; Blair, David F (2010) Subunit organization and reversal-associated movements in the flagellar switch of Escherichia coli. J Biol Chem 285:675-84
Paul, Koushik; Nieto, Vincent; Carlquist, William C et al. (2010) The c-di-GMP binding protein YcgR controls flagellar motor direction and speed to affect chemotaxis by a ""backstop brake"" mechanism. Mol Cell 38:128-39

Showing the most recent 10 out of 18 publications