Effects of lipoprotein biogenesis mutations on flagellar assembly in Salmonella.
Flagellar assembly requires the expression of a large number of flagellum-specific genes. However, mutations in a number of other genes in Salmonella and Escherichia coli have been shown to have pleiotropic effects that affect flagellar assembly. FlgH (the L-ring subunit of the flagellar basal body) is a lipoprotein whose modification is important for L-ring assembly. We therefore tested whether the lack of motility of Salmonella mutants defective in lipoprotein biogenesis is a result of inability to modify FlgH. Our results show that temperature-sensitive apolipoprotein N-acyltransferase [lnt(Ts)] mutants are nonflagellate at 42 degrees C. However, the flagellar assembly defect occurs at a much earlier step in the pathway than L-ring assembly. These mutants failed to assemble even an MS ring, presumably because of the observed decrease in transcription of fliF. In contrast, temperature-sensitive diacylglycerol transferase [lgt(Ts)] mutants were motile at 42 degrees C, provided the strains carried an lpp (Braun lipoprotein) mutation to permit growth. We have isolated second-site mutants from an lgt(Ts) lpp(+) strain that grow but are nonflagellate at 42 degrees C. Thus, lipoprotein biogenesis is a factor that is important for flagellar assembly.
Dailey
Frank E
FE
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
Macnab
Robert M
RM
D000217:Acyltransferases / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics; D005407:Flagella / Q000502:physiology*; D008074:Lipoproteins / Q000096:biosynthesis*; D008565:Membrane Proteins; D009068:Movement; D009154:Mutation; D012486:Salmonella typhimurium / Q000235:genetics*
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C100967:FlgH protein, Salmonella typhimurium; C075661:Flif protein, Bacteria; D008074:Lipoproteins; D008565:Membrane Proteins; D000217:Acyltransferases; C068902:apolipoprotein N-acyltransferase