TY - JOUR
T1 - Structural Effects of Mutations inSalmonella typhimuriumFlagellar Switch Complex
AU - Zhao, Rongbao
AU - Schuster, Stephan C.
AU - Khan, Shahid
N1 - Funding Information:
We are grateful to Professor R. M. Macnab for sharing sequence information with us prior to publication, for consultation regarding the choice of mutant strains and for their provision. We thanks Drs K. Oosawa and S.-I. Aizawa for plasmids, Dr I. H Khan and Cheng Huang for participation in the initial stages of this work and John Chludzinski (NIH, NINDS) for excellent photographic assistance. Supported by National Institutes of Health Research Grant GM36936 to S.K.
PY - 1995
Y1 - 1995
N2 - Mutations inSalmonella typhimurium fliG, fliMandfliNgive rise either to non-flagellate, non-motile or non-chemotactic mutant bacteria. The FliG, FliM and FliN proteins form part of recently characterized extended flagellar basal structures, and have been postulated to form a mutually interacting structural complex. We have examined basal body preparations from non-motile or non-chemotacticfliG, fliMandfliNmutant strains by electron microscopy and immunoblot gel analysis. Most flagellar preparations isolated from the non-motile mutants lacked FliM, but contained FliG. The basal bodies lacked the belled morphology characteristic of the wild-type structures, but had protrusions which could be labelled with anti-FliG. Non-motile mutant preparations severely depleted of FliG but containing FliM were also obtained. These preparations contained extended, belled flagellar structures that were labelled with anti-FliM. Thus, FliM is part of the shell of the extended structures responsible for the belled morphology, while FliG may be part of the inner substructure. The extended basal structures from a FliG temperature-sensitive mutant strain rapidly lost FliM, as well as FliG, upon a shift to a non-permissive temperature, implying interaction between the FliG- and FliM-containing substructures. In dramatic contrast to non-motile mutants, extended basal structures isolated from non-chemotactic mutants were indistinguishable from wild-type structures. This difference may reflect the energetics of the different protein-protein interactions operative during torque generation and the switching of rotation sense.
AB - Mutations inSalmonella typhimurium fliG, fliMandfliNgive rise either to non-flagellate, non-motile or non-chemotactic mutant bacteria. The FliG, FliM and FliN proteins form part of recently characterized extended flagellar basal structures, and have been postulated to form a mutually interacting structural complex. We have examined basal body preparations from non-motile or non-chemotacticfliG, fliMandfliNmutant strains by electron microscopy and immunoblot gel analysis. Most flagellar preparations isolated from the non-motile mutants lacked FliM, but contained FliG. The basal bodies lacked the belled morphology characteristic of the wild-type structures, but had protrusions which could be labelled with anti-FliG. Non-motile mutant preparations severely depleted of FliG but containing FliM were also obtained. These preparations contained extended, belled flagellar structures that were labelled with anti-FliM. Thus, FliM is part of the shell of the extended structures responsible for the belled morphology, while FliG may be part of the inner substructure. The extended basal structures from a FliG temperature-sensitive mutant strain rapidly lost FliM, as well as FliG, upon a shift to a non-permissive temperature, implying interaction between the FliG- and FliM-containing substructures. In dramatic contrast to non-motile mutants, extended basal structures isolated from non-chemotactic mutants were indistinguishable from wild-type structures. This difference may reflect the energetics of the different protein-protein interactions operative during torque generation and the switching of rotation sense.
KW - Bacterial chemotaxis
KW - Flagellar basal body
KW - Immunoelectron microscopy
KW - Molecular motor
KW - Protein-protein interactions
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U2 - 10.1006/jmbi.1995.0443
DO - 10.1006/jmbi.1995.0443
M3 - Article
C2 - 7650739
AN - SCOPUS:0029091434
SN - 0022-2836
VL - 251
SP - 400
EP - 412
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 3
ER -