期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：13
页码：5956-5960
DOI：10.1073/pnas.89.13.5956
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have used electron microscopy to examine freshly isolated Salmonella typhimurium and Escherichia coli basal flagellar fragments, purified without resort to extremes of pH or ionic strength. Such fragments contain the large bell-like basal structures visualized recently in freeze-substituted or fixed preparations. We have found mot (non-motile) mutants produced by lesions in fli genes (G, M, N) in which the bell structures do not coisolate with the flagellar basal body. The coisolation of the bell with the flagellar basal body was unaffected in strains lacking the genes for the motility-associated Mot proteins or for the Che family of proteins, which are necessary for chemotaxis. Proper assembly and interaction of the cytoplasmically located bell with the membrane-associated flagellar basal structures appears to be necessary for motor function. The FliG, FliM, and FliN proteins are thought to form a structural complex responsible for energization and switching of the flagellar motor. Our findings are consistent with the existence of such a complex and imply that it forms part of the flagellar bell.
