Affiliation:
1. Department of Biology, University of Utah, Salt Lake City, Utah 84112
2. CREST Soft Nano-machine Project, JST, Innovation Plaza Hiroshima, 3-10-23 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
Abstract
ABSTRACT
Upon completion of the flagellar hook-basal body (HBB) structure, the flagellar type III secretion system switches from secreting rod/hook-type to filament-type substrates. The secretion specificity switch has been reported to occur prematurely (prior to HBB completion) in
flk
-null mutants (P. Aldridge, J. E. Karlinsey, E. Becker, F. F. Chevance, and K. T. Hughes, Mol. Microbiol. 60:630-643, 2006) and in distal rod gene gain-of-function mutants (
flgG
* mutants) that produce filamentous rod structures (F. F. Chevance, N. Takahashi, J. E. Karlinsey, J. Gnerer, T. Hirano, R. Samudrala, S. Aizawa, and K. T. Hughes, Genes Dev.
21:
2326-2335, 2007). A fusion of β-lactamase (Bla) to the C terminus of the filament-type secretion substrate FlgM was used to select for mutants that would secrete FlgM-Bla into the periplasmic space and show ampicillin resistance (Ap
r
). Ap
r
resulted from null mutations in the
flhE
gene, C-terminal truncation mutations in the
flhA
gene, null and dominant mutations in the
flk
gene, and
flgG
* mutations. All mutant classes required the hook length control protein (FliK) and the rod cap protein (FlgJ) for the secretion specificity switch to occur. However, neither the hook (FlgE) nor the hook cap (FlgD) protein was required for premature FlgM-Bla secretion in the
flgG
* and
flk
mutant strains, but it was in the
flhE
mutants. Unexpectedly, when deletions of either
flgE
or
flgD
were introduced into
flgG
* mutant strains, filaments were able to grow directly on the filamentous rod structures.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
43 articles.
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