Journal of Bacteriology, March 2000, p. 1739-1747, Vol. 182, No. 6
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Infection of Vibrio cholerae Requires the
tolQRA Gene Products
Graduate Program in Immunology1 and Division of Geographic Medicine/Infectious Disease,2 Tufts University School of Medicine, Boston, Massachusetts 02111
Received 4 October 1999/Accepted 21 December 1999
CTX
is a lysogenic filamentous bacteriophage that encodes
cholera toxin. Filamentous phages that infect Escherichia
coli require both a pilus and the products of tolQRA
in order to enter host cells. We have previously shown that
toxin-coregulated pilus (TCP), a type IV pilus that is an essential
Vibrio cholerae intestinal colonization factor, serves as a
receptor for CTX
. To test whether CTX
also depends upon
tol gene products to infect V. cholerae, we
identified and inactivated the V. cholerae tolQRAB
orthologues. The predicted amino acid sequences of V. cholerae TolQ, TolR, TolA, and TolB showed significant similarity
to the corresponding E. coli sequences. V. cholerae strains with insertion mutations in tolQ,
tolR, or tolA were reduced in their efficiency
of CTX
uptake by 4 orders of magnitude, whereas a strain with an
insertion mutation in tolB showed no reduction in CTX
entry. We could detect CTX
infection of TCP
V. cholerae, albeit at very low frequencies. However, strains with
mutations in both tcpA and either tolQ,
tolR, or tolA were completely resistant to
CTX
infection. Thus, CTX
, like the E. coli
filamentous phages, uses both a pilus and TolQRA to enter its host.
This suggests that the pathway for filamentous phage entry into cells
is conserved between host bacterial species.
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