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Journal of Bacteriology, November 2000, p. 5962-5968, Vol. 182, No. 21
Institute of Microbiology and Immunology,
National Yang Ming University, Pai-Tao, Taipei, 112, Taiwan
Received 16 February 2000/Accepted 5 August 2000
Phage AR1 is similar to phage T4 in several essential genes but
differs in host range. AR1 infects various isolates of
Escherichia coli O157:H7 but does not infect K-12 strains
that are commonly infected by T4. We report here the determinants that
confer this infection specificity. In T-even phages, gp37 and gp38 are
components of the tail fiber that are critical for phage-host
interaction. The counterparts in AR1 may be similarly important and,
therefore, were characterized. The AR1 gp37 has a sequence that differs
totally from those of T2 and T4, except for a short stretch at the N
terminus. The gp38 sequence, however, has some conservation between AR1 and T2 but not between AR1 and T4. The sequences that are most closely
related to the AR1 gp37 and gp38 are those of phage Ac3 in the T2
family. To identify the AR1-specific receptor, E. coli O157:H7 was mutated by Tn10 insertion and selected for an
AR1-resistant phenotype. A mutant so obtained has an insertion
occurring at ompC that encodes an outer membrane porin. To
confirm the role of OmpC in the AR1 infection, homologous replacement
was used to create an ompC disruption mutant (RM). When RM
was complemented with OmpC originated from an O157:H7 strain, but not
from K-12, its AR1 susceptibility was fully restored. Our results
suggest that the host specificity of AR1 is mediated at least in part through the OmpC molecule.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Characterization of the Distal Tail Fiber Locus and
Determination of the Receptor for Phage AR1, Which Specifically Infects
Escherichia coli O157:H7
*
Corresponding author. Mailing address: Institute of
Microbiology and Immunology, National Yang Ming University, Pai-Tao,
Taipei, 112, Taiwan. Phone: 886-2-2826-7112. Fax: 886-2-2821-2880. E-mail: wjsyu{at}ym.edu.tw.
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