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Identification of related genes in phages phi 80 and P22 whose products are inhibitory for phage growth in Escherichia coli IHF mutants.

ABSTRACT: Bacteriophage lambda grows in both IHF+ and IHF- host strains, but the lambdoid phage phi 80 and hybrid phage lambda (QSRrha+)80 fail to grow in IHF- host strains. We have identified a gene, rha, in the phi80 region of the lambda(QSRrha+)80 genome whose product, Rha, inhibits phage growth in an IHF- host. A search of the GenBank database identified a homolog of rha, ORF201, a previously identified gene in phage P22, which similarly inhibits phage growth in IHF- hosts. Both rha and ORF201 contain two possible translation start sites and two IHF binding site consensus sequences flanking the translation start sites. Mutations allowing lambda (QSRrha+)80 and P22 to grow in IHF- hosts map in rha and ORF201, respectively. We present evidence suggesting that, in an IHF+ host, lambda(QSRrha+)80 expresses Rha only late in infection but in an IHF- host the phage expresses Rha at low levels early in infection and at levels higher than those in an IHF+ host late in infection. We suspect that the deregulation of rha expression and, by analogy, ORF201 expression, is responsible for the failure of phi80, lambda(QSRrha+)80, and P22 to grow in IHF mutants.

SUBMITTER: Henthorn KS

PROVIDER: S-EPMC177009 | biostudies-other | 1995 Jun

REPOSITORIES: biostudies-other

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Identification of related genes in phages phi 80 and P22 whose products are inhibitory for phage growth in Escherichia coli IHF mutants.

Henthorn K S KS Friedman D I DI

Journal of bacteriology 19950601 11

Bacteriophage lambda grows in both IHF+ and IHF- host strains, but the lambdoid phage phi 80 and hybrid phage lambda (QSRrha+)80 fail to grow in IHF- host strains. We have identified a gene, rha, in the phi80 region of the lambda(QSRrha+)80 genome whose product, Rha, inhibits phage growth in an IHF- host. A search of the GenBank database identified a homolog of rha, ORF201, a previously identified gene in phage P22, which similarly inhibits phage growth in IHF- hosts. Both rha and ORF201 contain ...[more]

PMID: 7768817

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Project description:Enterotoxigenic Escherichia coli (ETEC) is a diverse and poorly characterized E. coli pathotype that causes diarrhea in humans and animals. Phages have been proposed for the veterinary biocontrol of ETEC, but effective solutions require understanding of porcine ETEC diversity that affects phage infection. Here, we sequenced and analyzed the genomes of the PHAGEBio ETEC collection, gathering 79 diverse ETEC strains isolated from European pigs with post-weaning diarrhea (PWD). We identified the virulence factors characterizing the pathotype and several antibiotic resistance genes on plasmids, while phage resistance genes and other virulence factors were mostly chromosome encoded. We experienced that ETEC strains were highly resistant to Enterobacteriaceae phage infection. It was only by enrichment of numerous diverse samples with different media and conditions, using the 41 ETEC strains of our collection as hosts, that we could isolate two lytic phages that could infect a large part of our diverse ETEC collection: vB_EcoP_ETEP21B and vB_EcoS_ETEP102. Based on genome and host range analyses, we discussed the infection strategies of the two phages and identified components of lipopolysaccharides ( LPS) as receptors for the two phages. Our detailed computational structural analysis highlights several loops and pockets in the tail fibers that may allow recognition and binding of ETEC strains, also in the presence of O-antigens. Despite the importance of receptor recognition, the diversity of the ETEC strains remains a significant challenge for isolating ETEC phages and developing sustainable phage-based products to address ETEC-induced PWD.IMPORTANCEEnterotoxigenic Escherichia coli (ETEC)-induced post-weaning diarrhea is a severe disease in piglets that leads to weight loss and potentially death, with high economic and animal welfare costs worldwide. Phage-based approaches have been proposed, but available data are insufficient to ensure efficacy. Genome analysis of an extensive collection of ETEC strains revealed that phage defense mechanisms were mostly chromosome encoded, suggesting a lower chance of spread and selection by phage exposure. The difficulty in isolating lytic phages and the molecular and structural analyses of two ETEC phages point toward a multifactorial resistance of ETEC to phage infection and the importance of extensive phage screenings specifically against clinically relevant strains. The PHAGEBio ETEC collection and these two phages are valuable tools for the scientific community to expand our knowledge on the most studied, but still enigmatic, bacterial species-E. coli.

Dataset Information

Identification of related genes in phages phi 80 and P22 whose products are inhibitory for phage growth in Escherichia coli IHF mutants.

Publications

Identification of related genes in phages phi 80 and P22 whose products are inhibitory for phage growth in Escherichia coli IHF mutants.

Similar Datasets

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