Bacteriophage OP1, lytic for Xanthomonas oryzae pv. oryzae, changes its host range by duplication and deletion of the small domain in the deduced tail fiber gene

Acinetobacter baumannii is an important Gram-negative opportunistic pathogen causing nosocomial infections. The emergence of multiple-drug-resistant A. baumannii isolates has increased in recent years. Directed toward phage therapy, a lytic phage of A. baumannii, designated Abp53, was isolated from a sputum sample in this study. Abp53 has an isometric head and a contractile tail with tail fibers (belonging to Myoviridae), a latent period of about 10 min, and a burst size of approximately 150 PFU per infected cell. Abp53 could completely lyse 27% of the A. baumannii isolates tested, which were all multiple drug resistant, but not other bacteria. Mg 2؉ enhanced the adsorption and productivity of, and host lysis by, Abp53. Twenty Abp53 virion proteins were visualized in SDS-polyacrylamide gel electrophoresis, with a 47-kDa protein being the predicted major capsid protein. Abp53 has a double-stranded DNA genome of 95 kb. Sequence analyses of a 10-kb region revealed 8 open reading frames. Five of the encoded proteins, including 3 tail components and 2 hypothetical proteins, were similar to proteins encoded by A. baumannii strain ACICU. ORF1176 (one of the tail components, 1,176 amino acids [aa]), which is also similar to tail protein gp21 of Klebsiella phage phiKO2, contained repeated domains similar to those within the ACICU_02717 protein of A. baumannii ACICU and gp21. These findings suggest a common ancestry and horizontal gene transfer during evolution. As phages can expand the host range by domain duplication in tail fiber proteins, repeated domains in ORF1176 might have a similar significance in Abp53.

Section: Resultsmentioning

confidence: 90%

Lytic Myophage Abp53 Encodes Several Proteins Similar to Those Encoded by Host Acinetobacter baumannii and Phage phiKO2

Lee

Tseng

Lin

et al. 2011

“…The EcoM-GJ1 RNAP has highest sequence similarity to the RNAPs of Xanthomonas oryzae phages OP1 and Xp10, which are members of the Siphoviridae (23,49). There is also significant homology with the RNAP of the T7-like virus Pseudomonas phage gh-1 ( Table 1).…”

Section: Discussionmentioning

confidence: 99%

Complete Genomic Sequence of Bacteriophage φEcoM-GJ1, a Novel Phage That Has Myovirus Morphology and a Podovirus-Like RNA Polymerase

Jamalludeen

Kropinski

Johnson

et al. 2008

The complete genome of EcoM-GJ1, a lytic phage that attacks porcine enterotoxigenic Escherichia coli of serotype O149:H10:F4, was sequenced and analyzed. The morphology of the phage and the identity of the structural proteins were also determined. The genome consisted of 52,975 bp with a G؉C content of 44% and was terminally redundant and circularly permuted. Seventy-five potential open reading frames (ORFs) were identified and annotated, but only 29 possessed homologs. The proteins of five ORFs showed homology with proteins of phages of the family Myoviridae, nine with proteins of phages of the family Podoviridae, and six with proteins of phages of the family Siphoviridae. ORF 1 encoded a T7-like single-subunit RNA polymerase and was preceded by a putative E. coli 70 -like promoter. Nine putative phage promoters were detected throughout the genome. The genome included a tRNA gene of 95 bp that had a putative 18-bp intron. The phage morphology was typical of phages of the family Myoviridae, with an icosahedral head, a neck, and a long contractile tail with tail fibers. The analysis shows that EcoM-GJ1 is unique, having the morphology of the Myoviridae, a gene for RNA polymerase, which is characteristic of phages of the T7 group of the Podoviridae, and several genes that encode proteins with homology to proteins of phages of the family Siphoviridae.Postweaning diarrhea (PWD) due to enterotoxigenic Escherichia coli (ETEC) is a major problem for the swine industry (2, 17, 36). The ETEC strains that cause this disease typically produce F4 (K88) or F18 fimbriae and belong to a small number of O serogroups, with O149 being dominant worldwide (2,17,19). Strains of this serogroup were responsible for recent exceptionally severe outbreaks of disease in pigs in Ontario (2,26,38). The outbreak strains were almost all O149:H10:F4, whereas O149 strains from earlier periods were all O149: H43:F4 (38). Since multidrug resistance is common among these ETEC strains (2,32,38), and the problem persists despite traditional approaches such as vaccination, antibiotic treatment, feed additives, and management strategies, it was decided to investigate the use of bacteriophages for prophylaxis and therapy.Phage therapy has been effective in the prevention and treatment of experimentally induced diarrhea due to ETEC in neonatal pigs (46) but has never been investigated for PWD. We therefore used a mixture of 10 strains of O149:H10 ETEC from PWD as host strains in order to isolate phages by standard procedures from pig sewage (9). Six phages (EcoM-GJ1 to EcoM-GJ6) were isolated and characterized on the bases of morphology and spectrum of activity against O149:H10:F4 and O149:H43:F4 ETEC strains, strains of other serotypes of ETEC, and the 72 strains of the ECOR collection. The phages were also compared with respect to DNA fragment patterns resulting from digestion with three restriction enzymes. The six phages were similar morphologically and in their restriction enzyme digestion patterns as well as in their ability to lyse all or almost ...

“…Furthermore, we detected a homolog of the OP1 tail fiber protein (Tfb, OP1-ORF25), which was thought to be involved in host range determination, mediated by variation in the combination of repetitive motifs at the N terminus (34).…”

Section: Figmentioning

confidence: 99%

Characterization of Bacteriophages Cp1 and Cp2, the Strain-Typing Agents for Xanthomonas axonopodis pv. citri

Ahmad

Ogawa

Kawasaki

et al. 2014

The strains of Xanthomonas axonopodis pv. citri, the causative agent of citrus canker, are historically classified based on bacteriophage (phage) sensitivity. Nearly all X. axonopodis pv. citri strains isolated from different regions in Japan are lysed by either phage Cp1 or Cp2; Cp1-sensitive (Cp1 s ) strains have been observed to be resistant to Cp2 (Cp2 r ) and vice versa. In this study, genomic and molecular characterization was performed for the typing agents Cp1 and Cp2. Morphologically, Cp1 belongs to the Siphoviridae. Genomic analysis revealed that its genome comprises 43,870-bp double-stranded DNA (dsDNA), with 10-bp 3=-extruding cohesive ends, and contains 48 open reading frames. The genomic organization was similar to that of Xanthomonas phage phiL7, but it lacked a group I intron in the DNA polymerase gene. Cp2 resembles morphologically Escherichia coli T7-like phages of Podoviridae. The 42,963-bp linear dsDNA genome of Cp2 contained terminal repeats. The Cp2 genomic sequence has 40 open reading frames, many of which did not show detectable homologs in the current databases. By proteomic analysis, a gene cluster encoding structural proteins corresponding to the class III module of T7-like phages was identified on the Cp2 genome. Therefore, Cp1 and Cp2 were found to belong to completely different virus groups. In addition, we found that Cp1 and Cp2 use different molecules on the host cell surface as phage receptors and that host selection of X. axonopodis pv. citri strains by Cp1 and Cp2 is not determined at the initial stage by binding to receptors.