Inactivation of <i>Francisella tularensis</i> Gene Encoding Putative ABC Transporter Has a Pleiotropic Effect upon Production of Various Glycoconjugates

<i>Francisella tularensis</i>, an intracellular pathogen causing the disease tularemia, utilizes surface glycoconjugates such as lipopolysaccharide, capsule, and capsule-like complex for its protection against inhospitable conditions of the environment. <i>Francisella</i> species also possess a functional glycosylation apparatus by which specific proteins are O-glycosidically modified. We here created a mutant with a nonfunctional <i>FTS_1402</i> gene encoding for a putative glycan flippase and studied the consequences of its disruption. The mutant strain expressed diminished glycosylation similarly to, but to a lesser extent than, that of the oligosaccharyltransferase-deficient <i>ΔpglA</i> mutant. In contrast to <i>ΔpglA</i>, inactivation of <i>FTS_1402</i> had a pleiotropic effect, leading to alteration in glycosylation and, importantly, to decrease in lipopolysaccharide, capsule, and/or capsule-like complex production, which were reflected by distinct phenotypes in host–pathogen associated properties and virulence potential of the two mutant strains. Disruption of <i>FTS_1402</i> resulted in enhanced sensitivity to complement-mediated lysis and reduced virulence in mice that was independent of diminished glycosylation. Importantly, the mutant strain induced a protective immune response against systemic challenge with homologous wild-type FSC200 strain. Targeted disruption of genes shared by multiple metabolic pathways may be considered a novel strategy for constructing effective live, attenuated vaccines

Inactivation of <i>Francisella tularensis</i> Gene Encoding Putative ABC Transporter Has a Pleiotropic Effect upon Production of Various Glycoconjugates

<i>Francisella tularensis</i>, an intracellular pathogen causing the disease tularemia, utilizes surface glycoconjugates such as lipopolysaccharide, capsule, and capsule-like complex for its protection against inhospitable conditions of the environment. <i>Francisella</i> species also possess a functional glycosylation apparatus by which specific proteins are O-glycosidically modified. We here created a mutant with a nonfunctional <i>FTS_1402</i> gene encoding for a putative glycan flippase and studied the consequences of its disruption. The mutant strain expressed diminished glycosylation similarly to, but to a lesser extent than, that of the oligosaccharyltransferase-deficient <i>ΔpglA</i> mutant. In contrast to <i>ΔpglA</i>, inactivation of <i>FTS_1402</i> had a pleiotropic effect, leading to alteration in glycosylation and, importantly, to decrease in lipopolysaccharide, capsule, and/or capsule-like complex production, which were reflected by distinct phenotypes in host–pathogen associated properties and virulence potential of the two mutant strains. Disruption of <i>FTS_1402</i> resulted in enhanced sensitivity to complement-mediated lysis and reduced virulence in mice that was independent of diminished glycosylation. Importantly, the mutant strain induced a protective immune response against systemic challenge with homologous wild-type FSC200 strain. Targeted disruption of genes shared by multiple metabolic pathways may be considered a novel strategy for constructing effective live, attenuated vaccines

Inactivation of <i>Francisella tularensis</i> Gene Encoding Putative ABC Transporter Has a Pleiotropic Effect upon Production of Various Glycoconjugates

<i>Francisella tularensis</i>, an intracellular pathogen causing the disease tularemia, utilizes surface glycoconjugates such as lipopolysaccharide, capsule, and capsule-like complex for its protection against inhospitable conditions of the environment. <i>Francisella</i> species also possess a functional glycosylation apparatus by which specific proteins are O-glycosidically modified. We here created a mutant with a nonfunctional <i>FTS_1402</i> gene encoding for a putative glycan flippase and studied the consequences of its disruption. The mutant strain expressed diminished glycosylation similarly to, but to a lesser extent than, that of the oligosaccharyltransferase-deficient <i>ΔpglA</i> mutant. In contrast to <i>ΔpglA</i>, inactivation of <i>FTS_1402</i> had a pleiotropic effect, leading to alteration in glycosylation and, importantly, to decrease in lipopolysaccharide, capsule, and/or capsule-like complex production, which were reflected by distinct phenotypes in host–pathogen associated properties and virulence potential of the two mutant strains. Disruption of <i>FTS_1402</i> resulted in enhanced sensitivity to complement-mediated lysis and reduced virulence in mice that was independent of diminished glycosylation. Importantly, the mutant strain induced a protective immune response against systemic challenge with homologous wild-type FSC200 strain. Targeted disruption of genes shared by multiple metabolic pathways may be considered a novel strategy for constructing effective live, attenuated vaccines