A bile-inducible membrane protein mediates bifidobacterial bile resistance.
Bottom Line: The high level of similarity to bile efflux pumps from other bifidobacteria suggests a significant and general role for Bbr_0838 in bile tolerance.Insertional inactivation of Bbr_0838 in B. breve UCC2003 resulted in a strain, UCC2003:838(800) , which exhibited reduced survival upon cholate exposure as compared with the parent strain, a phenotype that was reversed when a functional, plasmid-encoded Bbr_0838 gene was introduced into UCC2003:838(800) .This study represents the first in-depth analysis of a bile-inducible locus in bifidobacteria, identifying a key gene relevant for bifidobacterial bile tolerance.
Affiliation: Departamento de Microbiología y Bioquímica de Productos Lácteos, Instituto de Productos Lácteos de Asturias, Villaviciosa, Asturias, Spain.Show MeSH
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Mentions: Primer extension analysis on total RNA isolated from cells grown under sub‐inhibitory concentrations of cholate showed that the transcriptional start site (tss) is located at a Guanine residue 375 bp upstream of the start codon of the coding sequence. Sequences representing the putative −10 and −35 regions were located upstream from the tss (Fig. 6). Determination of this transcriptional start site is in accordance with the absence of gene expression in the gusA fusion containing only 162 bp upstream from the start codon (pNZ272‐short), as the transcriptional start site and −10 and −35 hexamers are not encompassed in this construct (Fig. 7).
Affiliation: Departamento de Microbiología y Bioquímica de Productos Lácteos, Instituto de Productos Lácteos de Asturias, Villaviciosa, Asturias, Spain.