Characterization of the Salmonella typhimurium mgl operon and its gene products

Müller, Norbert; Heine, Hans-Georg; Boos, Winfried

doi:10.1128/jb.163.1.37-45.1985

Cited by 41 publications

(10 citation statements)

References 40 publications

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“…To verify galactose utilization by the mucus-associated bacteria we used the reporter plasmid pMGLB. This plasmid expresses GFP via the promoter of the mglBAEC operon which encodes a high-affinity ABC transporter for galactose uptake (Muller et al, 1985). We verified that gfp expression of pMGLB is induced in the presence of D-galactose in vitro (Fig.…”

Section: Effect Of Galactose-feeding and Expression Of The Mglbaec Opmentioning

confidence: 66%

Motility allows S. Typhimurium to benefit from the mucosal defence

et al. 2008

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SummaryThe mammalian intestine is colonized by a dense bacterial community, called microbiota. The microbiota shields from intestinal infection (colonization resistance). Recently, we have shown that enteropathogenic Salmonella spp. can exploit inflammation to compete with the intestinal microbiota. The mechanisms explaining the enhanced pathogen growth in the inflamed intestine are elusive. Here, we analysed the function of bacterial flagella in the inflamed intestine using a mouse model for acute Salmonella Typhimurium enterocolitis. Mutations affecting flagellar assembly (Fla -) and chemotaxis (Che -) impaired the pathogen's fitness in the inflamed intestine, but not in the normal gut. This was attributable to a localized source of high-energy nutrients (e.g. galactosecontaining glyco-conjugates, mucin) released as an element of the mucosal defence. Motility allows Salmonella Typhimurium to benefit from these nutrients and utilize them for enhanced growth. Thus, nutrient availability contributes to enhanced pathogen growth in the inflamed intestine. Strategies interfering with bacterial motility or nutrient availability might offer starting points for therapeutic approaches.

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Section: Effect Of Galactose-feeding and Expression Of The Mglbaec Opmentioning

confidence: 66%

Motility allows S. Typhimurium to benefit from the mucosal defence

et al. 2008

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“…Wild-type and di-cysteine mutant receptors were expressed by pSF5 overproduction in E. coli NM303 (F + mgl503 lacZ lacY + recA1), a mutant strain that makes no endogenous receptor (Muller et al, 1985). Cells were grown for 12 to 18 h at 37°C in tryptone broth (Miller, 1972) containing 25 μg ampicillin/ml and 1 mM-α-D-(+) fucose (Scholle et al, 1987).…”

Section: (B) Isolation Of Receptor Proteinmentioning

confidence: 99%

Thermal motions of surface α-helices in the d-galactose chemosensory receptor

Careaga

Falke

1992

Journal of Molecular Biology

230

314

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The D-galactose chemosensory receptor of Escherichia coli is a .32 kDa globular protein possessing two distinct structural domains, each organized in an alpha/beta folding motif. Helices I and X lie at adjacent approximately parallel positions on the surface of the N-terminal domain, near the hinge region. In order to analyze the relative thermal motions of these two helices, the present study utilizes a generalizable disulfide trapping approach: first, site-directed mutagenesis is used to place a pair of cysteine residues at locations of interest on the protein surface, then disulfide bond formation is used to trap intramolecular cysteine-cysteine collisions resulting from thermal motions. Specifically, four engineered di-cysteine receptors have been constructed, each possessing one cysteine at position 26 on helix I, and a second cysteine at varying positions on helix X. A fifth control receptor possesses one cysteine at position 26, and a second on the opposite surface of the molecule. These surface cysteine substitutions have little or no effect on the measurable receptor parameters as judged by ligand binding equilibria and kinetics, protein stability, and 19F nuclear magnetic resonance, indicating that the engineered receptors are useful probes of native backbone dynamics. Spatial and kinetic features of backbone motions have been investigated by measuring intramolecular disulfide formation rates for cysteine pairs in the fully liganded receptor. The resulting rates decrease monotonically with increasing distance between cysteines in the crystal structure, while no disulfide formation is observed for the control pair unless the molecule is unfolded. The minimum translational amplitudes of the observed backbone motions range from 4.5 to 15.2 A, and the minimum rotational amplitudes are as large as 35 degrees. For each motion the rate of intramolecular sulfhydryl-sulfhydryl collision has been estimated from the measured rate of disulfide formation: the 4.5 and 15.2 A translations yield approximately 10(4) and approximately 10 collisions s-1 molecule-1, respectively. These collision rates, which are faster than ligand dissociation, likely underestimate the actual motional frequencies since only an undetermined fraction of the total motions yield collisions. The simplest plausible trajectory capable of producing such collisions is a rate-limiting translation of one or both helices along their long axes, coupled with minor helix rotations. When sugar is removed from the receptor, a substantial increase in backbone dynamics is observed, indicating the presence of new long-range backbone trajectories. Overall, the results suggest that internal motions in proteins may have larger amplitudes than previously observed.

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“…Bacterial strains, phages, and plasmids. The strains used in this study are derivatives of E. coli K-12: JM109 [recAl endAl gyrA96 A(lac-proAB) (F' traD36 proAB lacIq lacZAM15)], JM105 [thi rpsL endA sbcBJS hspR4 A(lac-proAB) (F' traD36proAB lacIq lacZAM15)] (28), and NM303 (Fmgl-50 lacZ lacY+ recAl) (17). MC4100 [F-A(argF-lacUl69) araDl39 rpsLIS0 deoCI relAl ptsF25 flbB5301 rbsR] (6) was transformed with N3 (N', Strr Sulr Tetr) (1).…”

Section: Methodsmentioning

confidence: 99%

Interchangeability of the adsorption proteins of bacteriophages Ff and IKe

Endemann

Gailus

Rasched

1993

J Virol

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The wild-type adsorption protein (g3p) of filamentous phage IKe cannot be exchanged with its analogous protein in the related Ff (M13, fd, and fl) phage particles. Deletion mutants of the protein, however, are assembled into Ff phage particles. These hybrid Ff phage particles bearing deleted IKe g3p attach to N pili, thus conserving the host attachment property of the protein but not its infection-initiating function. This means that the attachment specificity is determined by IKe g3p independently of other phage components in contact with it. Infection initiation function, the process in which phage DNA is released into the host, in contrast seems to require either more complex structural features of the protein (for example, a certain oligomeric structure) provided only in the original particle, or a concerted action of g3p with another particle component, not replaceable by its homologous counterpart in the related phage.

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Characterization of the Salmonella typhimurium mgl operon and its gene products

Cited by 41 publications

References 40 publications

Motility allows S. Typhimurium to benefit from the mucosal defence

Motility allows S. Typhimurium to benefit from the mucosal defence

Thermal motions of surface α-helices in the d-galactose chemosensory receptor

Interchangeability of the adsorption proteins of bacteriophages Ff and IKe

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