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Biomedical subjects

M Lambrecht

Publications and source records attributed to M Lambrecht.

At least 19 recordsLinked to original sources
PubMed1999

Bi-functional gfp- and gusA-containing mini-Tn5 transposon derivatives for combined gene expression and bacterial localization studies.

The gfp gene, encoding the green fluorescent protein, was combined with the gusA gene, coding for the beta-glucuronidase enzyme, in mini-Tn5 transposon derivatives for use in Gram-negative bacteria. These mini-Tn5 elements allow simultaneously monitoring of gene expression and localization of the marked bacteria. Introduction of the resultant mini-Tn5 transposons into Rhizobium etli, Azospirillum brasilense and Pseudomonas stutzeri allowed us to visualise the interaction of these bacteria with their host plant. The dual-marker mini-Tn5 transposons constitute a powerful new tool for studying gene expression and ecology of bacteria in the environment and during the interaction with plants.

Azospirillum↗
PubMed1999

Characterization of a sugar-binding protein from Azospirillum brasilense mediating chemotaxis to and uptake of sugars.

Our approach to the isolation of plant-inducible bacterial genes of Azospirillum brasilense, based on the analysis of protein patterns of bacteria grown in the presence and in the absence of plant root exudates, led to the identification of an acidic 40 kDa protein. Cloning and sequencing analysis of the corresponding coding DNA region revealed the presence of two open reading frames transcribed in the same orientation. The deduced ORF1 protein, which corresponds to the 40 kDa protein, is very similar to the periplasmic ChvE protein, identified in Agrobacterium tumefaciens and involved in enhanced virulence. The deduced ORF2 protein shows homology to members of the LysR family of transcriptional regulators. The function of the ChvE-like protein in A. brasilense was investigated further. The protein, designated as SbpA (sugar binding protein A), is involved in the uptake of D-galactose and functions in the chemotaxis of A. brasilense towards several sugars, including D-galactose, L-arabinose and D-fucose. Expression of the sbpA gene requires the presence of the same sugars in the growth medium and is enhanced further in combination with carbon starvation of A. brasilense cells.

Agrobacterium tumefaciens↗
PubMed1999

Auxins upregulate expression of the indole-3-pyruvate decarboxylase gene in Azospirillum brasilense.

Transcription of the Azospirillum brasilense ipdC gene, encoding an indole-3-pyruvate decarboxylase involved in the biosynthesis of indole-3-acetic acid (IAA), is induced by IAA as determined by ipdC-gusA expression studies and Northern analysis. Besides IAA, exogenously added synthetic auxins such as 1-naphthaleneacetic acid, 2,4-dichlorophenoxypropionic acid, and p-chlorophenoxyacetic acid were also found to upregulate ipdC expression. No upregulation was observed with tryptophan, acetic acid, or propionic acid or with the IAA conjugates IAA ethyl ester and IAA-L-phenylalanine, indicating structural specificity is required for ipdC induction. This is the first report describing the induction of a bacterial gene by auxin.

Azospirillum brasilense↗