Organization and characterization of three genes involved in d-xylose catabolism in Lactobacillus pentosus

Abstract

A cluster of three genes involved in D-xylose catabolism (viz. xylose genes) in Lactobacillus pentosus has been cloned in Escherichia coli and characterized by nucleotide sequence analysis. The deduced gene products show considerable sequence similarity to a repressor protein involved in the regulation of expression of xylose genes in Bacillus subtilis (58%), to E. coli and B. subtilis D-xylose isomerase (68% and 77%, respectively), and to E. coli D-xylulose kinase (58%). The cloned genes represent functional xylose genes since they are able to complement the inability of a L. casei strain to ferment D-xylose. NMR analysis confirmed that 13C-xylose was converted into 13C-acetate in L. casei cells transformed with L. pentosus xylose genes but not in untransformed L. casei cells. Comparison with the aligned amino acid sequences of D-xylose isomerases of different bacteria suggests that L. pentosus D-xylose isomerase belongs to the same similarity group as B. subtilis and E. coli D-xylose isomerase and not to a second similarity group comprising D-xylose isomerases of Streptomyces violaceoniger, Ampullariella sp. and Actinoplanes. The organization of the L. pentosus xylose genes, 5'-xylR (1167 bp, repressor) - xylA (1350 bp, D-xylose isomerase) - xylB (1506 bp, D-xylulose kinase) - 3' is similar to that in B. subtilis. In contrast to B. subtilis xylR, L. pentosus xylR is transcribed in the same direction as xylA and xylB.

Contribution of the phosphoenolpyruvate:mannose phosphotransferase system to carbon catabolite repression in Lactobacillus pentosus

“…The following L. pentosus strains were used : MD353 (wild-type ; Lokman et al, 1991), LPE4 (∆ccpA mutant, Ap R Em R ; Lokman et al, 1997), LPE6 (2DG R mutant ; Chaillou et al, 1999). The following plasmid was used : pMJ18 (containing the manB gene from L. curvatus ; Ap R Em R ; Veyrat et al, 1996).…”

Decreasing Accumulation of Acetate in a Rich Medium byEscherichia colion Introduction of Genes on a Multicopy Plasmid

“…The NagC protein, the regulator of the nag operon encoding proteins involved in the use of N-acetylglucosamine, 27) the ORF (the sequence published is incomplete and the function is unknown) downstream of the araJ gene 28 ) in E. coli, and the XylR protein, the regulator of the xyl operon encoding proteins involved in the use of xylose, in Bacillus subtilis 29 ) were found to have high homologies with the putative Mlc protein (Fig. 5).…”

Genetic Analysis of a Novel Pathway for d -Xylose Metabolism in Caulobacter crescentus

“…Two routes for D-xylose degradation in microorganisms have been described. Numerous bacteria, including Escherichia coli (15), Bacillus species (24,25), and Lactobacillus species (16), use xylose isomerase to convert D-xylose to xylulose, which is then phosphorylated to enter the pentose phosphate pathway. Although some fungi have recently been shown to use this "bacterial" pathway (11), fungi more commonly transform Dxylose into xylitol by using xylose reductase and xylitol dehydrogenase (13).…”