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Transport of D-xylose in Lactobacillus pentosus, Lactobacillus casei, and Lactobacillus plantarum: Evidence for a mechanism of facilitated diffusion via the phosphoenolpyruvate:mannose phosphotransferase system

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Author: Chaillou, S. · Pouwels, P.H. · Postma, P.W.
Type:article
Date:1999
Institution: Centraal Instituut voor Voedingsonderzoek TNO
Source:Journal of Bacteriology, 16, 181, 4768-4773
Identifier: 235109
Keywords: Nutrition · Mannose · Phosphoenolpyruvate sugar phosphotransferase · Xylose · Bacterial growth · Carbohydrate transport · Diffusion · Enzyme mechanism · Fermentation · Lactobacillus · Lactobacillus casei · Lactobacillus pentosus · Lactobacillus plantarum · Nonhuman · Priority journal · Adenosine Triphosphate · Biological Transport, Active · Carbon Radioisotopes · Diffusion · Genetic Complementation Test · Kinetics · Lactobacillus casei · Mannose · Mutation · Phosphoenolpyruvate · Phosphoenolpyruvate Sugar Phosphotransferase System · Plasmids · Species Specificity · Transformation, Genetic · Xylose

Abstract

We have identified and characterized the D-xylose transport system of Lactobacillus pentosus. Uptake of D-xylose was not driven by the proton motive force generated by malolactic fermentation and required D-xylose metabolism. The kinetics of D-xylose transport were indicative of a low- affinity facilitated-diffusion system with an apparent K(m) of 8.5 mM and a V(max) of 23 nmol min-1 mg of dry weight-1. In two mutants of L. pentosus defective in the phosphoenolpyruvate:mannose phosphotransferase system, growth on D-xylose was absent due to the lack of D-xylose transport. However, transport of the pentose was not totally abolished in a third mutant, which could be complemented after expression of the L. curvatus manB gene encoding the cytoplasmic EIIB(Man) component of the EII(Man) complex. The EII(Man) complex is also involved in D-xylose transport in L. casei ATCC 393 and L. plantarum 80. These two species could transport and metabolize D-xylose after transformation with plasmids which expressed the D-xylose-catabolizing genes of L. pentosus, xylAB. L. casei and L. plantarum mutants resistant to 2- deoxy-D-glucose were defective in EII(Man) activity and were unable to transport D-xylose when transformed with plasmids containing the xylAB genes. Finally, transport of D-xylose was found to be the rate-limiting step in the growth of L. pentosus and of L. plantarum and L. casei ATCC 393 containing plasmids coding for the D-xylose-catabolic enzymes, since the doubling time of these bacteria on D-xylose was proportional to the level of EII(Man) activity.