Transport and Catabolism of Pentitols by Listeria monocytogenes

Transposon insertion intoListeria monocytogenes lmo2665, which encodes an EIIC of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS), was found to preventD-arabitol utilization. We confirm this result with a deletion mutant and show that Lmo2665 is also required forD-xylitol utilization. We therefore called this protein EIICAxl. Both pentitols are probably catabolized via the pentose phosphate pathway (PPP) becauselmo2665 belongs to an operon, which encodes the three PTSAxl components, two sugar-P dehydrogenases, and most PPP enzymes. The two dehydrogenases oxidize the pentitol-phosphates produced during PTS-catalyzed transport to the PPP intermediate xylulose-5-P.L. monocytogenes contains another PTS, which exhibits significant sequence identity to PTSAxl. Its genes are also part of an operon encoding PPP enzymes. Deletion of the EIIC-encoding gene(lmo0508) affected neitherD-arabitol norD-xylitol utilization, althoughD-arabitol induces the expression of this operon. Both operons are controlled by MtlR/LicR-type transcription activators (Lmo2668 and Lmo0501, respectively). Phosphorylation of Lmo0501 by the soluble PTSAxl components probably explains whyD-arabitol also induces the second pentitol operon. Listerial virulence genes are submitted to strong repression by PTS sugars, such as glucose. However,D-arabitol inhibited virulence gene expression only at high concentrations, probably owing to its less efficient utilization compared to glucose.J Mol Microbi...
Source: Journal of Molecular Microbiology and Biotechnology - Category: Microbiology Source Type: research