A LacI-family regulator activates maltodextrin metabolism of Enterococcus faecium

• Published in: PloS one 2013-08, Vol.8 (8), p.e72285-e72285
• Main Authors: Zhang, Xinglin, Rogers, Malbert, Bierschenk, Damien, Bonten, Marc J M, Willems, Rob J L, van Schaik, Willem
• Format: Article
• Language: English
• Subjects: Amylases; Antibiotics; Bacteria; Bacterial Proteins - genetics; Carbohydrates; Cloning; Clusters; Deletion mutant; Dextrins; Dextrose; Digestive system; Digestive tract; Drug resistance; E coli; Enterococcus faecalis; Enterococcus faecium; Enterococcus faecium - genetics; Enterococcus faecium - metabolism; Gastrointestinal tract; Gene deletion; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genetic transcription; Genomes; Genomics; Glucose; Gram-positive bacteria; Homology; Intestine; Lac Repressors - genetics; Maltodextrin; Maltose; Maltose - metabolism; Metabolism; Microorganisms; Multigene Family; Mutation; Oligonucleotide Array Sequence Analysis; Pathogens; Physiology; Plasmids; Polymerase chain reaction; Polysaccharides - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Starch; Starch - metabolism; Sugar; Sugars; Transcription; Transcriptome
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0072285

Enterococcus faecium is a gut commensal of humans and animals. In the intestinal tract, E. faecium will have access to a wide variety of carbohydrates, including maltodextrins and maltose, which are the sugars that result from the enzymatic digestion of starch by host-derived and microbial amylases. In this study, we identified the genetic determinants for maltodextrin utilization of E. faecium E1162. We generated a deletion mutant of the mdxABCD-pulA gene cluster that is homologous to maltodextrin uptake genes in other Gram-positive bacteria, and a deletion mutant of the mdxR gene, which is predicted to encode a LacI family regulator of mdxABCD-pulA. Both mutations impaired growth on maltodextrins but had no effect on the growth on maltose and glucose. Comparative transcriptome analysis showed that eight genes (including mdxABCD-pulA) were expressed at significantly lower levels in the isogenic ΔmdxR mutant strain compared to the parental strain when grown on maltose. Quantitative real-time RT-PCR confirmed the results of transcriptome analysis and showed that the transcription of a putative maltose utilization gene cluster is induced in a semi-defined medium supplemented with maltose but is not regulated by MdxR. Understanding the maltodextrin metabolism of E. faecium could yield novel insights into the underlying mechanisms that contribute to the gut commensal lifestyle of E. faecium.