title: Enterococcus faecalis utilizes maltose by connecting two incompatible metabolic routes via a novel maltose 6'-phosphate phosphatase (MapP).
abstract: Similar to Bacillus subtilis, Enterococcus faecalis transports and phosphorylates maltose via a phosphoenolpyruvate (PEP):maltose phosphotransferase system (PTS). The maltose-specific PTS permease is encoded by the malT gene. However, E. faecalis lacks a malA gene encoding a 6-phospho-α-glucosidase, which in B. subtilis hydrolyses maltose 6'-P into glucose and glucose 6-P. Instead, an operon encoding a maltose phosphorylase (MalP), a phosphoglucomutase and a mutarotase starts upstream from malT. MalP was suggested to split maltose 6-P into glucose 1-P and glucose 6-P. However, purified MalP phosphorolyses maltose but not maltose 6'-P. We discovered that the gene downstream from malT encodes a novel enzyme (MapP) that dephosphorylates maltose 6'-P formed by the PTS. The resulting intracellular maltose is cleaved by MalP into glucose and glucose 1-P. Slow uptake of maltose probably via a maltodextrin ABC transporter allows poor growth for the mapP but not the malP mutant. Synthesis of MapP in a B. subtilis mutant accumulating maltose 6'-P restored growth on maltose. MapP catalyses the dephosphorylation of intracellular maltose 6'-P, and the resulting maltose is converted by the B. subtilis maltose phosphorylase into glucose and glucose 1-P. MapP therefore connects PTS-mediated maltose uptake to maltose phosphorylase-catalysed metabolism. Dephosphorylation assays with a wide variety of phospho-substrates revealed that MapP preferably dephosphorylates disaccharides containing an O-α-glycosyl linkage.
authors.affiliation: INRA, Microbiologie de l'alimentation au service de la santé humaine (MICALIS), UMR1319, F-78350, Jouy en Josas, France.
authors.forename: Abdelhamid
authors.initials: A
authors.lastname: Mokhtari
authors.forename: Víctor S
authors.initials: VS
authors.lastname: Blancato
authors.forename: Guillermo D
authors.initials: GD
authors.lastname: Repizo
authors.forename: Céline
authors.initials: C
authors.lastname: Henry
authors.forename: Andreas
authors.initials: A
authors.lastname: Pikis
authors.forename: Alexa
authors.initials: A
authors.lastname: Bourand
authors.forename: María
authors.initials: M
authors.lastname: de Fátima Álvarez
authors.forename: Stefan
authors.initials: S
authors.lastname: Immel
authors.forename: Aicha
authors.initials: A
authors.lastname: Mechakra-Maza
authors.forename: Axel
authors.initials: A
authors.lastname: Hartke
authors.forename: John
authors.initials: J
authors.lastname: Thompson
authors.forename: Christian
authors.initials: C
authors.lastname: Magni
authors.forename: Josef
authors.initials: J
authors.lastname: Deutscher
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000378:metabolism; D013293:Enterococcus faecalis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D008320:Maltose / Q000378:metabolism*; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*; D000520:alpha-Glucosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D013403:Sugar Phosphates; C087475:maltose 6-phosphate; D008320:Maltose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C049150:maltose-6'-phosphate glucosidase; D000520:alpha-Glucosidases