title: Multiple sugar: phosphotransferase system permeases participate in catabolite modification of gene expression in Streptococcus mutans.
abstract: Streptococcus mutans is particularly well adapted for high-affinity, high-capacity catabolism of multiple carbohydrate sources. S. mutansenzyme II (EII(Lev)), a fructose/mannose permease encoded by the levDEFG genes, and fruA, which encodes a hydrolase that releases fructose from fructan polymers, are transcriptionally regulated by the LevQRST four-component signal transduction system. Here, we demonstrate that: (i) levDEFGX are co-transcribed and the levE/F intergenic region is required for optimal expression of levFGX; (ii) D-mannose is a potent inducer of the levD and fruA operons; (iii) CcpA regulates levD expression in a carbohydrate-specific manner; (iv) deletion of the genes for the fructose/mannose-EII enzymes of S. mutans (manL, fruI and levD) enhances levD expression; (v) repression of the LevQRST regulon by EII enzymes depends on the presence of their substrates and requires LevR, but not LevQST; and (vi) CcpA inhibits expression of the manL and fruI genes to indirectly control the LevQRST regulon. Further, the manL, ccpA, fruI/fruCD and levD gene products differentially exert control over the cellobiose and lactose operons. Collectively, the results reveal the existence of a global regulatory network in S. mutans that governs the utilization of non-preferred carbohydrates in response to the availability and source of multiple preferred carbohydrates.
authors.affiliation: Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Zeng
authors.forename: Robert A
authors.initials: RA
authors.lastname: Burne
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D053263:Gene Regulatory Networks; D005798:Genes, Bacterial; D008358:Mannose / Q000378:metabolism; D009876:Operon; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D012329:RNA, Bacterial / Q000235:genetics; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; C069286:catabolite control proteins, bacteria; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D008358:Mannose